Risk of contralateral breast cancer according to first breast cancer characteristics among women in the USA, 1992-2016.

BACKGROUND: Estimates of contralateral breast cancer (CBC) risk in the modern treatment era by year of diagnosis and characteristics of the first breast cancer are needed to assess the impact of recent advances in breast cancer treatment and inform clinical decision making. METHODS: We examined CBC risk among 419,818 women (age 30-84 years) who were diagnosed with a first unilateral invasive breast cancer and survived ≥ 1 year in the US Surveillance, Epidemiology, and End Results program cancer registries from 1992 to 2015 (follow-up through 2016). CBC was defined as a second invasive breast cancer in the contralateral breast ≥ 12 months after the first breast cancer. We estimated standardized incidence ratios (SIRs) of CBC by year of diagnosis, age at diagnosis, and tumor characteristics for the first breast cancer. Cumulative incidence of CBC was calculated for women diagnosed with a first breast cancer in the recent treatment era (2004-2015, follow-up through 2016). RESULTS: Over a median follow-up of 8 years (range 1-25 years), 12,986 breast cancer patients developed CBC. Overall, breast cancer patients had approximately twice the risk of developing cancer in the contralateral breast when compared to that expected in the general population (SIR = 2.21, 95% CI = 2.17-2.25). SIRs for CBC declined by year of first diagnosis, irrespective of age at diagnosis and estrogen receptor (ER) status (p-trends < 0.001), but the strongest decline was after an ER-positive tumor. The 5-year cumulative incidence of CBC ranged from 1.01% (95% CI = 0.90-1.14%) in younger women (age < 50 years) with a first ER-positive tumor to 1.89% (95% CI = 1.61-2.21%) in younger women with a first ER-negative tumor. CONCLUSION: Declines in CBC risk are consistent with continued advances in breast cancer treatment. The updated estimates of cumulative incidence inform breast cancer patients and clinicians on the risk of CBC and may help guide treatment decisions.

Secondary cancers after a lung carcinoid primary: a population-based analysis.

Carcinoid tumors of the lung were first described in 1937, yet little is known about their etiology. The aim of the present investigation was to determine if there was excess risk of secondary cancers in a population-based sample after a lung carcinoid tumor diagnosis which may provide insight to the etiology. Subjects were 1882 cases diagnosed with carcinoid tumors of the lung between 1988 and 2000 whose information was obtained from the Surveillance, Epidemiology and End Results (SEER) Program database. Standardized incidence ratios were calculated by dividing the observed number of second primary cancers by the expected number of cancers. Excess risk of breast cancer was seen following diagnosis of a carcinoid tumor (SIR=1.80 95% CI 1.22-2.55). When stratified by time after diagnosis, excess risk of breast cancers in women was seen in the first 5 years after carcinoid diagnosis (SIR=1.68 95% CI 1.08-2.50) but fewer than expected breast cancers were diagnosed greater than 5 years after carcinoid diagnosis (SIR=0.29 95% CI 0.09-0.68). Prostate cancers also occurred 2.8 times more often than expected (95% CI 1.66-4.43), with risk being elevated only in the first 5 years post-carcinoid diagnosis. Development of lung carcinoids may be the result of genetic predisposition or environmental exposures, particularly those that are hormonally related. The role of genetics and sex hormones in lung carcinoid development, as well as the identification of other risk factors, should be explored.