Radiation and Second Primary Thyroid Cancer Following Index Head and Neck Cancer

Risk of second primary thyroid cancer in cancer survivors

A risk factor for thyroid cancer (TC) may be a history of former cancer and cancer therapy. The precise risk of a second primary thyroid carcinoma has not yet been revealed. In this study, we evaluated standardized incidence ratios (SIRs) of second primary thyroid cancer (SPTC) with consideration of different conditions and further analyzed the clinicopathological characteristics and survival of these patients. The cohort was selected from the US Surveillance, Epidemiology, and End Results (SEER) Program between 1975 and 2019. The standardized incidence ratios, morbidity risk, clinicopathological features, and survival of second primary thyroid carcinoma were analyzed. Propensity score matching (PSM) was used to balance covariates. Kaplan-Meier method was performed to assess the survival outcomes. Overall, 7066 patients with SPTC and 83,113 patients with primary TC were identified. The SIR of TC in tumor patients was 1.51/10,000, statistically higher than the natural population (0.94/10,000, P < 0.05). The most significant tumors contributing to the increased SIRs of SPTC were acute lymphocytic leukemia (3.49/10,000), Hodgkin's lymphoma-nodal (3.29/10,000), salivary gland cancer (3.23/10,000), and kidney and renal pelvis cancer (3.05/10,000). The incidence of TC increased significantly in tumor patients who received radiotherapy/chemotherapy before age 35. The age at diagnosis of the SPTC was much older than the primary TC (64.01 vs. 49.55 years, p < 0.001). The SPTC had a higher percentage of histological grades 3/4 (23.14% vs. 15.19%, p < 0.001). Survival analyses demonstrated a worse prognosis for the SPTC group compared to the primary TC group. But after PSM, the survival outcomes of the two groups tended to be equivalent (P = 0.584). The SIRs of TC are higher in tumor patients. The most significant factors contributing to the increased risk of SPTC were some specific former tumors and acceptance of radiotherapy/ chemotherapy before age 35. There was no significant difference in survival between SPTC and primary TC.

Polymorphisms of DNA Repair Genes in Thyroid Cancer

The incidence of thyroid cancer, one of the most common forms of endocrine cancer, is increasing rapidly worldwide in developed and developing countries. Various risk factors can increase susceptibility to thyroid cancer, but particular emphasis is put on the role of DNA repair genes, which have a significant impact on genome stability. Polymorphisms of these genes can increase the risk of developing thyroid cancer by affecting their function. In this article, we present a concise review on the most common polymorphisms of selected DNA repair genes that may influence the risk of thyroid cancer. We point out significant differences in the frequency of these polymorphisms between various populations and their potential relationship with susceptibility to the disease. A more complete understanding of these differences may lead to the development of effective prevention strategies and targeted therapies for thyroid cancer. Simultaneously, there is a need for further research on the role of polymorphisms of previously uninvestigated DNA repair genes in the context of thyroid cancer, which may contribute to filling the knowledge gaps on this subject.

Latency Trend Analysis as a Guide to Screening Malignancy Survivors for Second Primary Thyroid Cancer

Primary cancer survivors have a higher risk of developing second primary thyroid cancer (SPTC). Patients with SPTC who survived primary malignancies, diagnosed from 1975 to 2016, were identified from the Surveillance, Epidemiology, and End Results (SEER) database (SEER 18 Registry). A total of 33,551 cancer cases were enrolled in the final analysis. Individuals with a primary malignancy were at a significant 90% increased risk of developing SPTC (SIR = 1.90, 95%CI = 1.86−1.93, p < 0.05) compared to the general population. More than half (54.7%) of SPTC diagnoses were made in the first three years after primary cancer diagnosis, and the most aggressive presentations of SPTC occurred within the first year following malignancy. A latency trend analysis identified persistent high risk for development of SPTC after diagnosis of lymphoma, leukemia, soft tissue tumors, kidney, breast, and uterine cancer; elevated 10-year risk for most cancers such as salivary gland, melanoma, stomach, lung, colon, ovarian, pancreas, prostate, and bladder; and high 5-year risk after cancers such as larynx, oral, orbit, bone, small intestine, and liver. Our latency period model identifying risk according to each type of primary cancer may aid clinicians in identifying at-risk patients to be screened for thyroid cancer and guide them in developing a surveillance plan according to the latency period attributed to a patient’s primary cancer.

Deciphering the Risk of Developing Second Primary Thyroid Cancer Following a Primary Malignancy-Who Is at the Greatest Risk?

Simple Summary

Associations between thyroid cancer and breast cancer have been elucidated, in that patients with breast cancer have a greater risk of developing subsequent thyroid cancer. However, not much is known about the relationship other primary cancers and subsequent thyroid cancer. In this review, we completed a thorough review of the existing literature to understand the relationship between primary cancers and second primary thyroid cancer (SPTC). Our findings suggest that surveillance protocols should be considered for patients at a higher risk of SPTC, including those with primary breast, renal cell, basal cell, and ovarian cancers who are female and/or Caucasian.

Abstract

Background: It is critical to understand factors that may contribute to an increased risk of SPTC in order to develop surveillance protocols in high-risk individuals. This systematic review and meta-analysis will assess the association between primary malignancy and SPTC. Methods: A search of PubMed and Embase databases was completed in April 2020. Inclusion criteria included studies that reported the incidence or standardized incidence ratio of any primary malignancy and SPTC, published between 1980–2020. The PRISMA guidelines were followed and the Newcastle–Ottawa Scale was used to assess quality of studies. Results: 40 studies were included, which were comprised of 1,613,945 patients and 15 distinct types of primary cancers. In addition, 4196 (0.26%) patients developed SPTC following a mean duration of 8.07 ± 4.39 years. Greater risk of developing SPTC was found following primary breast (56.6%, 95%CI, 44.3–68.9, p < 0.001), renal cell (12.2%, 95%CI, 7.68–16.8, p < 0.001), basal cell (7.79%, 95%CI, 1.79–13.7, p = 0.011), and ovarian cancer (11.4%, 95%CI, 3.4–19.5, p = 0.005). SPTC patients were more likely to be females (RR = 1.58, 95%CI, 1.2–2.01, p < 0.001) and Caucasians (p < 0.001). Conclusions: Surveillance protocols should be considered for patients at a higher risk of SPTC, including those with primary breast, renal cell, basal cell and ovarian cancers who are female and/or Caucasian.

Analysis of overall survival in differentiated thyroid cancer patients with double primary malignancy

Differentiated thyroid cancer (DTC) survivors are at increased risk of developing double primary malignancy (DPM). The aim of this study was to investigate clinicopathological characteristics and survival in DTC patients diagnosed with DPM. A total of 975 patients with DTC diagnosed between 2013 and 2017, treated, and followed at a medical center in Taiwan were retrospectively reviewed. Data from enrolled patients were analyzed for differences in prognosis dependent on the presence of DPM, and which clinicopathological variables affected their prognosis. Among 975 thyroid cancer patients, 94 (9.6%) were diagnosed with DPMs and 16 (1.6%) patients died of any cause. DPM patients had a greater proportion of males, had a higher mean age, more commonly presented with a thyroid mass incidentally by imaging and cervical lymph node metastases, showed a more advanced thyroid cancer stage, and had a higher proportion of lymph node metastases. Overall survival (OS) was significantly lower in patients diagnosed with DPM. Male gender (hazard ratio [HR] = 4.597), two or more DPMs (HR = 8.071), and shorter time interval between two cancers occurrences (HR = 7.101) were significantly risk factors for DPM-related death. In conclusion, the risk of developing DPM in DTC patients was elevated in older, male patients with an advanced tumor-node-metastasis stage. DPM adversely affected the OS of thyroid cancer patients. Male gender, two or more DPMs, and shorter time interval between occurrences were significant risk factors for OS in DPM patients.

Occurrence of metachronous second primary cancer in head and neck cancer survivors: A systematic review and meta-analysis of the literature

OBJECTIVE

Head and neck cancer (HNC) is the sixth leading cancer worldwide with approximately 600,000 new cases per year. Several studies suggest that HNC survivors may have an increased risk of developing second primary cancers (SPCs). A systematic review and meta-analysis was performed aiming to quantify the overall and site-specific risk of metachronous SPCs in HNC survivors.

METHODS

PubMed, Web of Science and Scopus were searched to identify studies published until October 2019. Studies investigating the standardised incidence ratio (SIR) of metachronous SPC were included. A random-effects meta-analysis was performed to calculate the overall and site-specific SIRs. Newcastle-Ottawa Scale was used to assess the study's quality. Heterogeneity was quantified using the I² statistics and explored using meta-regression.

RESULTS

Twenty-six studies were included in the systematic review. Studies differed by the definition of metachronous SPC used. For the meta-analyses, the studies were grouped according to these definitions. In the three groups, the overall risk of metachronous SPC was increased. The highest SPC risk was for oropharynx, oesophagus and lung.

CONCLUSIONS

Head and neck cancer survivors are at increased overall risk of metachronous SPCs. The canonical upper aerodigestive sites, HNLE (head and neck, oesophagus and lung), were the SPC sites with the highest risk.

IMPLICATION FOR CANCER SURVIVORS

Our results emphasise the importance of targeted surveillance strategies aimed at early detection and tertiary preventive interventions.