In 1997, Jang reported that topical resveratrol applications prevented the skin cancer development in mice treated with a carcinogen. There have since been dozens of studies of the anti-cancer activity of resveratrol in animal models. No results of human clinical trials for cancer have been reported. However, clinical trials to investigate the effects on colon cancer and melanoma (skin cancer) are currently recruiting patients.
In vitro resveratrol interacts with multiple molecular targets (see the mechanisms of action), and has positive effects on the cells of breast, skin, gastric, colon, esophageal, prostate, and pancreatic cancer, and leukemia. However, the study of pharmacokinetics of resveratrol in humans concluded that even high doses of resveratrol might be insufficient to achieve resveratrol concentrations required for the systemic prevention of cancer. This is consistent with the results from the animal cancer models, which indicate that the in vivo effectiveness of resveratrol is limited by its poor systemic bioavailability. The strongest evidence of anti-cancer action of resveratrol exists for tumors it can come into direct contact with, such as skin and gastrointestinal tract tumors. For other cancers, the evidence is equivocal, even if massive doses of resveratrol are used.
Thus, topical application of resveratrol in mice, both before and after the UVB exposure, inhibited the skin damage and decreased skin cancer incidence. However, oral resveratrol was ineffective in treating mice inoculated with melanoma cells. Resveratrol given orally also had no effect on leukemia and lung cancer; however, injected intraperitoneally, 2.5 or 10 mg/kg of resveratrol slowed the growth of metastatic Lewis lung carcinomas in mice. Resveratrol (1 mg/kg orally) reduced the number and size of the esophageal tumors in rats treated with a carcinogen. In several studies, small doses (0.02-8 mg/kg) of resveratrol, given prophylactically, reduced or prevented the development of intestinal and colon tumors in rats given different carcinogens.
Resveratrol treatment appeared to prevent the development of mammary tumors in animal models; however, it had no effect on the growth of existing tumors. Paradoxically, treatment of pre-pubertal mice with high doses of resveratrol enhanced formation of tumors. Injected in high doses into mice, resveratrol slowed the growth of neuroblastomas.