A recent review of epidemiologic studies of red meat and prostate cancer determined that 15 of 21 studies found over 30% increased risks associated with higher red meat intakes, six of which were statistically significant--> Kolonel, 2001)
Diets high in red meat also tend to be low in vegetables and track with other unhealthy lifestyle behaviors, which may contribute to the observed associations
Fruits and vegetables have long been studied for their role in cancer prevention because they contain numerous substances with potential anticarcinogenic activity, including folate, carotenoids, flavonoids, vitamins and limonene. In most of these studies, subjects who consume diets high in certain fruits and vegetables have lower risk of some, but not all cancers.
Another interesting fact is that populations with greater exposure to ultraviolet light generally have lower risks of breast--> Garland et al., 1990), colon --> Garland and Garland, 1980 , and prostate cancer --> [Hanchette and Schwartz, 1992).
Lycopene from food is relatively consistently related to an inverse risk of some cancers. Lycopene, the most abundant carotenoid in the plasma in some populations, is not converted to vitamin A and thus may be entirely available for other functions, such as anti-oxidation and quencher of singlet oxygen and free radicals. Lycopene can be found in tomatoes and tomato products, watermelon, and pink grapefruit. In a recent review, 57 of 72 epidemiologic studies reported inverse asociations between tomato intake or blood lycopene level and the risk of specific cancers, with approximately half reporting at least 40% lower risks. Evidence being strongest for cancers of the prostate, lung, and stomach.
Antioxidants may reduce the risk of cancer by neutralizing reactive oxygen species or free radicals that can damage DNA. Vitamin C is the major water-soluble antioxidant, and vitamin E
is the major lipid-soluble membrane-localized antioxidant in humans. Studies of dietary vitamin C support an inverse association, particularly for cancers of the stomach, mouth, esophagus, lung, pancreas, and uterine cervix.--> (World Cancer Research Fund & American Institute for Cancer Research, 1997]
Vitamin E (tocopherol) may help prevent cancer by reducing free-radical damage to DNA and through effects on the immune system. Fats and oils are the major sources of vitamin E and the amount and form varies by type of oil.--> (Institute of Medicine, 2000]
Selenium helps reduce cancer because of its anticarcinogenic role that it plays defending against oxidative stress. The amount of selenium depends greatly on the selenium content of the soil where the plants are grown or the animals raised.
A large European study involving 10 countries found a 25% lower risk of colon cancer associated with higher fiber intakes compared to low intakes.(Bingham et al., 2003a)
I hope you get the point. By eating a plant based diet and eating less red meat you will greatly decrease your odds of getting cancer or other diseases.