In standard chemotherapy, the goal is to kill cancer cells by administering the highest possible doses. However, these doses can cause more side effects. In recent years, it has been shown that lower doses of chemotherapy can still kill cancer cells with fewer side effects (1-5). This allows patients to continue their daily lives like other normal people while receiving treatment. The main characteristics and differences between metronomic chemotherapy and standard chemotherapy are as follows (1-6):

• Continuous treatment without any breaks.
• Using biologically optimized low doses instead of the maximum tolerated dose (MTD) used in standard chemotherapy.
• There is no need for bone marrow growth factors.
• Preference for oral medications.
• Very few treatment-related side effects.
• Development of drug resistance in cancer occurs later compared to standard chemotherapy.
• Standard chemotherapy is given every 1-2-3 weeks, while metronomic chemotherapy can be administered orally on a daily basis.
• Standard chemotherapy affects fast-dividing cells, including cancer cells, while metronomic chemotherapy affects the endothelial cells in the blood vessels that nourish the cancer mass.
• Standard dose chemotherapy causes more side effects and needs more supportive treatment. Metronomic chemotherapy causes fewer side effects and needs less supportive treatment.
• Standard dose chemotherapy requires hospital visits, while many metronomic chemotherapy treatments do not require hospital visits.
• The number and function of Treg cells, which suppress the immune system, are reduced by metronomic chemotherapy, which stimulates the anti-cancer immune system. In addition, metronomic chemotherapy increases the benefit of cancer vaccines.

Reference:

• Banna GL, Camerini A, Bronte G, Anile G, Addeo A, Rundo F, Zanghì G, Lal R, Libra M. Oral Metronomic Vinorelbine in Advanced Non-small Cell Lung Cancer Patients Unfit for Chemotherapy. Anticancer Res. 2018 Jun;38(6):3689-3697.
• Ueno T, Masuda N, Kamigaki S, et al. A multicenter phase II trial of neoadjuvant letrozole plus low‐dose cyclophosphamide in postmenopausal patients with estrogen receptor‐positive breast cancer (JBCRG‐07): therapeutic efficacy and clinical implications of circulating endothelial cells. Cancer Medicine. 2018;7(6):2442-2451.
• Cho E, Wu Q, Rubinstein L, Linden H, Gralow J, Specht J, Gadi V, Ellis G. Adjuvant continuous metronomic adriamycin + cyclophosphamide followed by weekly nab-paclitaxel for high-risk early-stage breast cancer. Breast J. 2018 Jul;24(4):610-614.
• Petrizzo A, Mauriello A, Luciano A, et al. Inhibition of tumor growth by cancer vaccine combined with metronomic chemotherapy and anti-PD-1 in a pre-clinical setting. Oncotarget. 2018;9(3):3576-3589.
• Maiti R. Metronomic chemotherapy. Journal of Pharmacology & Pharmacotherapeutics. 2014;5(3):186-192.
• Tongu M, Harashima N, Monma H, et al. Metronomic chemotherapy with low-dose cyclophosphamide plus gemcitabine can induce anti-tumor T cell immunity in vivo. Cancer Immunol Immunother. 2013 Feb;62(2):383-91.