Smoking has been a proven carcinogenic risk factor for various cancers, including breast cancer. Furthermore, smoking has been recognized as a prognostic factor of breast cancer. Bevacizumab is a monoclonal antibody to vascular endothelial growth factor (VEGF) used in combination with chemotherapy to treat breast cancer. We, herein, investigated the effect of smoking on the prognosis of unresectable breast cancer patients who received bevacizumab plus weekly paclitaxel.

From April 2011 to June 2022, 131 patients received bevacizumab plus weekly paclitaxel for unresectable breast cancer. At their first visit to our hospital, smoking status (i.e., period of smoking and amount of smoking per day) was evaluated by interview, and packs-years were calculated.

Time to treatment failure (TTF) was significantly longer in the high packs-years group than the low packs-years group (p=0.010, log-rank). The log-rank test showed that the high packs-years group had a significantly longer overall survival than the low packs-years group (p=0.049, log-rank). Multivariate analysis of TTF revealed that progesterone receptor (p=0.005, HR=0.408) and packs-years (p=0.007, HR=0.391) were independent factors.

A history of smoking may impact prognosis of combination chemotherapy with bevacizumab for advanced breast cancer treatment.