Cancer

Skin cancer
AH Conney, et al: Effect of caffeine on UVB-induced carcinogenesis, apoptosis, and the elimination of UVB-induced patches of p53 mutant epidermal cells in SKH-1 Mice. Photochemistry and Photobiology; Epub Jan. 2008.

The authors conclude that "The results of our studies indicate that caffeine and caffeine sodium benzoate are novel sun-protective substances that inhibit carcinogenesis when applied topically to SKH-1 mice either before or after exposure to UVB. Further studies are needed to determine the effects of topical application or oral administration of caffeine and caffeine sodium benzoate on the formation of actinic keratoses and skin cancer in humans."

Epithelial ovarian cancer
S Tworoger, et al: Caffeine, alcohol, smoking, and the risk of incident epithelial ovarian cancer. Cancer; Vol. 112: 2008.

The authors conclude that "The results of the current study suggest that cigarette smoking may only increase the risk for mucinous ovarian tumors, and alcohol intake was not associated with risk. However, an inverse association was observed between caffeine intake and ovarian cancer risk, particularly in women not using hormones; this finding merits further study."