Metronomic therapy: chemotherapy revisited.

Cytotoxic antiproliferative chemotherapeutic agents are the mainstay of treatment in cancers. Chemotherapy is usually administered every 2-3 weeks. Along with acute toxicity and long-term effects of cumulative doses, this strategy potentially allows regrowth of the tumor in the interval period and leads to the emergence of resistant populations of tumor cells. Moreover, even with intense chemotherapy, the outcome is stagnating for most of the tumors. There has been recent interest in the use of chemotherapy in fractionated doses which is far below the maximum tolerated dose. This is called metronomic scheduling of chemotherapy. Here, we review the biology and evidence for metronomic chemotherapy.