About the Cover
Cover image

The latitudinal gradient of cancer morbidity, in particular for breast cancer, has been known for ¾ century to correspond inversely with ambient sunlight and its mechanism has been attributed for the past nearly 4 decades to sunlight's production of cancer-inhibiting vitamin D3 in the skin. Makarova et al (page 383) have tested the anti-cancer effects of ultraviolet irradiation and D3 in a murine cancer model in which large T antigen expressed in the mammary gland drives fatal mammary gland carcinogenesis. They have found that in this model UVR does delay and reduce tumor progression, that vitamin D3 administration, whether given systemically or applied topically to the skin, has no such effect, and that the effects of UVR persist in mice unable to produce D3 on exposure to UVR. The authors suggest that identification of the non-D3, UV-induced molecule that transmits the anti-cancer effect from the skin to the mammary gland might uncover novel approaches for prevention of extra-cutaneous human cancer. On the cover is an image of a murine mammary gland with DCIS, treated with UV, and stained to display (black) expression of the large T antigen.