Differences in site-specific incidence and relative survival of cutaneous and mucocutaneous genital squamous cell carcinoma in Germany, 2007-2015.

Direct comparisons of the incidence and survival of cutaneous vs mucocutaneous genital squamous cell carcinomas (SCCs) are lacking even though they may bring important insights. We aimed to compare incidence rates and survival of cutaneous and mucocutaneous genital SCCs head-to-head, using the same source population, cancer registry methodology and statistical methods in a population of predominantly white Caucasian descent. Using data (2007-2015) from the population-based cancer registry of North Rhine-Westphalia, (population of 18 million people), we estimated age-specific and age-standardized (old European standard) incidence rates and age-standardized relative 5-year survival of SCC with the period approach for the period 2012 to 2015. Overall, 83 650 SCC cases were registered. The age-standardized incidence rates (per 100 000 person-years) of cutaneous SCCs were 36.5 (SE 0.17) and 17.0 (SE 0.11) among men and women, respectively, with corresponding rates for mucocutaneous genital skin, 1.3 (SE 0.03) and 4.5 (SE 0.06) for men and women, respectively. In all age groups, incidence rates of mucocutaneous genital SCCs were higher in women than men. Men had higher cutaneous SCC incidence at all nongenital subsites than women, with the exception of the lower extremities. Five-year relative survival was considerably lower for mucocutaneous genital SCCs (men: 71%, women: 75%), especially of the scrotal skin (67%) and labia majora (62%) than for SCC of nongenital skin (men: 93%, women: 97%). Given their relatively high incidence together with a lower survival probability, future studies are warranted to establish therapies for advanced mucocutaneous genital SCC, such as immune checkpoint inhibition.