Introduction/Background There is a growing importance of low-dose metronomic chemotherapy (LDMC) in metastatic breast cancer (MBC). In this retrospective case-control-analysis we compared the efficacy of LDMC and conventional chemotherapy in MBC.

Methodology Each LDMC patient receiving oral cyclophosphamide (CTX) (50 mg daily) and methotrexate (MTX) (2.5 mg every other day) was matched with two patients who received conventional chemotherapy. Age, number of chemotherapy lines and metastatic lesions as well as hormone receptor (HR) status were considered as matching criteria. Primary endpoint was disease control rate greater than 24 weeks (DCR). Secondary endpoints were DCR in subgroups (age at begin of therapy, number of chemotherapy lines, number of different metastatic lesions and HR status), progression-free survival (PFS) and duration of response (DoR).

Results A total of 40 cases and 80 controls entered the study. 30% patients with LDMC and 23% patients with conventional chemotherapy showed DCR (p=0.380). Among younger patients DCR was 40% in LDMC vs. 25% in the control group (p=0.249). In addition, DCR was achieved in 33% vs. 26% patients with ≤ 2 chemotherapy lines (p=0.568) and in 36% vs. 18% patients with ≤ 2 different metastatic lesions (p=0.096), respectively. In the triple negative group 30% LDMC vs. 5% control patients showed DCR (p=0.095). The median PFS was 12.5 weeks in both groups (p=0.218). The median DoR was 31 weeks in LDMC and 21 weeks in the control group (p=0.383).

Conclusion In this retrospective case-control study we demonstrated a similar efficacy of LDMC compared to conventional chemotherapy in the treatment of MBC. Moreover, no significant differences were found in the subgroups studied. Therefore, the concept of LDMC may also be a treatment option in both younger and non-heavily pre-treated MBC patients who do not need rapid remission.

Disclosure Nothing to disclose.