Mini-reviewMetronomic chemotherapy: A potent macerator of cancer by inducing angiogenesis suppression and antitumor immune activation

- Metronomic chemotherapy refers to dense and uninterrupted administration of low doses of chemotherapeutic agents.
- Metronomic chemotherapy overcomes drug resistance by shifting the therapeutic target from tumor to endothelial cells.
- Metronomic chemotherapy is probably a multi-targeted cancer therapy rather than a simple anti-angiogenic therapy.
- Metronomic chemotherapy might also restore anticancer immune response and induce tumor dormancy.

Metronomic chemotherapy is a low dosing treatment strategy that attracts growing scientific and clinical interest. It refers to dense and uninterrupted administration of low doses of chemotherapeutic agents (without prolonged drug free intervals) over extended periods of time. Cancer chemotherapy is conventionally given in cycles of maximum tolerated doses (MTD) with the aim of inducing maximum cancer cell apoptosis. In contrast, the primary target of metronomic chemotherapy is the tumor's neovasculature. This is relevant to the emerging concept that tumors exist in a complex microenvironment of cancer cells, stromal cells and supporting vessels. In addition to its anti-angiogenetic properties, metronomic chemotherapy halts tumor growth by activating anti-tumor immunity, thus decreasing the acquired resistance to conventional chemotherapy. Herein, we present a review of the literature that provides a scientific basis for the merits of chemotherapy when administered on a metronomic schedule.