Metronomic chemotherapy of cyclophosphamide plus methotrexate for advanced breast cancer: Real-world data analyses and experience of one center.

BACKGROUND

Real-world data of the CM regimen [cyclophosphamide (CTX) plus methotrexate (MTX)] in metronomic pattern for advanced breast cancer is limited to small-sample or retrospective studies. This study was aimed to determine the effectiveness and safety of CM regimen in treating advanced breast cancer and to identify which patients are most likely to benefit from metronomic CM regimen.

METHODS

Patients with advanced breast cancer who received the metronomic CM regimen at least once between January 2009 and February 2019 in Sun Yat-sen University Cancer Center were included. Clinicopathological characteristics were collected. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier estimates. Characteristics between patients with PFS < 6 months and ≥6 months were compared using the Chi-square test. Univariate and multivariate Cox regression model was used to estimate the prognostic factors for PFS and OS.

RESULTS

A total of 186 patients were included. The median age and follow-up were 49 years and 13.3 months, respectively. Over 50% of the patients were estrogen receptor/progesterone receptor-positive, and 60.8% had been heavily treated (≥3 lines). The objective response rate was 3.8%, the disease control rate at 12 weeks was 41.4%, and the clinical benefit rate at 24 weeks was 31.2% (58/186). The median PFS was 4.0 months [95% confidence interval (CI): 3.6-4.7 months], the median duration of clinical benefit was 9.5 months (95% CI: 8.2-10.8 months), and the median OS was 26.8 months (95% CI: 20.9-37.7 months). Multivariate analysis for PFS revealed the CM regimen as maintenance therapy and no liver metastasis as favorable prognostic factors. Furthermore, patients without liver metastasis were more likely to have a PFS over 6 months than those with liver involvement (P = 0.022). Liver, lymph node, and brain metastases were unfavorable prognostic factors for OS. The CM regimen was well-tolerated without newly reported adverse events.

CONCLUSIONS

The CM regimen was effective in selected patients. In clinical practice, it would be better used as maintenance therapy and in patients without liver metastasis. Further follow-up investigation should be performed to examine its effect when used in combination with other treatments and determine predictive biomarkers.