COVID-19 and cancer risk arising from ionizing radiation exposure through CT scans: a cross-sectional study.

BACKGROUND: The surge in the utilization of CT scans for COVID-19 diagnosis and monitoring during the pandemic is undeniable. This increase has brought to the forefront concerns about the potential long-term health consequences, especially radiation-induced cancer risk. This study aimed to quantify the potential cancer risk associated with CT scans performed for COVID-19 detection. METHODS: In this cross-sectional study data from a total of 561 patients, who were referred to the radiology center at Imam Hossein Hospital in Shahroud, was collected. CT scan reports were categorized into three groups based on the radiologist's interpretation. The BEIR VII model was employed to estimate the risk of radiation-induced cancer. RESULTS: Among the 561 patients, 299 (53.3%) were males and the average age of the patients was 49.61 ± 18.73 years. Of the CT scans, 408 (72.7%) were reported as normal. The average age of patients with normal, abnormal, and potentially abnormal CT scans was 47.57 ± 19.06, 54.80 ± 16.70, and 58.14 ± 16.60 years, respectively (p-value < 0.001). The average effective dose was 1.89 ± 0.21 mSv, with 1.76 ± 0.11 mSv for males and 2.05 ± 0.29 mSv for females (p-value < 0.001). The average risk of lung cancer was 3.84 ± 1.19 and 9.73 ± 3.27 cases per 100,000 patients for males and females, respectively. The average LAR for all cancer types was 10.30 ± 6.03 cases per 100,000 patients. CONCLUSIONS: This study highlights the critical issue of increased CT scan usage for COVID-19 diagnosis and the potential long-term consequences, especially the risk of cancer incidence. Healthcare policies should be prepared to address this potential rise in cancer incidence and the utilization of CT scans should be restricted to cases where laboratory tests are not readily available or when clinical symptoms are severe.

Risk and Prognostics of Second Primary Cancer After Prostate Radiation Therapy.

INTRODUCTION: As overall survival in prostate cancer increases due to advances in early detection and management, there is a growing need to understand the long-term morbidity associated with treatment, including secondary tumors. The significance of developing radiation-associated secondary cancers in an elderly population remains unknown. METHODS: Patients diagnosed with prostate cancer between 1975 and 2016 in one of 9 Surveillance, Epidemiology, and End Results registries were included in this study. Risk of second primary pelvic malignancies (SPPMs) were assessed with death as a competing risk using the Fine-Gray model. Time-varying Cox proportional hazard models were employed to analyze risk to overall mortality based on secondary tumor status. RESULTS: A total of 569,167 primary prostate cancers were included in analysis with an average follow-up of 89 months. Among all prostate cancer patients, 4956 SPPMs were identified. After controlling for differences in age, year of diagnosis, and surgery at time of prostate cancer treatment, radiation receipt was associated with a significantly higher incidence of SPPMs (1.1% vs 1.8% at 25 years). Among those who received radiation during initial prostate cancer treatment (n = 195,415), developing an SPPM is significantly associated with worse survival (adjusted hazard ratio = 1.76), especially among younger patients (under age 63, adjusted hazard ratio = 2.36). CONCLUSIONS: While developing a secondary malignancy carries a detrimental effect on overall survival, the absolute risk of developing such tumors is exceedingly low regardless of radiation treatment.

Increased Screening Rates for Thyroid Cancer Among Residents Living Near Nuclear Power Plants.

Frequent screening for thyroid cancer has been suggested as a probable explanation for the observed high risk of thyroid cancer in nuclear power plant (NPP) areas. We aimed to compare thyroid cancer screening rates of residents living near NPPs to those of the general population. This study utilized data from two national survey-based studies in 2016 and in 2014, respectively, for residents (n = 1,200) living in administrative districts within 5 km of NPP sites as the interest group, and the general population (n = 228,712) including distant-living residents (n = 19,100) in administrative districts within 30 km of NPP sites as reference groups. We observed an increase in screening rates in residents near NPPs, which may lead to a higher possibility of thyroid cancer detection. Therefore, further epidemiological studies investigating radiation-induced thyroid cancer risk among residents near NPPs should be carefully designed and interpreted considering possible detection bias.

Is there a role for adjuvant therapy in radiation-induced angiosarcoma of the breast? A case report and review of the literature.

BACKGROUND: Angiosarcoma (AS) of the breast is very rare, accounting for 1% of all soft tissue breast tumors. AS may present as primary tumors of the breast or as secondary lesions usually associated with previous radiotherapy. Commonly, secondary AS affects older women (median age 67-71 years) with a clinical history of breast cancer. The preferred site of onset of RIAS is the edge of radiation fields, where radiation doses and tumor necrosis may be heterogeneous, resulting in a DNA damage and instability. Radical surgery is the treatment of choice, but no clear consensus exists on surgical management of breast AS. CASE REPORT: We describe an atypical case of relapsed RIAS after radical mastectomy, treated with new surgery and, considering the higher risk of recurrence, subsequent adjuvant chemotherapy with weekly paclitaxel. CONCLUSIONS: The frequency of radiation-induced angiosarcomas (RIAS) after breast-conserving surgery and radiotherapy has been increased to 0.14-0.5% among long survivors. Nevertheless, even if RIAS continues to be prognostically an extremely unfavorable cancer due to a high rate of recurrence, distant spread, and median overall survival (OS) of about 60 months, the benefits of loco-regional breast radiotherapy are clearly higher than the risk in developing angiosarcoma.

Contemporary diagnostic approach to atypical vascular lesion and angiosarcoma.

Vascular neoplasms account for a substantial fraction of cutaneous mesenchymal tumors, spanning from clinically indolent benign lesions to highly aggressive malignancies. These neoplasms present a distinctive challenge in terms of their diagnostic histopathology, both because of the breadth of their morphological manifestations and because of the significant histological overlap between different entities, even benign and malignant ones. The post-radiotherapy setting is particularly problematic diagnostically, insofar as radiation exposure predisposes not only to secondary angiosarcoma, but also to atypical vascular lesion, a largely benign proliferation of cutaneous blood vessels typically affecting the breast. To address these challenges, we explore the clinical, histological, and molecular features of malignant vascular neoplasia, including primary and secondary subtypes, through the comparative lens of atypical vascular lesion. In addition to highlighting the key morphological indicators of malignancy in superficial vasoformative tumors, we offer an approach that integrates clinical characteristics and molecular genetic profiling to facilitate accurate classification. With this current knowledge as our foundation, we also look ahead in an effort to frame some of the key unanswered questions regarding superficial vascular malignancies and their natural history, clinical management, and molecular underpinnings.

Secondary meningioma after cranial irradiation: case series and comprehensive literature review.

BACKGROUND: Secondary meningioma after cranial irradiation, so-called radiation-induced meningioma, is one of the important late effects after cranial radiation therapy. In this report, we analyzed our case series of secondary meningioma after cranial irradiation and conducted a critical review of literature to reveal the characteristics of secondary meningioma. MATERIALS AND METHODS: We performed a comprehensive literature review by using Pubmed, MEDLINE and Google scholar databases and investigated pathologically confirmed individual cases. In our institute, we found pathologically diagnosed seven cases with secondary meningioma between 2000 and 2018. Totally, 364 cases were analyzed based on gender, WHO grade, radiation dose, chemotherapy. The latency years from irradiation to development of secondary meningioma were analyzed with Kaplan-Meier analysis. Spearman's correlation test was used to determine the relationship between age at irradiation and the latency years. RESULTS: The mean age at secondary meningioma development was 35.6 ± 15.7 years and the mean latency periods were 22.6 ± 12.1 years. The latency periods from irradiation to the development of secondary meningioma are significantly shorter in higher WHO grade group (P = 0.0026, generalized Wilcoxon test), higher radiation dose group (P < 0.0001) and concomitant systemic chemotherapy group (P = 0.0003). Age at irradiation was negatively associated with the latency periods (r = -0.23231, P < 0.0001, Spearman's correlation test). CONCLUSION: Cranial irradiation at older ages, at higher doses and concomitant chemotherapy was associated with a shorter latency period to develop secondary meningiomas. However, even low-dose irradiation can cause secondary meningiomas after a long latency period. Long-term follow-up is necessary to minimize the morbidity and mortality caused by secondary meningioma after cranial irradiation.

Cranial Irradiation for Childhood Cancers and Adult Risk of Meningioma.

INTRODUCTION: Following cranial irradiation, there is an increased risk of developing secondary neoplasms, especially meningiomas. Despite childhood cancer survivors who have undergone cranial irradiation having an increased risk of acquiring radiation-induced meningioma (RIM), there is no widely used standard guideline for meningioma screening. METHODS: At a single institution, we reviewed three adult survivors of childhood cancer who were treated for RIM between 2010 and 2020. We recorded age at diagnosis for the primary lesion, the radiation dose, age at RIM diagnosis, and tumor characteristics including treatment, pathology, and outcome. Two had had T-cell acute lymphocytic leukemia and one a rhabdomyosarcoma. The age of diagnosis of the RIM ranged from 20 to 40 years, with latencies ranging from 18 to 33 years. All lesions were classified as WHO Grade I meningiomas, and only 1 patient had a subsequent recurrence. A literature search identified articles that address RIM: a total of 684 cases were identified in 36 publications. RESULTS: Mean radiation doses ranged from 1.4 gray to 70 gray. Mean age of diagnosis for secondary meningioma ranged from 8 to 53.4 years old, with latency periods ranging from 2.8 to 44 years. Given variability in the way that investigators have published their results, it is difficult to make a single recommendation for RIM screening. Using our experience and the literature, we devised two different screening protocols and calculated their expense. CONCLUSIONS: We recommend that data be standardized in a registry to provide greater insight into the clinical and resource allocation questions, especially as long-term survival of children with pediatric cancer into full adulthood becomes more commonplace worldwide.

Radiation Induced Atypical Vascular Lesion in the Breast.

BACKGROUND AND PURPOSE: Atypical vascular lesion (AVL) became a separate WHO diagnosis in November 2019. Due to a possible risk of developing angiosarcoma, extensive surgery with excision of AVL has been recommended but the benefit from this is questionable. We investigated whether the change in WHO classification has led to an increase in the number of patients diagnosed with AVL, thereby leading to an increase in extensive surgery. METHOD: The Danish National Pathology Databank was used to identify patients diagnosed with AVL between June 1, 2010 to June 31, 2020. The rate of AVL diagnosed before and after change in WHO classification was compared. RESULTS: In total, 13 cases of AVL were identified, 3 cases diagnosed before changes in WHO classification corresponding to 0.025 cases per month, compared to 8 cases, 1.143 cases per month, after the change in WHO classification. This corresponded to a 45-fold increase (95%CI: 10.88-265,31) (P < .0001) in AVL diagnosis. The mean patient age at diagnosis was 67 years. Patients received treatment varying from yearly follow up to extensive surgery. Non developed angiosarcoma in the follow-up period of 22 months. CONCLUSION: The changes in WHO classification of AVL has led to a considerable increase in the number of patients diagnosed with the lesion. No standardized treatment exists for this rare condition, but extensive surgery is often recommended to this frail population despite the lack of evidence for prognostic benefit from the procedure. Prospective follow-up studies are needed to determine the optimal treatment strategy.

Young people's perspectives of thyroid cancer screening and its harms after the nuclear accident in Fukushima Prefecture: a questionnaire survey indicating opt-out screening strategy of the thyroid examination as an ethical issue.

BACKGROUND: Overdiagnosis of thyroid cancer has become a major global medical issue. Ultrasound-based thyroid cancer screening has promoted overdiagnosis, and recently international recommendations state that it should not be conducted, even after a nuclear accident. The Fukushima thyroid cancer screening program was initiated in 2011 as a health policy after the nuclear accident. The risk of radiation-induced thyroid cancer was unlikely given the low radiation levels, but the thyroid cancer screening program has continued at 2-year intervals with a relatively high participation rate and is now in its fifth round. It is therefore crucial to clarify whether those targeted for screening understand the disadvantages of screening, and to identify factors that influenced their decision to participate. METHODS: We conducted an anonymous mail-based questionnaire among young people from Fukushima Prefecture (subjects) and a neighboring prefecture that was not targeted for screening (non-subjects). We asked them about the significance of the thyroid cancer screening in Fukushima Prefecture, their reasons for accepting or refusing screening, their perception of the harms of screening, and their opinions on thyroid examination at school. We compared the results of the questionnaire between subjects and non-subjects and between examinees (who were screened) and non-examinees (who declined screening). RESULTS: Only 16.5% of respondents were aware of the harms associated with thyroid cancer screening, with most perceiving that the benefits outweighed the harms. Comparison of subjects' and non-subjects' responses showed there were no significant differences between the two groups. Among subjects, there were also no differences in responses between examinees and non-examinees. The most common reason for participation in screening was that the screening was conducted in schools and perceived as obligatory. CONCLUSIONS: These results highlighted a serious ethical issue in that school-based screening leads to making young people think that it is mandatory screening in an opt-out and default setting manner, with a lack of knowledge about the disadvantages of screening. Based on the autonomy of the subjects and the ethical principle of the post-disaster, surveys after a nuclear disaster should be conducted in an opt-in style without an opt-out style such as school-based screening.

Risk of Second Primary Malignancies After External Beam Radiotherapy for Thyroid Cancer.

AIM: To investigate the association between external beam radiotherapy (EBRT) and the incidence of second primary tumors in patients with thyroid cancer. MATERIALS AND METHODS: Data were extracted from the Surveillance, Epidemiology, and End Results 9 database. The study cohort included patients diagnosed with thyroid cancer between 1973 and 2017. Risk factors for second primary malignancies were identified with Cox proportional hazards models. Propensity score-matched analyses were used to assess the association between EBRT and second primary malignancies. RESULTS: Out of 72,392 patients with thyroid cancer, 7,684 (10.6%) developed a subsequent primary malignancy. Propensity score-matched analysis demonstrated patients receiving EBRT were more likely to develop second primary malignancies [30-year cumulative incidence=35.3% (95% confidence interval (CI)=30.4-39.8% vs. 28.1% (95% CI=27.0-29.2%); hazard ratio=1.17 (95% CI=1.03-1.33)]. CONCLUSION: In patients with thyroid cancer, EBRT is associated with an increased incidence of second primary malignancies.

Estimating cancer risks due to whole lungs low dose radiotherapy with different techniques for treating COVID-19 pneumonia.

BACKGROUND: Low dose radiotherapy (LDRT) of whole lungs with photon beams is a novel method for treating COVID-19 pneumonia. This study aimed to estimate cancer risks induced by lung LDRT for different radiotherapy delivery techniques. METHOD: Four different radiotherapy techniques, including 3D-conformal with anterior and posterior fields (3D-CRT AP-PA), 3D-conformal with 8 coplanar fields (3D-CRT 8 fields), eight fields intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy using 2 full arcs (VMAT) were planned on the CT images of 32 COVID-19 patients with the prescribed dose of 1 Gy to the lungs. Organ average and maximum doses, and PTV dose distribution indexes were compared between different techniques. The radiation-induced cancer incidence and cancer-specific mortality, and cardiac heart disease risks were estimated for the assessed techniques. RESULTS: In IMRT and VMAT techniques, heart (mean and max), breast (mean, and max), and stomach (mean) doses and also maximum dose in the body were significantly lower than the 3D-CRT techniques. The calculated conformity indexes were similar in all the techniques. However, the homogeneity indexes were lower (i.e., better) in intensity-modulated techniques (P < 0.03) with no significant differences between IMRT and VMAT plans. Lung cancer incident risks for all the delivery techniques were similar (P > 0.4). Cancer incidence and mortality risks for organs located closer to lungs like breast and stomach were higher in 3D-CRT techniques than IMRT or VMAT techniques (excess solid tumor cancer incidence risks for a 30 years man: 1.94 ± 0.22% Vs. 1.68 ± 0.17%; and women: 6.66 ± 0.81% Vs. 4.60 ± 0.43%: cancer mortality risks for 30 years men: 1.63 ± 0.19% Vs. 1.45 ± 0.15%; and women: 3.63 ± 0.44% Vs. 2.94 ± 0.23%). CONCLUSION: All the radiotherapy techniques had low cancer risks. However, the overall estimated risks induced by IMRT and VMAT radiotherapy techniques were lower than the 3D-CRT techniques and can be used clinically in younger patients or patients having greater concerns about radiation induced cancers.

Non-Hodgkin lymphomas and ionizing radiation: case report and review of the literature.

Non-Hodgkin lymphoma (NHL) increased continuously since the last century in developed countries. While they are considered as disease in elder ages, a remarkable increasing incidence is also observed in German children and juveniles. The higher rates are interpreted by the changes in classification because diseases such as chronic lymphocytic leukaemia were also identified as NHL. Considerable rates of NHL were found in nuclear workers and liquidators of Chernobyl, i.e. in cases of low-dose chronical exposures. In Germany, we noticed three workers who developed NHL after decontamination of nuclear facilities. The bone marrow is generally considered as target organ for ionizing radiation, but NHL is obviously induced in the whole pool of lymphocytes. Therefore, the dosimetry in cases of typical occupational external and internal exposure must be revised. A high radiation sensitivity for NHL is a possible suspect and likely reason which may partly explain the continuous rise of the diseases in populations underlying the current increases of medical diagnostic exposure. NHL is also induced in children and juveniles with a history of diagnostic X-rays.

Impact of the model of long-term follow-up care on adherence to guideline-recommended surveillance among survivors of adolescent and young adult cancers.

PURPOSE: Adolescent and young adult cancer survivors require lifelong healthcare to address the late effects of therapy. We examined the impact of different provider models of long-term follow-up (LTFU) care on adherence to recommended surveillance. METHODS: We conducted a retrospective cohort study using administrative health databases in Ontario, Canada. Five-year survivors were identified from IMPACT, a database of patients aged 15-20.9 years at diagnosis of six cancers between 1992 and 2010. We defined three models of LTFU care hierarchically: specialized survivor clinics (SCCs), general cancer clinics (GCCs), and family physician (FP). We assessed adherence to the Children's Oncology Group surveillance guidelines for cardiomyopathy and breast cancer. Multistate models assessed adherence transitions and impacts of LTFU attendance. RESULTS: A total of 1574 survivors were followed for a mean of 9.2 years (range 4.3-13.9 years) from index (5-year survival). The highest level of LTFU attended in the first 2-years post-index was a GCC (47%); only 16.7% attended a SCC. By the end of study, 72% no longer attended any of the models of care and only 2% still attended an SCC. Among 188 survivors requiring breast cancer surveillance, 6.9% were adherent to their first required surveillance testing. Attendance at a SCC in the previous year and higher cumulative FP or GCC visits increased the rate of subsequently becoming adherent. Among 857 survivors requiring cardiomyopathy surveillance, 11% were adherent at study entry. Each subsequent SCC visit led to an 11.3% (95% CI: 1.05-1.18) increase in the rate of becoming adherent. CONCLUSION: LTFU attendance and surveillance adherence are sub-optimal. SCC follow-up is associated with greater adherence, but few survivors receive such care, and this proportion diminished over time. Interventions are needed to improve LTFU attendance and promote surveillance adherence.

Clinical characterization of radiation-associated muscle-invasive bladder cancer.

OBJECTIVE: To characterize the presentation, patterns of care, and outcomes of radiation-associated muscle-invasive bladder cancer (RA-MIBC) compared to primary (non-radiation associated) MIBC. RA-MIBC has been suggested to represent a more aggressive disease variant and be more difficult to treat compared to primary (non-radiation associated) MIBC. METHODS: We identified 60,090 patients diagnosed with MIBC between 1988-2015 using the Surveillance, Epidemiology, and End Results database and stratified patients based on whether radiation had been administered to a prior pelvic primary cancer. We used Fine-Gray competing risks regression to compare adjusted bladder cancer-specific mortality (BCSM) for RA-MIBC compared to primary MIBC. RESULTS: There were 1,093 patients with RA-MIBC and 58,997 patients with primary MIBC. RA-MIBCs were more likely to be T4 at diagnosis (21.0% vs 17.3%, P < .001), and less likely to be node-positive (10.3% vs 17.1%, P < .001). The rate of 5-year BCSM was significantly higher for patients with RA-MIBC vs primary MIBC (56.1% vs 35.3%, AHR 1.24, P < .001), even after stratification by other tumor, treatment and patient-specific factors. CONCLUSION: RA-MIBCs tended to present with higher grade and T stage disease and were less likely to receive curative treatment. Even when accounting for stage, grade, and receipt of treatment, patients with RA-MIBC had worse survival compared to those with primary MIBC. These findings suggest that RA-MIBC present unique clinical challenges and may also represent a biologically more aggressive disease compared to primary MIBC. Future research is needed to better understand the biology of RA-MIBC and develop improved treatment approaches.

Screening of chronic radiation proctitis and colorectal cancer using periodic total colonoscopy after external beam radiation therapy for prostate cancer.

OBJECTIVE: To investigate the incidence of colorectal cancer and chronic radiation proctitis after prostate radiotherapy using periodic total colonoscopy screening. METHODS: From February 2013 to January 2018, 270 patients who underwent external beam radiation therapy for prostate cancer were advised to receive periodic total colonoscopy screening annually. We evaluated the incidence and characteristics of colorectal cancer and chronic radiation proctitis. RESULTS: First, second, third, fourth and fifth total colonoscopy were performed in 256 (95%), 151 (56%), 60 (22%), 23 (8.5%) and 7 (2.6%) patients at a median of 14, 31, 42, 54 and 72 months after radiotherapy, respectively. The prevalence proportion of colorectal cancer in the first colonoscopy since radiotherapy was 3.9%. Twelve (4.4%) patients were diagnosed with colorectal cancer, including four invasive cancers, during a follow-up period. Eight of these 12 patients had not experienced rectal bleeding. The median time to diagnosis of colorectal cancer was 21 months. Chronic radiation proctitis was observed in 136 (50%) patients, including 67 (25%) patients with symptomatic bleeding. CONCLUSIONS: The high detection rate of asymptomatic radiation proctitis suggests the utility of total colonoscopy to screen for early-stage colorectal cancer prior to or following radiotherapy for prostate cancer. Considering the longevity after localized prostate cancer treatment, the awareness of chronic radiation-induced proctitis and the risk of colorectal cancer masked by bleeding is needed in treatment decision -making.

Residential radon and lung cancer characteristics at diagnosis.

PURPOSE: This study sought to ascertain whether there might be an association between radon concentrations and age, gender, histologic type, and tumor stage at diagnosis. MATERIALS AND METHODS: Lung cancer cases from different multicenter case-control studies were analyzed, and clinical data were retrieved from electronic health records and personal interviews. A radon device was placed in all dwellings of participants, and we then tested the existence of an association between residential radon and lung cancer characteristics at diagnosis. RESULTS: Of the total of 829 lung cancer cases included, 56.7% were smokers or ex-smokers. There was no association between indoor radon concentrations and age, gender, histologic type or tumor stage at diagnosis. Median indoor radon concentrations increased with age at diagnosis for men, but not for women. When analyzing participants exposed to more than 1000 Bq/m3, a predominance of small cell lung cancer and a higher presence of advanced stages (IIIB and IV) were observed. CONCLUSIONS: There seems to be no association between radon and age, gender, histologic type or tumor stage at diagnosis. Higher radon exposure is more frequent in the case of small-cell lung cancer.

Innumerable Meningiomas Arising in a Patient With Tuberous Sclerosis Complex Decades After Radiation Therapy.

Meningioma is the most common radiation-induced brain neoplasm, usually occurring after a latency of 20 - 35 years, with multiplicity in 10% of cases. Radiation-induced meningiomas (RIMs) have not previously been reported in patients with tuberous sclerosis complex (TSC), unlike their well-known occurrence in other familial tumor predisposition syndrome patients. We report a TSC patient who developed numerous intracranial meningiomas twenty five year after radiation therapy for subependymal giant cell astrocytoma (SEGA). Autopsy examination showed innumerable, coalescent, benign, meningothelial meningiomas, WHO grade 1, ranging in size from 0.2 cm to 3.3 cm. Autopsy also showed small residual SEGA, radiation-induced cerebral vasculopathy, and classic TSC features including several small subependymal nodules ("candle gutterings"), white matter radial heterotopia, facial angiofibromas, dental enamel pitting, one ash leaf spot, and multiple hepatic and renal angiomyolipomas. Next-generation sequencing analysis utilizing a 500+ gene cancer panel demonstrated chromosomal loss involving the majority of chromosome 22, including the NF2 gene locus, as well as a truncating nonsense mutation in TSC1 p. R509*. While TSC patients rarely require radiation therapy, this striking case suggests that patients with TSC should be monitored closely if cranial therapeutic radiation is administered.