To evaluate the effect of different first-line chemotherapy durations in patients with metastatic breast cancer (MBC) on overall survival (OS) and progression-free survival (PFS).

We searched literature databases to identify randomized controlled trials that compared different chemotherapy durations in the first-line treatment of MBC. Only trials with unconfounded comparisons of additional cycles of chemotherapy were included. The main outcome measures for this analysis were OS and PFS. Published data from retrieved studies were analyzed according to standard meta-analytic techniques.

We found 11 randomized clinical trials including 2,269 patients. Longer first-line chemotherapy duration resulted into a significantly improved OS (hazard ratio [HR], 0.91; 95% CI, 0.84 to 0.99; P = .046) and PFS (HR, 0.64; 95% CI, 0.55 to 0.76; P < .001). There were no differences in effects on either OS or PFS between subgroups defined by time of random assignment, study design, number of chemotherapy cycles in the control arm or concomitant endocrine therapy.

Longer first-line chemotherapy duration is associated with marginally longer OS and a substantially longer PFS.