Abstract S2-03: Early follow up of a randomized trial evaluating resection of the primary breast tumor in women presenting with de novo stage IV breast cancer; Turkish study (protocol MF07-01)

Introduction: Previous reports of carefully selected patients presenting with stage IV breast cancer (BC) suggest that surgery on the primary tumor may result in improved survival, but this remains unproven. The MF07-01 trial is a phase III randomized controlled trial of BC women with distant metastases at presentation who receive loco-regional (LR) treatment for intact primary tumor compared with those who do not receive such treatment. Aim: The primary objective of the trial is to compare overall survival (OS) in women treated with or without initial LR resection prior to systemic therapy for de novo stage IV BC. Materials and Methods: At the discretion of the surgeon, LR treatments consisted of either mastectomy or breast conserving surgery with level I-II axillary clearance in clinically or sentinel lymph node positive patients. Radiation therapy to whole breast was required following breast conserving surgery. At the discretion of the medical oncologist standard systemic therapy of either endocrine treatment or chemotherapy (plus trastuzumab for HER2 +) was given to all patients either immediately after randomization (no surgery group) or after surgical resection of the intact primary tumor (surgery group). After consideration of previous retrospective studies, the assumed OS difference between the two groups was determined to be 18% (35% in LR treatment group versus 17% in no-LR treatment group). A 10% drop out rate including lost to follow up was assumed. By using a one sided log-rank test with a 95% confidence (α = 0.05) and a 90% power (β = 0.9), sample size calculation revealed that 271 patients were needed to be randomized. Results: There were 140 women in the surgery group and 138 in the no-surgery group. The mean follow up time was 21.1 ± 14.5 months. The mean age was 51.6 ± 13.2 years and the groups were comparable regarding age, BMI, ER/PR, Her 2, Triple negative, tumor type and size between the groups (all p>0.05). Metastatic patterns included bone only in 45.7%, organ except bone in 28.8%, and bone plus organ in 25.5%. There were a total of 86 (31%) deaths. At 54 months the survival rate was 35% in the surgery group and 31% in the no surgery group (p = 0.24). However, OS was statistically higher in bone only, ER/PR positive and patients younger than 50 years but was lower in the triple negative patients (p Conclusion: In early follow-up of this trial comparing surgery of the primary tumor with no surgery in stage IV BC at presentation OS was similar but there were important subgroup differences; in particular those with solitary bone metastasis have a significant survival benefit and patients with bone metastasis only have a trend toward improved survival with initial surgery. Further follow-up will expand on these important findings. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S2-03.