Single-agent trastuzumab versus trastuzumab plus cytotoxic chemotherapy in metastatic breast cancer: a single-institution experience

Trastuzumab has shown significant single-agent activity in patients with Her-2/neu overexpressing metastatic breast cancer, and increased response rates, progression-free and overall survival when added to standard chemotherapy. Despite higher response rates, the combination with chemotherapy has higher toxicity and it remains unknown whether single-agent trastuzumab is equally effective as the combined treatment in terms of progression-free and overall survival. We therefore carried out a retrospective multivariate analysis of 117 patients with Her-2/neu overexpressing metastatic breast cancer who were treated with trastuzumab with or without chemotherapy at a single institution between November 1999 and December 2003. Response rates tended to be higher in patients receiving trastuzumab in combination with chemotherapy (34 versus 8%, p=0.060). However, this did not translate into a benefit in progression-free survival: median (95% confidence interval) progression-free survival was 6.2 (4.45-7.95) months in patients receiving trastuzumab plus chemotherapy versus 4.2 (1.77-6.63) months in those receiving single-agent trastuzumab (p=0.560). Likewise, no significant difference in overall survival was observed: 27.0 (19.9-34.0) versus 23.1 (16.2-30.0) months (p=0.809). We conclude that in the absence of extensive visceral involvement necessitating a higher response rate, single-agent trastuzumab may be a safe and less-toxic alternative to its combined use with other chemotherapy agents. This needs to be confirmed in prospective randomized trials.