Young premenopausal women with breast cancer, especially estrogen receptor negative, are at significantly increased risk for subsequent ovarian cancer

Background: There is a modest risk of second cancers, among them ovarian cancer, after breast cancer. For BRCA1 and BRCA2 carriers, the risk increases substantially. We have analyzed the risk of ovarian cancer after breast cancer based on patient age and the estrogen receptor (ER) and progesterone receptor (PR) characteristics of the breast tumor. Methods: The study population was assembled using records from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute. The SEER program statistical analysis software package (SEER*Stat, version 8.2.1) was used to identify patients diagnosed with a primary breast cancer from 1990-2010. The SEER*Stat MP-SIR (Multiple Primary-Standardized Incidence Ratio) tool was used to calculate standardized incidence ratios (SIRs) and excess risk for ovarian cancer by comparing the patients' subsequent cancer profile to the number of cancers that would be expected based on incidence rates for the general U.S. population. Results: We used data from 316,801 cases of breast cancer. The overall number of ovarian cancer cases (n = 288) after ER negative PR negative breast cancer was significantly higher than expected (O/E =1.89, p < 0.05). In premenopausal women, that is, women younger than fifty, the ovarian cancer O/E was considerably higher than expected. Analysis of latency of ovarian cancer (months) after ER negative PR negative breast cancer revealed that in the youngest women the latency was shortest (p = 0.001, linear by linear association test for trend). Conclusion: Young women with pre-menopausal breast cancer, especially ER negative, are at significantly increased risk for subsequent ovarian cancer; the younger they are, the higher the risk. These women should be routinely tested for BRCA1 and BRCA2 mutations, and many might benefit from measures to prevent subsequent ovarian cancer.