P204 Identifying variations in the ratio of basal cell carcinoma to cutaneous squamous cell carcinoma in England from 2013 to 2022 by demographics and geography

Abstract

Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) are the first and third most common cancers in England. Although they are clinically and pathologically distinct, BCC-to-cSCC ratios are reported inconsistently due to differences in study populations and methods. Standardization allows intermediate comparison within and between populations. We report BCC-to-cSCC ratios stratified by age, gender, deprivation and cancer alliances. Data were extracted from the National Disease Registration Service 2013–22, England. Crude incidence rate ratios (IRRs) per 100 000 persons were analysed using MedCalc software and are reported with Poisson 95% confidence intervals (CIs). Deprivation is reported per the Index of Multiple Deprivation. The national BCC-to-cSCC ratio was 3.31 : 1 (IRR 3.31, 95% CI 2.57–4.31); it was 4.09 : 1 in female patients (IRR 4.09, 95% CI 4.07–4.11) and 2.89 : 1 in male patients (IRR 2.89, 95% CI 2.88–2.90). The ratio is shifting towards cSCC in more recent data: in 2013–2017 it was 3.64 : 1 (IRR 3.64, 95% CI 3.62–3.66) and in 2018–2022 it was 3.04 : 1 (IRR 3.04, 95% CI 3.02–3.05). Among younger people, the ratio shifts towards cSCC. IRRs were 12.5 (95% CI 12.2–12.8) in those aged < 50 years, 5.20 (confidence interval 5.17–5.23) in those aged 50–74 years and 2.28 (95% CI 2.23–2.29) in those aged ≥ 75 years. The incidence is highest in the least deprived quintile, with an IRR favouring BCCs (6.91, 95% CI 6.87–6.95), while the IRR of the most deprived quintile was 6.22 (95% CI 6.16–6.28). The IRR was highest in Mid and South Essex (4.6, 95% CI 3.63–5.94) and lowest in Cornwall and the Isles of Scilly (2.25, 95% CI 1.90–2.69). Evaluating BCC-to-cSCC ratios identifies demographic and geographical variations. However, incidence data stratified by ethnicity and tumour stage are lacking. Inclusion of COVID-19 pandemic years introduces underdiagnosis, particularly for BCC. A reliance on histological data for cancer registration means that tumours treated without histological confirmation are subject to exclusion, more inclined to influence BCC than cSCC. Variations may be explained by differences in sunlight exposure, immune status, clinical practice, age distributions and ethnic composition.