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.

Suicide after breast cancer: an international population-based study of 723,810 women.

Few studies have examined long-term suicide risk among breast cancer survivors, and there are no data for women in the United States. We quantified suicide risk through 2002 among 723,810 1-year breast cancer survivors diagnosed between January 1, 1953, and December 31, 2001, and reported to 16 population-based cancer registries in the United States and Scandinavia. Among breast cancer survivors, we calculated standardized mortality ratios (SMRs) and excess absolute risks (EARs) compared with the general population, and the probability of suicide. We used Poisson regression likelihood ratio tests to assess heterogeneity in SMRs; all statistical tests were two-sided, with a .05 cutoff for statistical significance. In total 836 breast cancer patients committed suicide (SMR = 1.37, 95% confidence interval [CI] = 1.28 to 1.47; EAR = 4.1 per 100,000 person-years). Although SMRs ranged from 1.25 to 1.53 among registries, with 245 deaths among the sample of US women (SMR = 1.49, 95% CI = 1.32 to 1.70), differences among registries were not statistically significant (P for heterogeneity = .19). Risk was elevated throughout follow-up, including for 25 or more years after diagnosis (SMR = 1.35, 95% CI = 0.82 to 2.12), and was highest among black women (SMR = 2.88, 95% CI = 1.44 to 5.17) (P for heterogeneity = .06). Risk increased with increasing stage of breast cancer (P for heterogeneity = .08) and remained elevated among women diagnosed between 1990 and 2001 (SMR = 1.36, 95% CI = 1.18 to 1.57). The cumulative probability of suicide was 0.20% 30 years after breast cancer diagnosis.