LAUSR

Melanoma is a growing problem worldwide, but it is a malignancy that shows striking differences in incidence, mortality and survival rates across populations. This marked international variability supports the important role of cancer prevention (primary, secondary and tertiary) as a means to reduce future burden. Population-based cancer survival is a key metric used to evaluate the overall effectiveness of melanoma control programmes. In this issue of the BJD, Di Carlo and colleagues from the CONCORD Working Group report the findings of the largest analysis to date of melanoma survival (2000–2014), including data from 284 cancer registries across 59 countries from Africa (4) Central and South America (9), North America (2), Asia (13), Europe (29) and Oceania (2), specifically evaluating the prognostic role of morphology. Their findings provide a global perspective on melanoma survival and highlight several important disparities. The distribution of melanoma morphology varies by continent and country. Nodular and acral lentiginous melanomas are most common in populations with predominantly dark skin; superficial spreading melanomas are most common in populations with predominantly fair skin. Di Carlo et al. reported the lowest 5-year net survival for the nodular and acral lentiginous subtypes, contributing to lower overall survival in Asia and in Central and South America where these subtypes are over-represented. As differences in survival between populations may be because of differences in stage of disease at diagnosis, Di Carlo et al. performed subgroup analyses using data from registries with complete information on stage and morphology; the lower survival for nodular and acral lentiginous melanoma persisted after adjustment for sex, age and stage of disease at diagnosis. Survival from superficial spreading melanoma was lower in Asia and eastern Europe compared with other regions. The proportion of melanomas of the superficial spreading subtype generally increased over time; however, survival from superficial spreading melanoma improved. The latter observation likely reflects a shift towards the diagnosis of thinner lesions as a result of heightened early detection activities. Long-term surveillance of global trends in melanoma incidence and mortality rates form the basis of estimates of the cancer burden used to establish priorities for melanoma control programmes. High-quality data from cancer registries is seen as the gold standard for these comparisons; however, variation in cancer registration practices across registries and countries can limit the interpretation of observed trends. Di Carlo and colleagues have highlighted the issue of incomplete pathological reporting of melanoma morphology; a high proportion (overall 43%) of melanomas were registered as morphology ‘not otherwise specified’. Although the benefits of pathological reporting of morphology in terms of patient management are debated (as treatment options do not differ between histological subtypes at a given stage at diagnosis), the benefit for population-based research and reporting cannot be disputed. The work of the CONCORD consortium is a powerful example of synthesized evidence that can highlight differences and provide important insights; the breadth of international collaboration is commendable. The study by Di Carlo and colleagues will provide a baseline against which countries can monitor the progress of their melanoma control efforts.