Improved survival for melanoma in Northern Ireland: a comparison of two 5-year periods (1984-88 and 1994-98).

Background: The incidence of cutaneous malignant melanoma has been rising steadily in Caucasian populations for several decades, with a doubling time of 10-14 years. An increase in incidence of about 5% per year has been reported in most Caucasian populations since the early 1960s.

Objectives: This study was designed to determine the changing incidence of primary cutaneous malignant melanoma in Northern Ireland and to examine changes in survival rates from cutaneous malignant melanoma in two 5-year periods, 1984-88 and 1994-98.

Methods: One thousand three hundred and twenty-six patients with invasive primary cutaneous melanoma were included in the study.

Results: The age standardized rate of melanoma rose from 4.3 per 100,000 population per year in men and 8.6 per 100,000 population per year in women to 7.7 and 11.8, respectively, per 100,000 population per year in the 1994-98 period. Overall, the absolute 5-year survival for the 1984-88 period was 71.0% [95% confidence interval (CI) 66.9-75.1%] and 77.4% (95% CI 73.4-81.4%) for the 1994-98 period. Women consistently showed better survival at all ages and within almost all categories of thickness of primary tumour. Younger patients of both sexes showed better survival rates.

Conclusions: When survival rates between the 1984-88 and 1994-98 periods were compared using multivariate analysis, we found that patients diagnosed in the second period had a one-third lower risk of dying than those in the earlier period. Much of this reduction was explained by changes in the number of melanomas of thin Breslow depth and ulcerated melanomas.