A retrospective cohort study of melanoma prevalence stratified by body site in a Regional Australian Population 1994-2017: Site-specific protective mechanisms

摘要

Background Australia has the highest incidence of cutaneous melanoma worldwide. Previous studies have identified some body areas (forearms and dorsal hands) have lower rates of melanoma than expected when compared with other similarly exposed areas, leading to the suggestion that endogenous immunological protective mechanisms in certain body sites may exist. Aims and Methods We hypothesise that examination of melanoma by body site in a regional Australian setting would demonstrate no significant variation in the incidence of melanoma across highly sun exposed areas including the head and neck and upper limbs. Results were stratified by body site and further examined by univariate correlation analysis by gender, age, body site, Breslow thickness and subtype. Polytomous logistic regression was used to test the difference in risk factors by location of melanoma. Results A total of 772 melanomas were included in the analysis. Melanomas of the upper limb were more likely to affect females (OR = 2.415 95%CI: 1.433-4.072) and more likely to be thinner than other body sites. Compared to other international studies, statistically significant decreased rates of melanoma were seen on the upper limb compared to other areas of the body (X-2 = 16.29, P < 0.001). Examination of sites of melanoma on the upper limb showed significantly decreased rate on the distal upper limb given relative body surface areas (X-2 = 6.30 P = 0.04). Discussion and Conclusions Our study was limited by its retrospective nature, and the findings require validation in a larger prospective cohort. Further exploration of such mechanisms may lead to new insights into the immunological mechanisms surrounding cutaneous melanoma.