van la Parra RFD, et al. - In the current study it was determined how often patients treated for breast cancer require breast biopsies during follow-up. For patients with breast cancer, data involving breast biopsies during follow-up and subsequent treatments from a large cohort of women with commercial insurance and Medicare were used in the context of therapy-planning discussions and survivorship expectations.

Methods

• Researchers performed a nationwide population-based cohort study.
• This study included 41,510 patients (64 years or younger) in a commercial insurance database and 80,369 patients (66 years or older) in the Surveillance, Epidemiology, and End Results (SEER)-Medicare database.
• From January 1, 2000, through December 31, 2011, patients were diagnosed with incident invasive breast cancer (stages I-III).
• To identify biopsy rates during follow-up, they used diagnosis and procedural codes.
• Data analysis was performed from March 3 through October 3, 2017.
• They calculated cumulative incidence and adjusted risk of breast biopsy and subsequent breast cancer treatment using the Kaplan-Meier method and Cox proportional hazards regression.
• In this study, all statistical tests were 2 sided.

Results

• Five- and 10-year overall incidences of breast biopsy in the commercial insurance cohort were 14.7% and 23.4%, respectively, and in the SEER-Medicare cohort were 11.8% and 14.9%, respectively, among the 121,879 patients in the study population.
• Women treated with brachytherapy showed higher 5-year estimated incidence of breast biopsy (24.0% in the commercial insurance and 25.0% in the SEER-Medicare cohorts) than those treated with whole-breast irradiation (16.7% in the commercial insurance and 15.1% in the SEER-Medicare cohorts); this incidence rate persisted after multivariate adjustment in the commercial insurance (hazard ratio [HR], 1.53; 95% CI, 1.38-1.70; P < .001) and SEER-Medicare (HR, 1.76; 95% CI, 1.63-1.91; P < .001) cohorts.
• Biopsy was observed to have independent association with adjuvant chemotherapy use (HR, 1.31; 95% CI, 1.25-1.37; P < .001) and patient age (>85 vs 66-69 years; HR, 0.40; 95% CI, 0.36-0.44; P < .001) in the SEER-Medicare cohort and endocrine therapy in the commercial insurance (HR, 0.88; 95% CI, 0.82-0.93; P < .001) and SEER-Medicare (HR, 0.91; 95% CI, 0.85-0.97; P=.002) cohorts.
• After unilateral mastectomy, the estimated 5-year contralateral breast biopsy rates in the commercial insurance and SEER-Medicare cohorts were 10.4% and 7.7%, respectively.
• Subsequent cancer treatment was administered in 1,239 of 4,158 patients (29.8%) in the commercial insurance cohort and 2,258 of 9,747 patients (23.2%) in the SEER-Medicare cohort among the patients with breast biopsy.