Natural products for chemopreventive and adjunctive therapy in oncologic disease.

Nutritional supplements or complementary and alternative medicines (CAM) are currently being investigated for their use in preventing, inhibiting, and reversing the progression of cancer. Natural agents and their derivatives such as vitamin A, selenium, green tea, resveratrol, aspirin, and probiotics have potential benefits in chemoprevention. There is also growing evidence for the use of natural products as adjunctive therapy alongside conventional cancer treatments. Nutritional supplements expenditures demonstrated greater growth than pharmaceuticals, with approximately 80% of cancer patients using natural products. Current issues with nutritional supplements use in cancer treatment include insufficient or conflicting evidence, poor quality control, potential interactions with chemotherapy, and potential efficacy in relation to changes in certain biomarkers, but long-term implications remain largely unresolved. Continued research is needed to lend credibility to these potentially valuable naturally driven supplements in the prevention and potentially in the treatment of cancer in conjunction with standard pharmaceuticals.