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This was on the Mayo Clinic Site.
Metronomic chemotherapy: Low-dose chemotherapy for advanced cancers
Metronomic chemotherapy delivers lower doses of chemotherapy more often, causing fewer side effects. Researchers hope it can one day improve cancer treatment.
It seems contrary to current cancer therapy, but cancer researchers are investigating whether smaller doses of chemotherapy drugs could be more effective in certain situations. Researchers call it metronomic chemotherapy, referring to the steady schedule of chemotherapy doses. And they're finding that in the case of some people with advanced cancers or cancer that has become resistant to chemotherapy, less may be more successful.
Traditional chemotherapy treatment delivers the highest doses possible to kill cancer cells. Along with large doses come significant side effects. Metronomic chemotherapy aims to lessen the side effects of treatment while rendering cancer cells inactive. Researchers hope metronomic chemotherapy will one day make cancer a manageable chronic condition.
What is metronomic chemotherapy?
Metronomic chemotherapy uses traditional chemotherapy drugs in a new way. Rather than receiving the largest dose of chemotherapy possible, people undergoing metronomic chemotherapy receive as little as one-tenth the normal dose. Smaller doses are less damaging to healthy cells in the body, so chemotherapy can be administered more frequently — sometimes every day.
People undergoing traditional chemotherapy treatment usually wait weeks between treatments to let their healthy cells recover. For instance, you may need to wait until your blood counts are restored to acceptable levels before you can receive your next chemo treatment. Unfortunately this interval between treatments also allows the cells that help supply oxygen and nutrients to a tumor (endothelial cells) time to heal and regenerate so they can revive the cancer cells.
Metronomic chemotherapy targets the tumor's endothelial cells, rather than the cancer cells. Endothelial cells are found in the tumor's blood vessels. By killing the endothelial cells, the blood supply is cut off. Without a blood supply, cancer cells may die or the tumor may shrink. Tumors without blood supplies remain very small — usually less than 3 millimeters.
A drug that alters the blood supply to a tumor is called an angiogenesis inhibitor. Angiogenesis refers to the process of growing blood vessels. Metronomic chemotherapy is sometimes called anti-angiogenic chemotherapy.
Traditional chemotherapyMetronomic chemotherapyDose Highest possible doseOne-tenth to one-third of the traditional doseWait between doses WeeksDaysCells targeted Cancer cellsEndothelial cells that provide nutrients to tumorGoal of treatment Kill cancer cellsStop endothelial cells from supporting the cancer cellsMost useful for Adjuvant therapy for people with early-stage cancers, or certain rapidly growing chemotherapy-sensitive tumorsLarge tumors that can't be removed through surgery, or cancer that has spread
What are the advantages of metronomic chemotherapy?
Metronomic chemotherapy lessens the severity of the side effects caused by traditional chemotherapy. Although side effects aren't completely eliminated, they're generally more tolerable when chemotherapy is administered in smaller doses.
Metronomic chemotherapy can be used in people whose cancers are resistant to chemotherapy. Because cancer cells are constantly mutating, they may become resistant to chemotherapy drugs. When this occurs, high-dose chemotherapy is no longer effective. But endothelial cells are genetically stable, which means they don't mutate and can't become drug resistant. Even though a drug may no longer be effective against cancer cells, the same drug can still be useful in targeting the endothelial cells.
Metronomic chemotherapy may also enhance the effects of angiogenesis inhibitors — drugs that alter the blood supply to tumors. Only one angiogenesis inhibitor is currently approved for use in cancer, but researchers are working on several more. The combination of drugs may one day work together to halt the supply of oxygen and nutrients to tumors.
How is metronomic chemotherapy being studied?
Researchers are investigating metronomic chemotherapy in clinical trials for a variety of different cancers. Most trials pair metronomic chemotherapy with an angiogenesis inhibitor. Some studies have shown that together, the two types of drugs are more likely to cause tumors to shrink.
Researchers are also investigating metronomic chemotherapy as a maintenance therapy given after initial treatment. For instance, you might receive standard treatments to shrink your cancer to a manageable size and then take daily metronomic chemotherapy to keep the cancer in check.
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