Treating advanced breast cancer with metronomic chemotherapy: what is known, what is new and what is the future?

The prognosis for patients with locally advanced or metastatic breast cancer (mBC) remains poor, with a median survival of 2-4 years. About 10% of newly diagnosed breast cancer patients present with metastatic disease, and 30%-50% of those diagnosed at earlier stages will subsequently progress to mBC. In terms of ongoing management for advanced/metastatic breast cancer after failure of hormonal therapy, there is a high medical need for new treatment options that prolong the interval to the start of intensive cytotoxic therapy, which is often associated with potentially serious side effects and reduced quality of life. Oral chemotherapeutic agents such as capecitabine and vinorelbine have demonstrated efficacy in patients with mBC, with prolonged disease control and good tolerability. Use of oral chemotherapy reduces the time and cost associated with treatment and is often more acceptable to patients than intravenous drug delivery. Metronomic administration of oral chemotherapy is therefore a promising treatment strategy for some patients with mBC and inhibits tumor progression via multiple mechanisms of action. Ongoing clinical trials are investigating metronomic chemotherapy regimens as a strategy to prolong disease control with favorable tolerability. This article provides an overview of metronomic chemotherapy treatment options in mBC, with perspectives on this therapy from a panel of experts.