P054 National incidence and survival of extramammary Paget disease 2013–2020 in England: reporting a total of 740 cases

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Abstract Extramammary Paget disease (EMPD) is a rare disease affecting the rich apocrine gland-bearing areas commonly involving the genital and perianal skin. It was first described in 1889 by Radcliffe Crocker. Clinical features of EMPD are insidious and nonspecific, frequently resulting in delayed diagnosis. Diagnosis of EMPD is important due to its association with an underlying malignancy, most commonly urothelial or anorectal, but it may also be cervical, prostatic, ovarian or endometrial in 10–30% cases. Until recently, there were limited national epidemiological data on incidence and survival. National data on EMPD incidence and 5-year survival in England from 2013 to 2020 were extracted from report-level data published openly by the ‘Get Data Out’ National Disease Registration Service programme. Crude incidence rates are reported per 100 000 person-years (PY). Survival is reported as overall Kaplan–Meier survival and net survival with associated 95% confidence intervals (CIs). Data for 2020 vs. 2019 incidence rate ratios with 95% CIs were calculated using the exact Poisson method. In total, 740 new cases of EMPD were diagnosed between 2013 and 2020, with a mean of 93 cases per year. The average crude incidence rate of EMPD per year was 0.17 per 100 000 PY (95% CI 0.14–0.21). The crude incidence rate in 2013 was 0.16 per 100 000 PY (95% CI 0.13–0.20), which increased nonsignificantly in 2019 to 0.20 per 100 000 (95% CI 0.16–0.24). During 2020, the first year of the COVID-19 pandemic, incidence decreased to 0.14 per 100 000 (95% CI 0.11–0.18). The incidence rate ratio between 2020 and 2019 was 0.73 (95% CI 0.54–0.98), with a P-value of 0.03. The 5-year overall Kaplan–Meier survival was 74.1% (95% CI 63.4–82.1) for EMPD diagnosed in 2013. Important limitations include lack of published data on site, age group, depth of invasion and associated comorbidities including malignancies due to small numbers. The reported net survival for EMPD is comparable with that for melanoma and prostate and breast cancer, presumably a result of its association with other underlying malignancies. The increase in crude incidence rates likely represents the ageing population, and one might expect age-standardized rates to be relatively static. The apparent decrease in the crude incidence rate of EMPD during 2020 demonstrates the impact of the pandemic on skin cancer services, as also shown for melanoma and other cancers. A study in the Netherlands assessed 178 cases of invasive and 48 cases of in situ EMPD and found an overall relative 5-year survival of 72% for invasive tumours and an incidence rate of 0.11 per 100 000 PY for EMPD. These data are important in better understanding the trends and outcomes of this rare and poorly understood tumour.

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