Abstract OT3-4-01: A randomized controlled trial comparing primary tumour resection plus systemic therapy with systemic therapy alone in metastatic breast cancer (JCOG1017 study; PRIM-BC)

Abstract A brief background discussion: The efficacy and indication of primary tumour resection for breast cancer patients with distant metastases are under debate. There were many retrospective analysis reports indicating the survival benefit of it. However, the first results of two randomized studies reported in SABCS 2013 could not demonstrate the survival benefit. Nevertheless, the results were not conclusive because the systemic therapy was not uniform (e.g. molecular target therapy) and the diagnostic procedures of metastases was different from the widely accepted guidelines. Trial design: Our trial is being conducted to confirm the superiority, in terms of the overall survival, of surgery plus systemic therapy over systemic therapy alone in stage IV patients who are not refractory to primary systemic therapy (PST). Eligibility criteria: The inclusion criteria for the study are as follows: untreated patients with histologically confirmed invasive breast cancer with one or more measurable distant metastatic lesions diagnosed by radiological examination. Specific aims: All patients receive PST according to the ER and HER2 status of the primary breast cancer after the first registration. After three months, the patients without disease progression are randomized to the primary tumour resection plus systemic therapy arm or the systemic therapy alone arm. After randomization and surgery in the former arm, or after randomization in the latter arm, the same systemic therapies are continued until progression of diseases and next appropriate regimens are started after that. Statistical methods: The primary endpoint is the overall survival, and the secondary endpoints are proportion of patients without tumour progression at the metastatic sites, yearly local recurrence-free survival, proportion of local ulcer/local bleeding, yearly primary tumour resection-free survival, adverse events of chemotherapy, operative morbidity, and serious adverse events. Sample size for randomized patients was determined to attain at least 80% of power to detect a 6 months difference with one-sided alpha of 0.05. Present accrual and target accrual: The patient recruitment was started in May 2011. Enrolment of 410 patients for randomization is planned over a 5-year recruitment period. More than two hundred twenty patients were already enrolled until May 2014. Citation Format: Tadahiko Shien, Hiroji Iwata, Kenichi Nakamura, Takayuki Kinoshita, Fumikata Hara, Tomomi Fujisawa, Norikazu Masuda, Kenichi Inoue, Taro Shibata, Haruhiko Fukuda. A randomized controlled trial comparing primary tumour resection plus systemic therapy with systemic therapy alone in metastatic breast cancer (JCOG1017 study; PRIM-BC) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT3-4-01.