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

• Published in: Breast cancer research : BCR 2021-02, Vol.23 (1), p.24-10, Article 24
• Main Authors: Ramin, Cody, Withrow, Diana R, Davis Lynn, Brittny C, Gierach, Gretchen L, Berrington de González, Amy
• Format: Article
• Language: English
• Subjects: Adult; Age; Aged; Aged, 80 and over; Breast cancer; Breast Neoplasms - epidemiology; Breast Neoplasms - etiology; Breast Neoplasms - history; Breast Neoplasms - pathology; Calendars; Cancer; Cancer surgery; Cancer therapies; Care and treatment; Chemotherapy; Confidence intervals; Contralateral breast cancer; Decision making; Development and progression; Diagnosis; Endocrine therapy; Epidemiology; Estrogen; Estrogen receptors; Female; Histology; History, 20th Century; History, 21st Century; Humans; Invasiveness; Mastectomy; Medical diagnosis; Middle Aged; Neoplasm Staging; Neoplasms, Second Primary - epidemiology; Neoplasms, Second Primary - etiology; Neoplasms, Second Primary - history; Patients; Population; Population Surveillance; Prognosis; Registries; Risk Assessment; Risk Factors; SEER; SEER Program; Trends; Tumors; United States - epidemiology; Women; Womens health
• ISSN: 1465-542X; 1465-5411; 1465-542X
• DOI: 10.1186/s13058-021-01400-3

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. 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). 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