Second primary neoplasms in thyroid cancer patients

Second primary malignancies following thyroid cancer: a population-based study in Taiwan

OBJECTIVE

Most studies on second primary malignancies (SPMs) after primary thyroid cancer were conducted in USA or Europe. The discrepancy between SPMs in these studies could be attributed to geographical and ethnic heterogeneity. Thus, there is a clear need for another large-scale epidemiological study, particularly in Asian countries, to define the incidence and risk of SPMs in thyroid cancer survivors.

DESIGN

A population-based study was conducted using the nation-wide database from Taiwan Cancer Registry between 1979 and 2006.

METHODS

We quantified standardized incidence ratios (SIRs) and cumulative incidence of SPMs among 19,068 individuals (4205 males and 14,863 females) with primary thyroid cancer.

RESULTS

A total of 644 cases (3.38%) developed at least a SPM during 134,678 person-years of follow-up. The risk for subsequent SPMs was significantly greater than that of the general population (SIR=1.33, 95% CI 1.23-1.44). There was a greater risk of developing major salivary glands, nasopharyngeal, lung, thymus, breast (females), bladder, and brain cancers, and leukemia and lymphoma. We observed that the risk was highest within the first 5 years of diagnosis of thyroid cancer (SIR=5.29, 1.68, and 0.68 for ≤ 5, 5-10, and >10 respectively) and in the younger patients (SIR=1.81 vs 1.61 for <50 and ≥ 50 respectively). The median overall survival for primary thyroid cancer patients was 23.28 years, but it was only 4.73 years for those who developed SPMs.

CONCLUSION

Thyroid cancer is associated with a 33% risk increment of SPMs, which had a negative impact on survival. There are sites of SPMs in the Asian population that are distinctive from those in the Western population, suggesting that other genetic predisposition or environmental factors may play a role.

Incidence of second primary malignancies during a long-term surveillance of patients with differentiated thyroid carcinoma in relation to radioiodine treatment

PURPOSE

Controversies remain over the actual risk of developing a second primary malignancy (SPM) as a consequence of I-131 treatment in patients with differentiated thyroid carcinoma (DTC). The objective of this study was to evaluate the adjusted rate and risk estimate of SPM in radioiodine-treated patients after controlling for confounding factors.

MATERIALS AND METHODS

A retrospective cohort study was conducted on 973 cases randomly selected from a population of 9550 radioiodine-treated DTC patients. The cases with prior or coincident nonthyroid malignancies and those with SPM during the first 3 years of the initial I-131 treatment were not included. Age-standardized rate of SPM and its 95% confidence interval (CI) during a median of 6 (3-26) years follow-up in DTC patients was compared with that of the general population. A logistic multivariable analysis was also conducted to identify the potential covariate factors that might influence the risk of SPM.

RESULTS

Eleven patients from 7370 person-years at risk developed an SPM. The standardized rate ratio of nonthyroid malignancy was 0.81 (95% CI, 0.57-1.04) for the studied patients relative to the general population. The cumulative dose of I-131 more than 40 GBq (1.08 Ci) was the sole factor associated with increased odds of SPM, after adjusting for age, follow-up duration, histology of DTC, presence of metastasis, and history of external radiotherapy (odds ratio, 113; 95% CI, 8.6-1495.6; P < 0.0001).

CONCLUSIONS

The overall rate of SPMs was not significantly increased after a minimum interval of 3 years from the first I-131 treatment; however, the chance of this event may be radically increased in patients who had received a cumulative activity of I-131 exceeding 40 GBq (1.08 Ci).

Childhood thyroid cancers and radioactive iodine therapy: necessity of precautious radiation health risk management

One of the lessons from Chernobyl's legacy on health impact beyond 20 years is not only how to detect and treat the patients with radiation-associated thyroid cancers but how to follow up those who received radioactive iodine treatment repetitively after surgery in order to monitor any recurrence/worsening and also how to predict the risk of secondary primary cancers for their lifetime period. To evaluate the possibility of second primary tumors after radioactive iodine treatment, we reviewed the reports on risks from both external and internal radiation exposure, especially at high doses during childhood through an internet service of the National Library of Medicine and the National Institutes of Health, PubMed by the end of June, 2007, together with our own experience of Chernobyl childhood thyroid cancers. Children who were internally exposed after Chernobyl accident have a long-term risk of well differentiated thyroid cancers. Once they have disease, ironically radioactive iodine ablation is one of the useful therapies after surgical treatment. Elevated risks of solid cancers and leukemia have been found in radioiodine-treated patients, however, so far precious few reports from Chernobyl thyroid cancer patient were published. To reduce the adverse effects of radioactive iodine therapy on non-target tissues, recombinant human TSH has been applied and proved effective. Period of latency of second primary cancers may be very long. Therefore patients treated with high activities of radioactive iodine, especially children cases, should be carefully followed up during their whole lifespan.

Second primary malignancy risk in thyroid cancer survivors: a systematic review and meta-analysis

OBJECTIVE

To determine the risk of second primary malignancies (SPMs) in thyroid cancer survivors.

DESIGN

We performed a systematic review and meta-analysis examining the standardized incidence ratios (SIRs) of SPMs in thyroid cancer survivors (compared to individuals without thyroid cancer). Two independent reviewers screened citations and reviewed all full-text papers deemed potentially relevant. Final consensus was reached on inclusion of papers in the review. Data were pooled using fixed effects models.

MAIN OUTCOMES

Thirteen full-text papers were included. The incidence of SPMs in thyroid cancer survivors was increased with an SIR of 1.20 (95% confidence interval 1.17, 1.24) (based on pooled data from six studies of 70,844 thyroid cancer survivors). The SIR of the following SPMs was significantly increased: salivary gland, stomach, colon/colorectal, breast, prostate, kidney, brain/central nervous system, soft tissue sarcoma, non-Hodgkin's lymphoma, multiple myeloma, leukemia, bone/joints, and adrenal. A significantly reduced risk of lung and cervical cancers was observed.

CONCLUSIONS

Thyroid cancer survivors are at increased risk of SPMs, which may be related to disease-specific treatments or genetic predisposition.

Second primary cancers in thyroid cancer patients: a multinational record linkage study

CONTEXT

Increasing incidence and improved prognosis of thyroid cancer have led to concern about the development of second primary cancers, especially after radioiodine treatment. Thyroid cancer can also arise as a second primary neoplasm after other cancers.

OBJECTIVE

The objective of the study was to assess the risk of second primary cancer after thyroid cancer and vice versa.

DESIGN

This was a multinational record linkage study.

SETTING

The study was conducted at 13 population-based cancer registries in Europe, Canada, Australia, and Singapore.

PATIENTS OR OTHER PARTICIPANTS

A cohort of 39,002 people (356,035 person-yr of follow-up) with primary thyroid cancer were followed up for SPN for up to 25 yr, and 1,990 cases of thyroid cancer were diagnosed after another primary cancer.

MAIN OUTCOME MEASURES

To assess any possible excess of second primary neoplasms after thyroid cancer, the observed numbers of neoplasms were compared with expected numbers derived from age-, sex-, and calendar period-specific cancer incidence rates from each of the cancer registries, yielding standardized incidence ratios (SIRs). The SIR of second primary thyroid cancer after various types of cancer was also calculated.

RESULTS

During the observation period, there were 2821 second primary cancers (all sites combined) after initial diagnosis of thyroid cancer, SIR of 1.31 (95% confidence interval 1.26-1.36) with significantly elevated risks for many specific cancers. Significantly elevated risks of second primary thyroid cancer were also seen after many types of cancer.

CONCLUSION

Pooled data from 13 cancer registries show a 30% increased risk of second primary cancer after thyroid cancer and increased risks of thyroid cancer after various primary cancers. Although bias (detection, surveillance, misclassification) and chance may contribute to some of these observations, it seems likely that shared risk factors and treatment effects are implicated in many. When following up patients who have been treated for primary thyroid cancer, clinicians should maintain a high index of suspicion for second primary cancers.

Second primary malignancies in thyroid cancer patients

The late health effects associated with radioiodine ((131)I) given as treatment for thyroid cancer are difficult to assess since the number of thyroid cancer patients treated at each centre is limited. The risk of second primary malignancies (SPMs) was evaluated in a European cohort of thyroid cancer patients. A common database was obtained by pooling the 2-year survivors of the three major Swedish, Italian, and French cohorts of papillary and follicular thyroid cancer patients. A time-dependent analysis using external comparison was performed. The study concerned 6841 thyroid cancer patients, diagnosed during the period 1934-1995, at a mean age of 44 years. In all, 17% were treated with external radiotherapy and 62% received (131)I. In total, 576 patients were diagnosed with a SPM. Compared to the general population of each of the three countries, an overall significantly increased risk of SPM of 27% (95% CI: 15-40) was seen in the European cohort. An increased risk of both solid tumours and leukaemias was found with increasing cumulative activity of (131)I administered, with an excess absolute risk of 14.4 solid cancers and of 0.8 leukaemias per GBq of (131)I and 10(5) person-years of follow-up. A relationship was found between (131)I administration and occurrence of bone and soft tissue, colorectal, and salivary gland cancers. These results strongly highlight the necessity to delineate the indications of (131)I treatment in thyroid cancer patients in order to restrict its use to patients in whom clinical benefits are expected.

Epidemiological analysis of site relationships of synchronous and metachronous multiple primary cancers in the National Cancer Center, Japan, 1962-1996

BACKGROUND

Multiple primary cancer (MPC) has been recognized as a problem commonly encountered in routine medical practice. A study of MPC is necessary not only to provide insights into the etiology of cancer, but also to provide information for effective medical care by clinical oncologists.

METHODS

A cohort of 49,751 cancer patients who were admitted to the National Cancer Center Hospital between 1962 and 1996 was used to study the site relationship of MPC. Logistic and Poisson regression analyses using an internal reference group within the cohort were applied for the calculation of the prevalence odds ratio (POR) for site relationships of synchronous MPC and the incidence rate ratio (IRR) for those of metachronous MPC.

RESULTS

Three site combinations with elevated risks for both synchronous and metachronous MPCs, eight with elevated risk for synchronous MPC, five with elevated risk for metachronous MPC and six with decreased risk for synchronous MPC were identified with statistical significance. Among them, the increased risk of metachronous stomach cancer following lymphoma and myeoloma (POR = 1.0 and 1.1, P > 0.05; IRR = 2.5, P < 0.05) and the inverse site-correlation of synchronous MPC between [trachea, bronchus and lung] and other sites of the upper aerodigestive tract [lip, oral cavity and pharynx] (POR = 0.5 and 0.3, P < 0.05) and esophagus (POR = 0.7 and 0.3, P < 0.05) have not been reported previously.

CONCLUSIONS

Our results suggest that interventions for lymphoma and myeloma might affect the development of subsequent stomach cancer and additional etiological factors other than tobacco smoking are associated with the development of cancer in the upper aerodigestive tract.