Antitumor activity and safety profile of weekly carboplatin plus paclitaxel in metastatic breast cancer: a ten-year, monocentric, retrospective study

Background: Taxanes are a mainstay in the treatment of metastatic breast cancer (mBC). Combination chemotherapy, including platinum–taxens doublets, can improve tumor responses and progression-free survival (PFS), but is associated with more toxicities and an uncertain benefit in terms of overall survival (OS). Methods: We performed a retrospective study on 274 consecutive patients with mBC treated at the Division of Medical Oncology of Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy, during the decade 2007–2016 with the combination of carboplatin AUC 2 plus paclitaxel 80 mg/m², both given on days 1 and 8 in every 21-day cycle. Results: 264 patients were evaluable for treatment safety and activity. The objective response rate (ORR) was 44.7%. Median PFS and OS were 8.6 and 23.7 months, respectively. Triple-negative breast cancer (TNBC) patients had significantly lower PFS and OS times compared to other biology groups. At multivariable analysis, previous exposure to taxanes, HR-positive HER2-negative biology, a higher number of metastatic sites, and de novo metastatic disease at diagnosis were associated with reduced PFS, while receiving maintenance therapy correlated with improved PFS. Overall, the treatment was quite well tolerated, with 10.2% of patients discontinuing one or both drugs because of adverse events (AEs). G3–G4 neutropenia occurred in 16.8% of patients, while the incidence of febrile neutropenia was 2.3%. Conclusions: Weekly carboplatin–paclitaxel regimen is active and well tolerated in mBC treatment. Prospective studies should be conducted to compare its efficacy and tolerability with standard single-agent paclitaxel or docetaxel treatment schedules, as well as with more recent combination regimens.