Joinpoint regression analysis of incidence and mortality rates for superficial spreading malignant melanoma across diverse demographic characteristics and tumour attributes: a 22-year review of superficial spreading malignant melanoma

Background: In recent years, the incidence and mortality rates of superficial spreading malignant melanoma (SSMM) have significantly increased. However, comprehensive epidemiological studies examining these trends remain scarce. This study aims to explore changes in SSMM incidence and mortality over Twenty-two years. Methods: Data on SSMM patients were extracted from the SEER database, covering incidence and incidence-based mortality. Joinpoint regression analysis was used to calculate the Average Annual Percent Change (AAPC) and 95% confidence intervals (CI). Results: From 2000 to 2021, 131,235 SSMM cases were identified with an age-adjusted incidence rate of 6.98 (95% CI: 6.94-7.01) and an incidence-based mortality rate of 1.33 (95% CI: 1.31-1.34). Males accounted for 54.92% of cases, with 48.82% of patients under 60 years old. Predominantly, SSMM lesions were found on the limbs (46.64%), scalp and neck (14.9%), and trunk (38.47%). SSMM incidence increased significantly (AAPC=2.1%) throughout the study period, while mortality surged sharply from 2000 to 2012 (AAPC=19.9%) before stabilising. The trends varied by sex, age, race, and primary tumor site, with higher rates observed among older individuals, White patients, and those with tumors in sun-exposed areas. Conclusions: The findings reveal a notable increase in SSMM incidence and mortality, with variations across demographic and clinical subgroups. These insights can enhance our understanding of SSMM and support targeted healthcare interventions.