Impact of Breast Surgery in Primary Metastasized Breast Cancer: Outcomes of the Prospective Randomized Phase III ABCSG-28 POSYTIVE Trial.

BACKGROUND: Conflicting evidence exists regarding the value of surgical resection of the primary in stage IV breast cancer patients.

OBJECTIVE: The prospective randomized phase III ABCSG-28 POSYTIVE trial evaluated median survival comparing primary surgery followed by systemic therapy to primary systemic therapy in de novo stage IV breast cancer.

METHODS: Between 2011 and 2015, 90 previously untreated stage IV breast cancer patients were randomly assigned to surgical resection of the primary tumor followed by systemic therapy (Arm A) or primary systemic therapy (Arm B) in Austria. Overall survival (OS) was defined as the primary study endpoint.

RESULTS: The trial was stopped early due to poor recruitment. Ninety patients (45 arm A, 45 arm B) were included; median follow-up was 37.5 months. Patients in the surgery arm had more cT3 breast cancer (22.2% vs 6.7%) and more cN2 staging (15.6% vs 4.4%). Both groups were well balanced with respect to the type of first-line systemic treatment. Median survival in arm A was 34.6 months, versus 54.8 months in the nonsurgery arm [hazard ratio (HR) 0.691, 95% confidence interval (95% CI) 0.358-1.333; P = 0.267]; time to distant progression was 13.9 months in the surgery arm and 29.0 months in the nonsurgery arm (HR 0.598, 95% CI 0.343-1.043; P = 0.0668).

CONCLUSION: The prospective phase III trial ABCSG-28 (POSYTIVE) could not demonstrate an OS benefit for surgical resection of the primary in breast cancer patients presenting with de novo stage IV disease.