Role of RAI in the management of incidental N1a disease in papillary thyroid cancer.

BACKGROUND: Following total thyroidectomy (TT) for papillary thyroid cancer (PTC), pathological assessment can occasionally reveal incidental perithyroidal lymph nodes (LNs) with occult metastases. These cN0pN1a patients often receive radioactive iodine (RAI) therapy for this indication alone. The aim of this study was to determine the central compartment nodal recurrence-free survival in patients treated without RAI compared to those who received RAI treatment. METHODS: An institutional database of 3664 previously untreated patients with differentiated thyroid cancer operated between 1986 and 2010 was reviewed. A total of 232 pT1-3 patients managed with TT and no neck dissection were subsequently found to have incidental level 6 LNs on pathology. Patients with other indications for RAI, such as extrathyroidal extension and close or positive margins, were excluded. One hundred and four patients remained for analysis. Kaplan-Meier method was used to determine central neck LN recurrence-free survival (RFS). RESULTS: The median age of the cohort was 40 years (range 17-83). The median follow-up was 53 months (range 1-211). The median number of positive LNs removed and maximum LN diameter were 1 (range 1-8) and 5 mm (range 1-16 mm), respectively. A total of 67 (64%) patients had adjuvant RAI and 37 (36%) did not. Patients with vascular invasion (P = 0·01), LNs >2 mm (P = 0·07) and >2 positive nodes (P = 0·06) were more likely to be selected for adjuvant RAI therapy. Patients without RAI therapy had similar 5-year central neck LN RFS compared to those treated with RAI: 96·2% vs 94·6%, respectively (P = 0·92). CONCLUSION: There is no difference in the 5-year central compartment nodal recurrence-free survival in patients treated without RAI compared to those who received RAI treatment.

Defining a Valid Age Cutoff in Staging of Well-Differentiated Thyroid Cancer.

BACKGROUND: Age 45 years is used as a cutoff in the staging of well-differentiated thyroid cancer (WDTC) as it represents the median age of most datasets. The aim of this study was to determine a statistically optimized age threshold using a large dataset of patients treated at a comprehensive cancer center. METHODS: Overall, 1807 patients with a median follow-up of 109 months were included in the study. Recursive partitioning was used to determine which American Joint Committee on Cancer (AJCC) variables were most predictive of disease-specific death, and whether a different cutoff for age would be found. From the resulting tree, a new age cutoff was picked and patients were restaged using this new cutoff. RESULTS: The 10-year disease-specific survival (DSS) by Union for International Cancer Control (AJCC/UICC) stage was 99.6, 100, 96, and 81 % for stages I-IV, respectively. Using recursive partitioning, the presence of distant metastasis was the most powerful predictor of DSS. For M0 patients, age was the next most powerful predictor, with a cutoff of 56 years. For M1 patients, a cutoff at 54 years was most predictive. Having reviewed the analysis, age 55 years was selected as a more robust age cutoff than 45 years. The 10-year DSS by new stage (using age 55 years as the cutoff) was 99.2, 98, 100, and 74 % for stages I-IV, respectively. CONCLUSION: A change in age cutoff in the AJCC/UICC staging for WDTC to 55 years would improve the accuracy of the system and appropriately prevent low-risk patients being overstaged and overtreated.

Microscopic Positive Margins in Differentiated Thyroid Cancer Is Not an Independent Predictor of Local Failure.

BACKGROUND: In contrast to other head and neck cancers, the impact of histological thyroid specimen margin status in differentiated thyroid cancer (DTC) is not well understood. The aim of this study was to investigate the prognostic value of margin status on local recurrence in DTC. METHOD: The records of 3664 consecutive patients treated surgically for DTC between 1986 and 2010 were identified from an institutional database. Patients with less than total thyroidectomy, unresectable or gross residual disease, or M1 disease at presentation and those with unknown pathological margin status were excluded from analysis. In total, 2616 patients were included in the study; 2348 patients (90%) had negative margins and 268 patients (10%) had positive margins. Microscopic positive margin status was defined as tumor present at the specimen's edge on pathological analysis. Patient, tumor, and treatment characteristics were compared by Pearson's chi-squared test. Local recurrence free survival (LRFS) was calculated for each group using the Kaplan Meier method. RESULTS: The median age of the cohort was 48 years (range 7-91 years) and the median follow-up was 50 months (range 1-330 months). Age, sex, and histology types were similar between groups. As expected, patients who had positive margins were more likely to have larger tumors (p<0.001), extrathyroidal extension (ETE) (p<0.001), multicentric disease (p<0.001), or nodal disease (p<0.001) and were more likely to receive adjuvant radioactive iodine therapy (p<0.001) as well as external beam radiotherapy (p<0.001). The LRFS at 5 years for patients with positive margins status was slightly poorer compared with patients with negative margins (98.9% vs. 99.5%, p=0.018). Twelve patients developed local recurrence-8/2348 (0.34%) patients with negative margins and 4/263 (1.52%) patients with positive margins. Univariate predictors of LRFS were sex (p=0.006), gross ETE (<0.001), and positive margins (p=0.018). However, when controlling for presence of gross ETE on multivariate analysis, microscopic positive margin status was not an independent predictor of LRFS (p=0.193). CONCLUSION: Patients with resectable, M0 disease that undergo total thyroidectomy have an excellent five year LRFS of 99.4%. Microscopic positive margin status was not a significant predictor for local failure after adjusting for ETE or pathological tumor (pT) stage.

The results of selective use of radioactive iodine on survival and on recurrence in the management of papillary thyroid cancer, based on Memorial Sloan-Kettering Cancer Center risk group stratification.

BACKGROUND: The American Thyroid Association guidelines recommend the routine use of radioactive iodine for remnant ablation (RRA) in all T3 or greater primary tumors, and selective use in patients with intrathyroidal disease >1 cm, or evidence of nodal metastases. The guidelines recognize that there is conflicting and inadequate data to make firm recommendations for most patients. The aim of this study was to analyze our institutional experience of the use of RRA in the management of papillary thyroid cancer, with a particular focus on outcomes for those patients selected not to receive RRA. METHODS: We retrospectively reviewed 1129 consecutive patients who underwent total thyroidectomy at the Memorial Sloan-Kettering Cancer Center between 1986 and 2005. Of these, 490 were pT1-2 N0, 193 pT1-2 N1, and 444 pT3-4. Details on recurrence and disease-specific survival were recorded by the Kaplan-Meier method and compared using the log-rank test. RESULTS: The five-year disease-specific survival and recurrence-free survival in the pT1/T2 N0, pT1-2 N1, and pT3-4 were 100% and 92%, 100% and 92%, and 98% and 87% respectively. Low-risk patients who were managed without RRA (who tended to have limited primary disease, pT1-2, and low-volume metastatic disease in the neck, pT1-2 N1-fewer than five nodes, all <1 cm greatest dimension) had five-year recurrence-free survival of >97%. In the group with advanced local tumors (pT3-4), those patients who did not receive RRA (who tended to have pT3 N0 disease) had five-year recurrence-free survival of >90%. CONCLUSION: Following appropriate surgical management, the majority of patients with low-risk local disease and even some patients with more advanced-stage (pT3) tumors or regional metastases have low rates of recurrence and high rates of survival when managed without RRA.

Poorly differentiated thyroid carcinoma presenting with gross extrathyroidal extension: 1986-2009 Memorial Sloan-Kettering Cancer Center experience.

PURPOSE: To describe the outcome of patients with poorly differentiated thyroid cancer (PDTC) presenting with gross extrathyroidal extension (ETE). MATERIALS AND METHODS: After obtaining Institutional Review Board approval, we performed a retrospective review of a consecutive series of thyroid cancer patients treated by primary surgical resection with or without adjuvant therapy at Memorial Sloan-Kettering Cancer Center from 1986 to 2009. Out of 91 PDTC patients, 27 (30%) had gross ETE (T4a), and they formed the basis of our study. Of 27 patients, 52% were women. The median age was 70 years (range 27-87 years). Ten patients (37%) presented with distant metastases; four to bone, three to lung, and three to both bone and lung. All patients had extended total thyroidectomy, except two who had subtotal thyroidectomy. Twenty patients (74%) had central compartment neck dissection and 11 also had lateral neck dissection. Four patients had pN0, six (30%) pN1a, and 10 (50%) pN1b neck disease. Twenty-one patients (77%) had adjuvant therapy: 15 (55%) radioactive iodine (RAI) only, three (11%) postoperative external beam radiation (EBRT) only, and three (11%) had both RAI and EBRT. Overall survival (OS), disease-specific survival (DSS), local recurrence-free survival (LRFS), and regional recurrence-free survival (RRFS) were calculated by the Kaplan Meier method. RESULTS: The median follow-up time was 57 months (range 1-197 months). The 5 year OS and DSS were 47% and 49%, respectively. This poor outcome was due to distant metastatic disease; 10 patients had distant metastases at presentation and a further six developed distant metastases during follow-up. Locoregional control was good with 5-year LRFS and RRFS of 70% and 62%, respectively. Overall, eight patients (30%) had recurrences: two had distant alone, two regional, two regional and distant, one local and distant, and one had local, regional, and distant recurrence. CONCLUSION: Aggressive surgery in patients with PDTC showing gross ETE resulted in satisfactory locoregional control. Due to the small proportion of patients who received EBRT (22%), it is not possible to analyze its benefit on locoregional control. Of significance is the observation that the majority of patients (60%) who presented with or subsequently developed distant metastases eventually died of distant disease. New systemic therapies to target distant metastatic disease are required for improvements in outcome.

Undetectable thyroglobulin after total thyroidectomy in patients with low- and intermediate-risk papillary thyroid cancer--is there a need for radioactive iodine therapy?

BACKGROUND: The efficacy of radioactive iodine therapy (RAI) in patients who have an undetectable thyroglobulin (Tg) level after total thyroidectomy in well-differentiated papillary thyroid cancer (PTC) is questionable. The objectives of this study were to report the risk of recurrence in patients with PTC who had an undetectable Tg level after total thyroidectomy managed with postoperative RAI and without RAI. METHODS: After approval by the institutional review board, 751 consecutive patients who had total thyroidectomy for PTC as well as postoperative Tg measurement were identified from our institutional database of 1163 patients treated for well-differentiated thyroid carcinoma at Memorial Sloan Kettering Cancer Center between 1999 and 2005. Of these, 424 patients had an undetectable postoperative Tg (defined as a Tg <1 ng/mL) of whom 80 were classified as low, 218 intermediate, and 126 high risk via use of the GAMES (grade, age, distant metastasis, extrathyroidal extension, and size of the neoplasm) criteria. Patient, neoplasm, and treatment characteristics were recorded on the low- and intermediate-risk patients. Recurrence was defined as any structural abnormality on examination or imaging and confirmed by fine-needle aspiration biopsy. Disease-specific survival and recurrence-free survival (RFS) were calculated with the Kaplan-Meier method. Univariate analysis was carried out by the log rank test and multivariate analysis by Cox proportional hazards method. RESULTS: In the low-risk group (n = 80), 35 patients received postoperative RAI and 45 did not. Comparison of patient and tumor characteristics showed patients treated without RAI were more likely to have T1 tumors (82% vs 60%, P = .027). There were no disease-specific deaths in either group. There was 1 neck recurrence in the group that did not receive RAI. Patients managed without RAI had a similar RFS to patients managed with RAI (96% vs 100%, P = .337). In the intermediate risk group (n = 218), 135 were managed with RAI and 83 without. Comparison of patient and tumor characteristics showed patients managed without RAI were more likely to be older patients (≥ 45 years: 90% vs 39%, P < .0005) with smaller tumors (pT1T2: 97% vs 62%, P < .0005) and negative neck disease (N0: 56% vs 30%, P < .0005). There were no disease specific deaths in either group. There were 7 recurrences, of which 6 were in the RAI cohort (5 regional, 1 distant) and 1 in the non-RAI cohort (1 regional). Patients managed without RAI had a similar RFS to patients managed with RAI (97% vs 96%, P = .234). CONCLUSION: Select low- and intermediate-risk group patients who have undetectable Tg after total thyroidectomy for PTC can be managed safely without adjuvant RAI with no increase in risk of recurrence.

The impact of microscopic extrathyroid extension on outcome in patients with clinical T1 and T2 well-differentiated thyroid cancer.

OBJECTIVE: To report the impact of microscopic extrathyroid extension (ETE) on outcome in patients with cT1/cT2 well-differentiated thyroid cancer (WDTC), and to determine the effect of extent of surgery and adjuvant radioactive iodine (RAI) treatment on outcome in patients with microscopic ETE. PATIENTS AND METHODS: From an institutional database, we identified 984 patients (54%) who underwent surgery for cT1/T2N0 disease. Of these, 869 patients were pT1/T2 and 115 were upstaged to pT3 based on the finding of microscopic ETE. Disease-specific survival (DSS) and recurrence-free survival (RFS) were analyzed for each group using the Kaplan-Meier method. In the pT3 group, factors predictive of outcome were analyzed by univariate and multivariate analyses. RESULTS: There was no difference in the 10-year DSS (99% vs 100%; P = .733) or RFS (98% vs 95%; P = .188) on comparison of the pT1/pT2 and pT3 cohorts. Extent of surgery and administration of postoperative RAI were not significant for recurrence on univariate or multivariate analysis in the pT3 cohort. CONCLUSION: Outcomes in patients with cT1T2N0 WDTC are excellent and not affected by microscopic ETE. The extent of resection and administration of postoperative RAI in patients with microscopic ETE does not impact survival or recurrence.

Disease-related death in patients who were considered free of macroscopic disease after initial treatment of well-differentiated thyroid carcinoma.

BACKGROUND: Death from well-differentiated thyroid cancer (WDTC) is rare, and over the past century there has been a trend away from local recurrence as the primary cause of death. The objective of our study was to report the cause of death from thyroid cancer in patients with WDTC treated with curative intent with surgery ± adjuvant radioactive iodine. METHODS: An institutional database of 1811 patients with WDTC treated surgically for WDTC between 1986 and 2005 was analyzed and identified 165 (9.4%) who had died. Case records were studied to determine the cause of death in each patient. RESULTS: Of the 165 deaths, 17 (10%) patients were confirmed to have died of thyroid cancer and 6 (4%) died of an unknown cause but had thyroid cancer present at the time of last follow-up. The remaining 142 (86%) died from other causes and were considered free of thyroid cancer at their last follow-up. We therefore identified only 23 cause-specific deaths from the entire cohort (1.3%). Of the 17 patients known to have died of thyroid cancer, all had distant recurrence. Ninety-four percent had pulmonary metastases. Of these, 47% also had bony metastasis at the time of death. Two patients had recurrent disease in the neck at the time of death, but both also had distant disease. Of the six patients (4%) who died of unknown causes but had thyroid cancer at last follow-up, four (67%) had distant disease alone, one (17%) had local and regional recurrence, and one had local and distant recurrence at last follow-up. CONCLUSION: After successful resection of WDTC, we report a low disease-specific death rate (1.3%). In contrast to earlier reports, death caused by central compartment disease in this recent series is very rare, with metastatic disease accounting for almost all fatalities.