Low-Dose Metronomic Chemotherapy in Metastatic Breast Cancer: A Retrospective Analysis of 40 Patients

Abstract

Purpose: Low-dose metronomic chemotherapy is an emergent treatment schedule in which low doses of cytotoxic agents are given orally continuously, with no or short drug-free intervals. In general , it provides better tolerance, especially in patients who have been previously exposed to other oncologic treatments, with a favorable cost-effectiveness profile. It is well known that all these low-dose schedules have a favorable safety profile and may provide an adequate tumor control in patients with metastatic breast cancer. However, there are no data in literature reporting the patient’s tolerance and response to subsequent lines of chemotherapy after receiving metronomic regimens. Methods: We retrospectively analyzed 40 patients with metastatic breast cancer treated with low doses of Cyclophosphamide and/or Methotrexate and/or Capecitabine in a single center from June 2009 to April 2014. The following data were collected: age, hormone and epidermal growth factor receptor 2 (HER-2) status, number of lines of chemotherapy prior to and after low-dose metronomic treatment, duration of metronomic treatment, toxicity reason for treatment discontinuation. Duration of low-dose metronomic chemotherapy was also correlated with the variables analyzed and treatment outcomes. Results: The median time on metronomic chemotherapy was 5.4 months. The most frequent drugs administered were cyclophosphamide, methotrexate and capecitabine alone. Asthenia, myelotoxicity, gastrintestinal symptoms and handfoot syndrome were the most commonly recorded treatment related toxicity. Twenty six (65%) patients had the opportunity to receive a classic chemotherapy regimen following metronomic regimen interruption. Although patients who developed toxicity to low-dose metronomic chemotherapy remained less time (<6 months) in subsequent chemotherapy, there was no statistically significant difference among those who received more lines of chemotherapy. Discussion: This is the first report in the literature describing the efficacy of low-dose metronomic regimens and the tolerance to subsequent lines of treatments following a period of metronomic chemotherapy. Most of our patients were able to tolerate conventional chemotherapy regimens administered in full doses. Several patients received as many as three lines of additional chemotherapy for periods that exceeded 6 months of treatment, which suggest s that the use of prolonged metronomic treatment d oes not affect a patient’s ability to tolerate subsequent therapy.