Thyroid cancer incidence and trends by demographic and tumor characteristics in Oran, Algeria: 1993-2013, a population-based analysis.

OBJECTIVES: Incidence rates of thyroid cancer have dramatically increased over recent decades in many countries, particularly the papillary histotype and microcarcinomas. We examined thyroid cancer incidence and trends by demographic and tumor characteristics based on 1443 patients with thyroid cancer diagnosed between 1993 and 2013 in Oran district, in Northwest Algeria. METHODS: All thyroid cancer cases were abstracted from medical records and pathology reports and classified according to the International Classification for Diseases in Oncology, third edition. Age-specific, age-standardized incidence rates per 100 000 person-years, and annual percent changes (APC) in the incidence were calculated. RESULTS: Age-standardized incidence was 11.7 per 100 000 for women and 2.0 per 100 000 for men. Thyroid cancer incidence increased over time significantly in women (APC: +3.72%; P < 0.05), mostly due to an increased incidence of the papillary histotype (APC: +5.48%; P < 0.05), and microcarcinomas (APC: +17.34%; P < 0.05). During the same time period, the incidence of follicular thyroid carcinomas decreased (APC: -3.74%; P < 0.05). CONCLUSIONS: The results of our study showing an upward trend of thyroid cancer incidence driven largely by increases in the papillary histotype are consistent with previous studies. The higher increase has coincided with the introduction of fine needle aspiration and thyroid ultrasound in the 1990s, and may have led to overdiagnosis. However, the increased papillary-to-follicular ratio observed over time is possibly a late effect of iodine supplementation implemented in Algeria in 1967 to combat endemic goiter. Further larger-scale population-based research is needed to gain insight into thyroid cancer etiology.

Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: Epidemiology and Long-Term Outcomes in a Strictly Defined Cohort.

Background: A subset of encapsulated/circumscribed follicular variant of papillary thyroid carcinoma (FVPTC) was reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) in 2016 to reduce overtreatment of a low-risk tumor. Study objectives were to describe the epidemiology and long-term outcomes of NIFTP in a high-volume, urban, tertiary referral center. Methods: Among patients enrolled in the Boston Medical Center (BMC) Thyroid Cancer Registry, 110 cases of FVPTC underwent index thyroid surgery at BMC between 2000 and 2016. Historically, BMC pathologists assess all malignant nodules using sections ≤0.3 cm with evaluation of the entire nodule and capsule. After review of pathology reports to identify potential NIFTPs, slides were rereviewed using criteria established by the NIFTP Working Group in 2016 and 2018. We evaluated interobserver reliability using Cohen's Kappa coefficient. Results: Among 110 FVPTCs, 15 (13%) met NIFTP criteria; 11 women and 4 men, age range 31-64 (mean 47.5) years. Mean tumor diameter was 1.7 cm (compared with 2.2 cm for FVPTC). Among NIFTP cases, there were no lymph node metastases, distant metastases, or tumor recurrences. All NIFTP cases were American Thyroid Association (ATA) low risk compared with only 68% of FVPTC (p = 0.011). Among FVPTCs, 14% had positive lymph nodes at index operation. Four patients (4%) had distant metastases. Mean follow-up time was 46 and 69 months for FVPTC and NIFTP, respectively. Among FVPTCs with an excellent response to therapy (2015 ATA guidelines), there were no recurrences. Just over half (n = 8) of patients with NIFTP received postoperative radioactive iodine (RAI) therapy. Concordance between pathologists was high for ruling out NIFTP (75%), but only 36% for ruling in NIFTP. Overall, for NIFTP designation, Cohen's Kappa was 0.39, which is considered fair. Conclusions: Although this is a relatively small cohort, all NIFTP specimens underwent updated pathology review consistent with current guidelines; mean follow-up was nearly 6 years. NIFTP represents a small fraction of the total papillary neoplasia diagnosed at this tertiary referral center (2.3%). None of the NIFTP cohort experienced an adverse oncologic event, and there were no regional or distant metastases. Over 50% of patients with NIFTP received RAI. Thus, the NIFTP reclassification may substantially reduce the number of patients who require adjuvant therapies, such as completion surgery or RAI.

Randomised comparison of 1.1 GBq and 3.7 GBq radioiodine to ablate the thyroid in the treatment of low-risk thyroid cancer: a 13-year follow-up.

Purpose: The optimal activity of radioiodine (I-131) administered for ablation therapy in papillary and follicular thyroid cancer after thyroidectomy remains unknown in a long-term (> 10 year) follow-up. Some, shorter follow-up studies suggest that activities 1.1 GBq and 3.7 GBq are equally effective. We evaluated the long-term outcomes after radioiodine treatment to extend current knowledge about the optimal ablative dose of I-131.Methods: One hundred and sixty consecutive adult patients (129 females, 31 males; mean age 46 ± 14 y, range 18-89 y) diagnosed with histologically confirmed differentiated thyroid cancer, were randomised in a prospective, phase III, open-label, single-centre study, to receive either 1.1 GBq or 3.7 GBq of I-131 after thyroidectomy. At randomisation, patients were stratified according to the histologically verified cervical lymph node status and were prepared for ablation using thyroid hormone withdrawal. No uptake in the whole-body scan with I-131 and serum thyroglobulin concentration less than 1 ng/mL at 4-8 months after treatment was considered successful ablation.Results: Median follow-up time was 13.0 years (mean 11.0 ± 4.8 y; range 0.3-17.1 y). Altogether 81 patients received 1.1 GBq with successful ablation in 45 (56%) patients. In the original study, thirty-six patients (44%) needed one or more extra administrations to replete the ablation. Of these, 4 (8.9%) and 5 (14%) patients relapsed during the follow-up, respectively. Of the 79 patients treated with 3.7 GBq 45 (57%) had successful ablation after one administration of radioiodine and 34 (43%) needed several treatments. Of these, 2 (4.4%) and 9 (26.5%) patients relapsed, respectively. The groups did not differ in the proportion of patients relapsing (p = .591).Conclusion: During follow-up of median 13 years, 3.7 GBq is not superior to 1.1 GBq in the radioiodine treatment after thyroidectomy in papillary and follicular thyroid cancer.

Evaluation of the 2015 ATA Guidelines in Patients With Distant Metastatic Differentiated Thyroid Cancer.

CONTEXT: Current American Thyroid Association (ATA) Management Guidelines for the treatment of differentiated thyroid cancer (DTC) stratify patients to decide on additional radioiodine (RAI) therapy after surgery, and to predict recurring/persisting disease. However, studies evaluating the detection of distant metastases and how these guidelines perform in patients with distant metastases are scarce. OBJECTIVE: To evaluate the 2015 ATA Guidelines in DTC patients with respect to 1) the detection of distant metastases, and 2) the accuracy of its Risk Stratification System in patients with distant metastases. PATIENTS AND MAIN OUTCOME MEASURES: We retrospectively included 83 DTC patients who were diagnosed with distant metastases around the time of initial therapy, and a control population of 472 patients (312 low-risk, 160 intermediate-risk) who did not have a routine indication for RAI therapy. We used the control group to assess the percentage of distant metastases that would have been missed if no RAI therapy was given. RESULTS: Two hundred forty-six patients had no routine indication for RAI therapy of which 4 (1.6%) had distant metastases. Furthermore, among the 83 patients with distant metastases, 14 patients (17%) had excellent response, while 55 (67%) had structural disease after a median follow-up of 62 months. None of the 14 patients that achieved an excellent response had a recurrence. CONCLUSIONS: In patients without a routine indication for RAI therapy according to the 2015 ATA Guidelines, distant metastases would initially have been missed in 1.6% of the patients. Furthermore, in patients with distant metastases upon diagnosis, the 2015 ATA Guidelines are an excellent predictor of both persistent disease and recurrence.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features reclassification and its impact on thyroid malignancy rate and treatment.

BACKGROUND: The reclassification of noninvasive encapsulated follicular variant papillary thyroid carcinoma (FVPTC) to noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) may have significant implications by changing overall malignancy rates and minimizing the extent of surgical treatment. METHODS: A retrospective review of 847 patients who underwent thyroidectomy at a single institution from January 2010 to April 2016 was performed. The subgroup with FVPTC (n = 181) was re-reviewed by endocrine pathologists for reclassification to NIFTP. The overall rate of malignancy (ROM) and within each Bethesda classification was determined before and after the reclassification of NIFTP. The extent of thyroidectomy among others in patients reclassified as NIFTP was further reviewed. RESULTS: Of 847 patients who underwent thyroidectomy, there was an overall ROM of 58% (n = 495), the majority being papillary thyroid cancer (PTC) (n = 454, 92%). In 181 patients with FVPTC, 146 underwent pathology re-review. There were 32 cases (22%) reclassified as NIFTP, reducing the overall ROM to 55%. ROM decreased across Bethesda categories I to V by the following: 3% Bethesda I, 8% Bethesda II, 8% Bethesda III, 10% Bethesda IV, and 3% Bethesda V. Among NIFTP patients, 16 underwent total thyroidectomy and 16 underwent thyroid lobectomy, of which 12 had completion thyroidectomies (75%). Twenty patients (63%) underwent central neck dissection, and nine underwent postoperative radioactive iodine ablation treatment (28%). CONCLUSIONS: A significant proportion of patients with FVPTC reclassified as NIFTP may decrease the overall institutional thyroid ROM. On final pathology, NIFTP should be regarded as an indolent tumor requiring no further surgical treatment.

Iodine deficiency a persisting problem: assessment of iodine nutrition and evaluation of thyroid nodular pathology in Portugal.

BACKGROUND: The goal of eliminating iodine deficiency (ID) by the year 2000 has still not been achieved in several countries. More than 2 billion people worldwide (over 260 million school age children) remain ID. In Europe, there are still countries, such as Portugal, without national general population data on iodine nutrition (IN). This study aims at evaluating combined complementary data of the IN of the general population through urinary iodine concentration (UIC) and the thyroid histology profile from the inland region of Beira Interior (BI), in Portugal. METHODS: UIC from a population sample of 214 volunteers (131 females and 83 males), with ages ranging from 8 to 97 years (mean 51.5 years ± SD 20.74 years), from BI was determined; the thyroid histology pattern in BI (6-year period) was evaluated; and the iodine content of the largest surface water reservoir of BI, never previously reported, was measured. RESULTS: Median UIC of 62.6 µg/L was measured. Over 92 % of the population had UIC less than 100 µg/L. From 279 histology reports evaluated, the incidence of the different types of thyroid nodular pathology in BI was established. There were 60 histologic diagnoses of malignancy. The observed ratio of papillary to follicular carcinoma relatively close to 1 and the fairly high percentage of anaplastic carcinomas are characteristic of ID areas. CONCLUSIONS: The findings of this first general population study on IN from the inland region of BI, Portugal, document significant ID. This problem, with its serious public health implications, could be corrected by having affordable iodised salt widely and generally available and by promoting a proactive population attitude generated by ample public information and educational programs as to the negative consequences of ID.

Systematic Review of Trends in the Incidence Rates of Thyroid Cancer.

BACKGROUND: A large proportion of global increase in thyroid cancer (TC) incidence has been attributed to increased detection of papillary thyroid cancer (PTC). Nonetheless, some reports support a real increase in incidence. This study aimed to perform a systematic review to evaluate the changing trends in TC incidence and summarize potential risk factors predisposing to this trend. METHODS: Literature published in the English language between 1980 and August 2014 was searched via PubMed (MEDLINE) and OvidSP (EMBASE). Original studies on changes in TC incidence in defined geographic areas that described clear methods of case selection and population estimates were included. Data on incidence rates and risk factors were collected. RESULTS: Of 4719 manuscripts, 60 studies were included, of which 31 were from Europe, 13 from North America, and the rest from Asia (n = 9), Oceania (n = 4), and South America (n = 3). Fifty-three articles reported a significant increase in incidence (highest was a 10-fold increase in South Korea), six reported stable rates, and one noted a decrease. PTC was the commonest type reported to have increased in incidence (in 10 studies with relevant data). Follicular TC increased in incidence (in four studies), albeit at a lower rate compared with PTC. Data on risk factors were sparse; factors discussed included ionizing radiation, iodine deficiency, and supplementation. CONCLUSION: This systematic review strongly supports a widespread and persistent increase in TC incidence. Evidence for over-detection of PTC as the predominant influence includes increased numbers of smaller size tumors and improved or unchanged survival.

[Draft of the best medical treatment in patients with low-risk thyroid cancer]. / Návrh optimálního lécebného postupu v lécbe nízkorizikového karcinomu stítné zlázy.

INTRODUCTION: The incidence of well-differentiated low-risk thyroid cancer have increased globally over the last three decades. Thyroid cancer treatment relates to a suitable surgical procedure and the use of adjuvant radio-iodine therapy in selected patients. Evaluation of prognostic factors and risk stratification are critical for determining appropriate treatment. Survival of patients with low-risk thyroid cancer is excellent. Appropriate choice of medical treatment resulted in full recovery in most patients. Relapse risk increases with the size of the primary tumor, along with the findings of the risk factors in men. METHODS AND RESULTS: Our study included a total of 1 980 patients in whom were diagnosed T1a and T1b tumors between the years 2003 to 2012. The population included 1 675 women (84.6 %) of average age of 45.22 years and 305 men (15.4 %) of average age of 50.0 years. The bulk of the file represented papillary carcinomas (1 868; 94.4 %), and smaller group of follicular carcinomas (112; 5.6 %). Patients were divided into four groups according to tumor size. Patients were evaluated according to risk factors: unifocality no other risk factors, multifocality - more bearings in thyroid tumor, metastases in regional lymph nodes, distant metastases or combination of risk factors. Group A: In the monitored set of 678 patients with papillary and follicular microcarcinoma up to 5 mm, during histological input, the findings revealed one bearing (unifocal type of cancer) in 566 patients. Multifocality was found in 112 patients, local nodal metastasis were demonstrated in 24 cases and pulmonary metastasis was discove-red in 1 case. Group B: In this group there were 576 study patients with papillary and follicular microcarcinoma size of 5-10 mm. Histological findings were captured input one bearing carcinoma in 434 patients, 142 patients with multifocality, in 53 cases of local nodal metastasis, and 1 case of bone metastases. Group C: In this group there were 467 study patients with papillary and follicular microcarcinoma size 10-15 mm. The histological initial finding captured unifocal type of cancer in 344 patients, multifocality in 123 patients, in 45 cases local metastases and in 3 cases of pulmonary metastases. Group D: 259 patients were monitored in this group with breast size 16-20 mm. At the initial finding was captured one bearing cancer in 188 patients, multifocality in 71 patients, in 24 cases evidence of local metastases and 2 patients had a case of distant lung metastases. In patients in whom risk factors were found, radioiodine treatment was indicated. This included 744 patients. In this group of patients after a year or more, relapse was observed in 74 patients (9.94 %). In 1 236 patients who did not undergo radioiodine treatment, there was a relapse in 49 patients (3.96 %). CONCLUSION: Based on our analysis, it is necessary to stratify the risk of relapse according to risk factors. In case of missed radioiodine therapy in patients with low-risk cancer without confirmed risk factors, it is also necessary to have regular clinical, laboratory and ultrasound examination. It is important to distinguish patients with risk factors that may contribute to disease recurrence. Only in this way, on one hand we prevent excessive treatment of patients with low-risk thyroid cancer which leads to increased cost of health care, and on the other hand prevent reduced level of care for patients with an increase in relapses.

The risk of second primary malignancy is increased in differentiated thyroid cancer patients with a cumulative (131)I dose over 37 GBq.

BACKGROUND: The aim of this study was to investigate the risk factors for second primary malignancy (SPM) diagnosed after differentiated thyroid cancer (DTC). METHODS: A total of 2468 DTC patients who underwent thyroidectomy were reviewed. SPM was defined as a non-thyroidal malignancy, diagnosed at least 1 year after the diagnosis of thyroid cancer. Patients were divided into five groups according to cumulative (131)I dose: very high-activity (≥ 37.0 GBq), high-activity (22.3-36.9 GBq), intermediate-activity (5.56-22.2 GBq), low-activity (1.1-5.55 GBq) and no RAI. RESULTS: Among the 2468 patients, 61 (2.5%) had SPMs during 7.0 (1.0-33.0) years of median follow-up. Age above 40 years, male sex and very high-activity RAI were independent risk factors for the development of SPM. SPM-related mortality was highest in the very high-activity group, while DTC-related mortality was highest in the high-activity group. The overall mortality both from SPM and DTC was highest in the high-activity group. CONCLUSION: A cumulative (131)I dose <37.0 GBq did not increase the risk of SPM. A cumulative (131) I dose ≥ 37.0 GBq increased the risk of SPM and SPM-related mortality and decreased the DTC-specific mortality, resulting in a similar all-cause mortality compared with the low-activity RAI group. Using repeated high-dose RAI for treating RAI-responsive but persistent DTC patients needs careful consideration of the individual benefits from RAI vs the risk of developing SPM.

Therapeutic strategy for low-risk thyroid cancer in Kanaji Thyroid Hospital.

It is well-known that differentiated thyroid carcinoma (DTC) has a generally indolent character and shows a favorable prognosis in comparison with many other carcinomas. The therapeutic strategy for patients with DTC in Japan has differed from that in Western countries. Total thyroidectomy followed by radioactive iodine (RAI) ablation has been standard in Western countries, whereas limited hemi-thyroidectomy and subtotal thyroidectomy has been extensively accepted in Japan. Papillary thyroid carcinoma (PTC) accounts for over 90% of all thyroid cancers in Japan. The majority of patients with PTC are categorized into a low-risk group on the basis of the recent risk-group classification schemes, and they show excellent outcomes. Several management guidelines for thyroid cancers have been published in Western countries. However, the optimal therapeutic options for PTC remain controversial, and high-level clinical evidence aimed at resolving these issues is lacking. Moreover, as socioeconomic differences in medical care exist, conventional policies for the treatment of PTC have differed between Japan and other countries. This review focuses on the special features of treatment in Japan for patients with low-risk DTC involving subtotal thyroidectomy without adjuvant therapies, rather than total thyroidectomy with RAI, with the aim of preserving quality of life. At our institution in Japan, we have had extensive experience with RAI treatment for high-risk DTC patients, and this represents a very rare situation. Here we introduce the therapeutic strategy for low-risk thyroid cancer in Japan, including the measures adopted at our institution.

Malignancy rate in thyroid nodules classified as Bethesda category III (AUS/FLUS).

BACKGROUND: The Bethesda System for Reporting Thyroid Cytopathology is the standard for interpreting fine needle aspiration (FNA) specimens. The "atypia of undetermined significance/follicular lesion of undetermined significance" (AUS/FLUS) category, known as Bethesda Category III, has been ascribed a malignancy risk of 5-15%, but the probability of malignancy in AUS/FLUS specimens remains unclear. Our objective was to determine the risk of malignancy in thyroid FNAs categorized as AUS/FLUS at a comprehensive cancer center. METHODS: The management of 541 AUS/FLUS thyroid nodule patients treated at Memorial Sloan-Kettering Cancer Center between 2008 and 2011 was analyzed. Clinical and radiologic features were examined as predictors for surgery. Target AUS/FLUS nodules were correlated with surgical pathology. RESULTS: Of patients with an FNA initially categorized as AUS/FLUS, 64.7% (350/541) underwent immediate surgery, 17.7% (96/541) had repeat FNA, and 17.6% (95/541) were observed. Repeat FNA cytology was unsatisfactory in 5.2% (5/96), benign in 42.7% (41/96), AUS/FLUS in 38.5% (37/96), suspicious for follicular neoplasm in 5.2% (5/96), suspicious for malignancy in 4.2% (4/96), and malignant in 4.2% (4/96). Of nodules with two consecutive AUS/FLUS diagnoses that were resected, 26.3% (5/19) were malignant. Among all index AUS/FLUS nodules (triaged to surgery, repeat FNA, or observation), malignancy was confirmed on surgical pathology in 26.6% [CI 22.4-31.3]. Among AUS/FLUS nodules triaged to surgery, the malignancy rate was 37.8% [CI 33.1-42.8]. Incidental cancers were found in 22.3% of patients. On univariate logistic regression analysis, factors associated with triage to surgery were younger patient age (p<0.0001), increasing nodule size (p<0.0001), and nodule hypervascularity (p=0.032). CONCLUSIONS: In patients presenting to a comprehensive cancer center, malignancy rates in nodules with AUS/FLUS cytology are higher than previously estimated, with 26.6-37.8% of AUS/FLUS nodules harboring cancer. These data imply that Bethesda Category III nodules in some practice settings may have a higher risk of malignancy than traditionally believed, and that guidelines recommending repeat FNA or observation merit reconsideration.

Unusual malignant tumors of the thyroid gland.

BACKGROUND: Although situated on the last places among the statistical hierarchy of human malignancies, thyroid cancers (TC) are the most common tumors of the endocrine system. Follicular epithelium neoplasms account for more than 90% of these lesions with a favourable prognosis, while resting tumors (medullary, anaplastic, lymphoma, sarcoma etc) generally present a rapid unfavorable evolution with a low rate of survival. PATIENTS AND METHODS: In a series of 464 thyropathies personally treated, 72 cases of TC (15.5%) were identified. Fifty-seven patients presented epithelial TC a 34 papillary variant, 20 follicular variant and 8 mixed forms. Alongside these there were two medullary TC, 9 anaplastic TC and insular TC, and primary lymphoma and metastasis to the thyroid of a lung carcinoma each single case. Four cases have been described in patients who were aged 2-6 years at the time of the Chernobyl disaster. Out of the common types, based on our own taxonomic criteria, we selected a group of 36 TC with unusual clinical, histological and behavioural characteristics or particular pathological associations. RESULTS: Seven cases of occult TC, 7 cases with precessive adenopathy TC and 11 patients with TC associated with hyperthyroidism were registered. All of them underwent adapted thyroidectomies in which the presence of cancer was decisive for the extent of surgery. Medullary, insular and anaplastic TC were the most aggressive lesions and even extended surgery and complementary therapy failed to improve the prognosis of these patients. In the same category we included the cases presenting the coexistence of two TC types, pathologic dedifferentiation in recurrences and concurrent presence of another endocrine or nonendocrine cervical lesion. The a surgical dogma of total thyroidectomy cannot always be respected, so complementary therapeutic solutions must be applied. RESULTS were complex, registering steady recoveries in occult, hyperfunctioning and even in coexisting pathological lesions, but many recurrences and reinterventions with poor survival rates (a few weeks up to 2 years) in cases with reduced or absent histologic differentiation were also noted. Some lesions were inoperable. DISCUSSIONS AND CONCLUSIONS: Increasing clinician, surgeon and pathologist awareness of these distinct, but not rare anatomoclinical contingencies could contribute to their adequate diagnosis and treatment. Recent progress in knowledge of molecular carcinogenesis and promising successes of targeted chemotherapy trials with new drugs offer promising perspectives in the management of advanced or metastatic TC. Surgery still remains the cornerstone treatment for thyroid cancers.

Differentiated thyroid cancer in a Swedish county--long-term results and quality of life.

BACKGROUND: There is still no complete agreement about the proper treatment of differentiated thyroid cancer (DTC). MATERIAL AND METHODS: All patients (n=130) with DTC in a defined population, treated with surgery between 1985 and 1999, were carefully followed up (median 13.1 years). Fifty three were operated with subtotal and 77 with total thyroidectomy. Twenty seven percent of the patients in the subtotal group and 56% of those in the total thyroidectomy group had postoperative radioiodine ablation. Thirty nine patients had papillary cancers incidentally detected during surgery for benign disorders (median size 7 (1-30) mm). Living patients answered the Swedish version of the SF-36 health survey. RESULTS: Eleven of 106 patients considered tumour-free after primary surgery developed recurrences during follow-up. Fifteen patients (12%) died from DTC but only one within stage I-II (1.2%). No patient below 50 years of age at diagnosis died from DTC. Only three of 29 patients with isolated loco-regional spreading of their disease at the time of diagnosis have died from thyroid cancer. There was no statistically significant difference in the 10 year cancer-specific survival rate between those operated with subtotal or total thyroidectomy--irrespective of stage. Survival rate was significantly better for papillary than for follicular cancer. Mental and physical quality of life among patients treated for DTC were similar to the healthy Swedish population. CONCLUSIONS: Patients with DTC stage I-II (according to TNM) or low-risk (according to AMES) have an excellent prognosis. Treatment as well as follow-up should not be exaggerated.

Does Chernobyl accident have any effect on thyroid cancers in Turkey? A retrospective review of thyroid cancers from 1982 to 2006.

Besides the genetic and environmental factors, radiation is an important aetiological cause in the occurrence of thyroid cancer (TC), particularly papillary carcinoma. Chernobyl disaster led to a dramatic increase in the frequency of TC in Eastern Europe. We aimed to determine the data of TC in our unit from 1982 to 2006 and whether Chernobyl disaster has a possible effect on TC distribution. The data of 351 patients with TC are reviewed retrospectively. The dates at diagnosis were classified in five time periods. The ratios of TCs in our unit were concordant with the literature. Comparing the five 5-year periods, there was a significant decrease in the ratio of follicular carcinoma (p<0.01) although the ratio of other thyroid cancers did not change (p>0.05). The ratio of papillary microcarcinoma increased (p<0.01) while the ratio of classical form decreased (p<0.01). The differences between the time periods and the mean ages at diagnosis for each TCs were not significant (p>0.05). If Chernobyl disaster had any effect, the mean age at diagnosis would be younger. The decrease in the ratio of follicular carcinoma in our study may be due to iodine supplementation. The higher ratio of papillary microcarcinoma can be related to increased diagnostic scrutiny. Epidemiological studies are necessary to determine TC incidence in Turkey.

[Epidemiology of thyroid tumors: effect of environmental iodine intake].

The incidence of thyroid cancer has been reported to be 0.5-1.3%, when assessed by sonographic examination and 3.7-28.4% by histologic examination at autopsies. These incidences are much higher than those of clinically evident thyroid cancer, which are 2.0/100,000 for males and 7.2/100,000 for females, reported in Japan. In iodine deficient areas, chronic stimulation by TSH causes multinodular autonomous growth and function, leading to hyperthyroidism in middle-aged and elderly subjects. Incidence of Plummer's disease among Japanese with sufficient iodine intake is very low, accounting for 0.5-0.8% of all thyroid nodules and 0.3% of all thyrotoxic patients. The Plummer/Graves ratio was higher than 1 in endemic goiter area before iodine supplementation. Iodine intake affects the type of thyroid carcinoma. Decreased intake of iodine is associated with higher frequency of follicular and anaplastic cancers and lower frequency of papillary cancer. The high prevalence of papillary cancer(>85%) with good prognosis may explain the preferred selection of partial rather than total thyroidectomy in Japan.

Relevance of iodine intake as a reputed predisposing factor for thyroid cancer.

UNLABELLED: Iodine is a trace element that is essential for the synthesis of thyroid hormone. Both chronic iodine deficiency and iodine excess have been associated with hypertrophy and hyperplasia of follicular cells, attributed to excessive secretion of TSH. This may be associated to thyroid cancer risk, particularly in women. Experimental studies have documented thyroid cancer induction by elevation of endogenous TSH, although in a small number of animals. Iodine deficiency associated with carcinogenic agents and chemical mutagens will result in a higher incidence of thyroid malignancy. Inadequate low iodine intake will result in increased TSH stimulation, increased thyroid cell responsiveness to TSH, increased thyroid cell EGF-induced proliferation, decreased TGFbeta 1 production and increased angiogenesis, all phenomena related to promotion of tumor growth. Epidemiological studies associating iodine intake and thyroid cancer led to controversial and conflicting results. There is no doubt that introduction of universal iodine prophylaxis in population previously in chronic iodine-deficiency leads to a changing pattern of more prevalent papillary thyroid cancer and declining of follicular thyroid cancer. Also anaplastic thyroid cancer is practically not seen after years of iodine supplementation. Iodine excess has also been indicated as a possible nutritional factor in the prevalence of differentiated thyroid cancer in Iceland, Hawaii and, more recently, in China. IN CONCLUSION: available evidence from animal experiments, epidemiological studies and iodine prophylaxis has demonstrated a shift towards a rise in papillary carcinoma, but no clear relationship between overall thyroid cancer incidence and iodine intake.

Relevance of iodine intake as a reputed predisposing factor for thyroid cancer

Iodine is a trace element that is essential for the synthesis of thyroid hormone. Both chronic iodine deficiency and iodine excess have been associated with hypertrophy and hyperplasia of follicular cells, attributed to excessive secretion of TSH. This may be associated to thyroid cancer risk, particularly in women. Experimental studies have documented thyroid cancer induction by elevation of endogenous TSH, although in a small number of animals. Iodine deficiency associated with carcinogenic agents and chemical mutagens will result in a higher incidence of thyroid malignancy. Inadequate low iodine intake will result in increased TSH stimulation, increased thyroid cell responsiveness to TSH, increased thyroid cell EGF-induced proliferation, decreased TGFbeta 1 production and increased angiogenesis, all phenomena related to promotion of tumor growth. Epidemiological studies associating iodine intake and thyroid cancer led to controversial and conflicting results. There is no doubt that introduction of universal iodine prophylaxis in population previously in chronic iodine-deficiency leads to a changing pattern of more prevalent papillary thyroid cancer and declining of follicular thyroid cancer. Also anaplastic thyroid cancer is practically not seen after years of iodine supplementation. Iodine excess has also been indicated as a possible nutritional factor in the prevalence of differentiated thyroid cancer in Iceland, Hawaii and, more recently, in China. In conclusion: available evidence from animal experiments, epidemiological studies and iodine prophylaxis has demonstrated a shift towards a rise in papillary carcinoma, but no clear relationship between overall thyroid cancer incidence and iodine intake.

O iodo é essencial para a síntese de hormônios tireóideos e tanto a deficiência crônica deste halogeno como o excesso nutricional de iodo levam a hiperplasia e hipertrofia dos elementos foliculares (por excesso de TSH). Esse fenômeno pode se associar a maior risco de câncer de tireóide, especialmente no sexo feminino. Estudos experimentais documentam indução de câncer de tireóide após prolongado excesso circulante de TSH, o qual induz aumento da proliferação celular medida por fator de crescimento epidermal (EGF), decréscimo de síntese de fator de transformação do crescimento (TGFbeta 1) e aumento da angiogenese. Estudos epidemiológicos entre nutrição de iodo e câncer de tireóide são conflitantes. É, todavia, aceito que a correção de prévia deficiência de iodo com aporte nutricional adequado deste halogeno leva à maior prevalência de carcinoma papilífero (e decréscimo de carcinoma folicular). Em alguns países, o excesso de iodo foi apontado como causa aparente de maior prevalência de câncer de tireóide. Em conclusão: não existe uma relação causa-efeito entre iodo nutricional e prevalência de câncer de tireóide, e outros fatores intervenientes ambientais devem ser considerados.

Iodine intake and incidence of thyroid cancer in Denmark.

OBJECTIVE: Iodine intake is suspected to be a risk factor for thyroid cancer. Eastern Denmark is characterized by mild and western Denmark by moderate iodine deficiency, and this difference is associated with a 50% difference in the occurrence of goitre and thyrotoxicosis. The objective of the study was to determine whether the incidence of thyroid cancer differs between these two regions, as any difference would have important safety implications for the national iodine supplementation programme. DESIGN AND METHODS: We studied all thyroid cancers notified to the Danish Cancer Registry in the period 1973-1997, focusing on the four most frequent subtypes: papillary, follicular, anaplastic and medullary thyroid cancer. A Poisson regression model was used with models of goodness-of-fit for age, period, sex. RESULTS: No regional difference was found in the overall incidence of follicular (0.3% 100 000 person-years) or papillary (0.7% 100 000 person-years) thyroid cancer. A slight but nonsignificant increase in total incidence, resulting mainly from a significant increase in the incidence for the papillary subtype, was observed in both regions. CONCLUSION: The results suggest that modest differences in iodine intake do not affect thyroid cancer incidence or the distribution of subtypes.

Changing trends of incidence and prognosis of thyroid carcinoma in lower Franconia, Germany, from 1981-1995.

BACKGROUND: A population-based registry (PBR) in Lower Frankonia in southern Germany was conducted to evaluate the changes of incidence and prognosis of thyroid carcinoma (TC) in this area. METHODS: The study comprised 476 patients with differentiated thyroid carcinoma (DTC) from Lower Franconia (1.3 x 10(6) inhabitants) registered between 1981 and 1995 at the Regional Tumor Center. The incidence was assessed with respect to gender, age, histology, tumor stage, lymph node involvement and distant metastases in 5-year intervals (1981-1985, 1986-1990, and 1991-1995). RESULTS: An increasing rate of papillary thyroid carcinoma PTC and a decreasing rate of follicular thyroid carcinoma (FTC) were observed over the three time periods (1981-1985, 1986-1990, and 1991-1995). The overall incidence revealed no significant change with time for both females from 3.22 to 3.25 and 3.73 and males (1.07 to 1.54 and 1.69) between the three time periods. There was a significant improvement in outcome of patients with DTC with respect to life expectancy. CONCLUSIONS: Iodine prophylaxis does influence the distribution of the histologic types of thyroid cancer and leads to an increase in the ratio of papillary versus follicular carcinoma. Our study supports the hypothesis that the benefits of correcting iodine deficency outweigh the risks of iodine supplementation.

A prospective study of thyroid nodular disease in children and adolescents in western Poland from 1996 to 2000 and the incidence of thyroid carcinoma relative to iodine deficiency and the Chernobyl disaster.

BACKGROUND: In Poland, where soil is deficient in iodine, supplementation of iodine was introduced in 1935, discontinued in 1980, and then re-introduced in 1997. One of the effects of inadequate iodine intake, prior to 1997, was an increase in the prevalence of thyroid nodular disease (TND) in children. Chernobyl, located in the neighbouring country of Ukraine, suffered a catastrophic nuclear explosion in April 1986. PROCEDURE: A total of 411 children with TND (an incidence of 7.53/100,000) were diagnosed and registered in western Poland between 1996 and 2000 and further evaluated as a population-based study. RESULTS: Based on the patient's clinical status, ultrasound examination, scintiscan, laboratory tests, cytology and the family history, many of the patients qualified for surgery and, as a result, histopathologic data were obtained from 155 of the 411 patients operated on to date (37.7% of all TND). Thyroid carcinoma was detected in 37 of the operated children, i.e. 23.9% or 9.0% of all children with TND with a median incidence of 0.68/100,000. Papillary carcinoma was the predominant histologic type (26-70.3%) compared to follicular carcinoma (10-27.0%) and medullary carcinoma (1-2.7%). Retrospective analysis of the figures for the 23 years (1972-1995) showed that in that period a total of 23 thyroid carcinomas were registered. However, only 12 of these were detected in the 20-year period between 1972 and 1991, none in the years 1992-1993 and, significantly, 11 from 1994 to 1995. CONCLUSIONS: Thyroid carcinoma appears to be an ongoing and increasing problem in the children and adolescents of our region, and it is developing more intensively when compared, both to other parts of Poland and to previous statistics (2000 vs. 1985; P<0.002). Iodine deficiency and radiation resulting from the Chernobyl disaster might be important risk factors in the development of thyroid carcinoma in the young population analysed in our region in the period since 1994. The high percentage of follicular carcinoma and follicular adenoma with an undetermined prognosis (19 out of 46) indicates that the long-term iodine deficiency in our region may be more significant in the pathogenesis of malignant transformation than has previously been postulated.