The Impact of Primary Tumor Surgery on Survival in HER2 Positive Stage IV Breast Cancer Patients in the Current Era of Targeted Therapy

Objective We sought to examine the impact of primary tumor resection on survival in HER2+ stage IV breast cancer patients in the era of HER2 targeted therapy. Methods We conducted a retrospective cohort study of women with HER2+ stage IV breast cancer in the National Cancer Database from 2010 to 2012 comparing those who did and did not undergo definitive breast surgery. Results Of 3231 patients, treatment included primary site surgery in 35.0%; chemo/targeted therapy in 89.4%; endocrine therapy in 37.7%; and radiation in 31.8%. Surgery was associated with Medicare/other government (OR 1.36, 95% CI 1.03–1.81) or private insurance (OR 1.93, 95% CI 1.53–2.42) versus none/Medicaid, radiation (OR 2.10, 95% CI 1.76–2.51), chemo/targeted therapy (OR 1.99, 95% CI 1.47–2.70), and endocrine therapy (OR 1.73, 95% CI 1.40–2.14). Non-Hispanic Black versus White patients (OR 0.68, 95% CI 0.53–0.87) were less likely to have surgery. Overall mortality was associated with insurance (Medicare/other government versus none/Medicaid, HR 0.36, p < 0.0001), receipt of chemo/targeted therapy (HR 0.76, p = 0.008), endocrine therapy (HR 0.70, p = 0.0006), and radiation therapy (HR 1.33, p = 0.0009), NH Black versus White race/ethnicity (HR 1.39, p = 0.002), visceral versus bone-only metastases (HR 1.44, p = 0.0003), and lowest versus highest income quartile (HR 1.36, p = 0.01). Propensity score analysis showed surgery was associated with improved survival versus no surgery (HR 0.56, 95% CI 0.40–0.77). Conclusions Surgery of the primary site for metastatic HER2+ breast cancer is associated with improved overall survival in selected patients.