Period and cohort factors in the incidence of malignant melanoma in the state of Connecticut.

The reasons for the increase in both incidence and mortality from malignant melanoma are not clear at this time, although there is an indication of a "generation effect" in the increasing frequency of the disease. The application of an age-period-cohort model to incidence data on malignant melanoma for the State of Connecticut indicate that, unlike mortality, the increase is almost entirely related to period factors. Two explanations are provided to explain this pattern of period factor increase. First, the increase in incidence could be artifically produced by better and earlier diagnosis. Second, a decrease in ozone level in the atmosphere may be responsible for the increase.