Studies indicate that one-third of cancer patients take combinations of medications (both prescribed and non-prescription/over-the-counter drugs) that place them at risk of potentially dangerous interactions. (Read More Here)
This number may actually be far greater after accounting for the widespread use of dietary supplements, including high-dose vitamins and various botanical/herbal therapies. To make matters even more confusing, studies have demonstrated potentially serious interactions that can occur when consuming certain foods (i.e. grapefruit) while taking medications that are metabolized by the liver.
Drug-drug interactions, drug-supplement interactions and drug-food interactions can range from minor interactions that have little to no noticeable effects to potentially life-threatening complications (i.e. decreased effectiveness or increased toxicity of chemotherapy, increased risk of seizures, bleeding, blood clots, stomach ulcers, heart attack, stroke, cardiac arrhythmia, etc.) The severity of these interactions depends on a wide-range of variables that need to be taking into account for each patient (i.e. route of administration, dose, timing, body weight, co-existing medical conditions, etc.)
One of the best resources available (and it is FREE) for learning about potential drug-supplement interactions is an up to date, searchable online database, maintained by the Integrative Medicine Service, of the Memorial Sloan-Kettering Cancer Center (About Herbs, Botanicals and Other Products.) Other reference sources (subscription and/or free) are widely available through the internet, including the American Cancer Society, U.S. National Cancer Institute, Natural Standard, etc.
As an integrative oncologist, I spend a great deal of time with my patients reviewing all of their medications, supplements and diet. This is one of the more important aspects of overall cancer care, and one that I strongly encourage anyone with cancer to discuss with their health care team.