Taxane-based mono- or combination therapy for managing metastatic breast cancer (MBC) in routine practice: a multinational prospective observational study.

Objectives: Taxanes are standard for first-line chemotherapy of metastatic breast cancer (MBC), but indications for single-agent versus combination treatment remain controversial. This non-interventional study in 12 different countries explored treatment patterns and progression-free survival (PFS) in routine practice. Research design and methods: The prospective study was designed to determine factors associated with the choice of taxane-based regimens for MBC. Data were collected at the start of first-line treatment planned by the physician (baseline), and at subsequent routine practice visits. Patients were followed up until death, disease progression or change of treatment regimen, for a maximum of 8 months. Upon analysis, patients were classified into taxane single-agent (TM) or taxane-based combination (TC) cohorts according to scheduled first-line therapy. Logistic regression was used to investigate the relationship between choice of TM vs. TC and baseline factors. Results: Among the 465 patients enrolled (22.4% HER2+), 160 were prescribed TM (69% docetaxel, 31% paclitaxel) and 305 TC, frequently combined with gemcitabine (39%) or capecitabine (24%). HER2+ status was the only factor associated with choosing TC (p<0.001). Median PFS [95% CI] was 11.5 [8.7-13.3] months for TM and 10.3 [8.4-14.4] months for TC. Among HER2+ patients (N=104), only 59% received trastuzumab, none had previous adjuvant trastuzumab. Median PFS was 19.7 [9.3-unestimated] months for TC including trastuzumab, 18.8 [5.0-22.0] months for TC and 6.1 [3.8-13.3] months for TM without trastuzumab. Conclusions: In patients from 12 different countries treated during routine practice, TCs were prescribed more frequently than single agents. HER2+ status was significantly associated with TC use. 41% of HER2+ patients received no anti-HER2 treatment; PFS results for TC with and without trastuzumab (19.7 and 18.8 months) suggested TCs without trastuzumab might be worth further investigation in these patients. However, the study was not randomized; treatment evaluation bias can therefore not be excluded.