The incidence of second primary tumors in thyroid cancer patients is increased, but not related to treatment of thyroid cancer

Abstract

Objective: The aim of the present study is to assess the prevalence of second primary tumors in patients treated for thyroid cancer. Furthermore, we wanted to assess the standardized risk rates for all second primary tumors, but especially for breast cancer, as data in the literature indicate an excessive risk in differentiated thyroid cancer (DTC) patients for this tumor. Materials and methods: We included consecutive patients, who received ablation treatment with I-131 at the Leiden University Medical Center between January 1985 and December 1999 (nZ282). The mean period of follow-up was 10.6G4.1 years. Results: Thirty-five of the 282 patients (12.4%) had a second primary tumor (SPT), either preceding or following the diagnosis of thyroid cancer. Five other patients had three primary tumors, including DTC. As a result, 40 additional tumors were found in this group, revealing an overall prevalence of 14.2%. Twenty tumors (7.1%) preceded the thyroid cancer with a mean interval of 5.7 years (range: 0.5-22.0 years), whereas 20 tumors (7.1%) occurred after this tumor with a mean interval of 6.7 years (range: 1.0-15.0 years). In 13 female patients, breast cancer was found as SPT. The standardized incidence rate (SIR) for all cancers after the diagnosis of DTC in this study population was not increased (1.13; confidence interval (CI): 0.68-1.69). However, we found an increased SIR of 2.26 (CI: 1.60-3.03) for all cancers either following or preceding DTC, which is mainly caused by a SIR of 3.95 (CI: 2.06-6.45) for breast cancer. Conclusion: Patients with DTC have an overall increased standardized incidence rate for second primary tumors, but not for second primary tumors following I-131 therapy. These findings suggest a common etiologic and/or genetic mechanism instead of a causal relation.European Journal of Endocrinology 155 801-806

The impact of the extent of thyroid resection complemented by radioiodine management on disease free status and discharge rates among Differentiated Thyroid Cancer patients: A retrospective analysis.

“…However our view point still stands based on the findings by other researchers whose results were based on larger samples. In the light of our findings and those of other researchers, 20,21 it is also worth taking into account the views of the British Thyroid Association with regards to management of DTC patients with radioiodine. They do not recommend use of radioiodine in cases where patients had carcinomas <1cm that do not show high risks features.…”

“…Verkooijen et al, 21 also reported elevated risks of development of breast secondary cancers post radioiodine therapy. However, the limited statistics in this study, that is 3/3 (100 per cent) of TL cases who apparently developed secondary cancers might be alarming.…”

Multiple Metachronous Malignancies, One Patient with Three Primary Malignancies

“…A relationship between the total dose of I 131 and SPT has been reported for solid cancers and leukemias [5]. Verkooijen et al differ to suggest that this phenomenon occurs only due to genetic predisposition and environmental factors, as at least half of breast cancers occur before the treatment with I 131 for thyroid cancer [6]. The co-occurrence may be related to a genetic deregulation, as the H23 gene, which is overexpressed in both thyroid and breast cancers.…”

DNA Repair Perspectives in Thyroid and Breast Cancer: The Role of DNA Repair Polymorphisms

“…One possible explanation for this is that the lesions produced by ionizing radiation are more likely to be repaired by BER, NHEJ and HR. Several authors have described the increased incidence of a second malignancy in patients after diagnosis of thyroid cancer (Brown et al, 2008;Canchola et al, 2006;Garner et al, 2007;Verkooijen et al, 2006), pointing out breast cancer as the most frequent occurrence. However, some authors also considered the opposite, thyroid cancer being subsequent to breast cancer, suggesting the exposure to radiotherapy as the main cause of second malignancy in adjacent organs as a result of scattered radiation (Adjadj et al, 2003;Huang et al, 2009).…”