James Marshall of the Arizona Cancer Center at the University of Arizona wrote in a commentary. He said it was not a case of the supplements being ineffective, or of the patients not taking their supplements, because blood tests were used to check. Marshall said beta-carotene might be a marker for something else in fruits and vegetables that works to prevent cancer. Research presented earlier this year at a meeting of the American Association for Cancer Research showed that supplements, from ordinary multivitamins to specially formulated vegetable-based capsules, may slow cancer. In one study, a team at the Barbara Ann Karmanos Cancer Institute in Detroit found tomato supplements helped slow prostate cancer in men diagnosed with the disease.
Tomatoes are rich in lycopene, an antioxidant related to beta-carotene.
Another recent study suggests that vitamins such as vitamin C might actually help cancer cells survive chemotherapy and radiation. Dr. David Golde and colleagues at Memorial Sloan-Kettering Cancer Center in New York found cancer cells absorb extra amounts of vitamin C, and may use it to protect themselves from the effects of chemotherapy and radiation. A and E actually had brain tumors that grew more slowly, which they said suggested cancer cells use the vitamins to protect themselves.