Immunity and skin cancer.

Observations in humans and animal studies support the theory that immunologic surveillance plays an important role in limiting the development of skin malignancies. These immune responses undergo progressive diminution with age. In addition, other factors, such as bereavement, poor nutrition, and acute and chronic exposure to ultraviolet light, can further diminish immune mechanisms. We believe these decreases in immune function in combination with the carcinogenic effect of ultraviolet light are important in the production of skin cancers.