Nationwide study of cutaneous basal cell carcinoma incidence trends in Norway, 2012-2022

Basal cell carcinoma (BCC) is the most common cancer in fair-skinned populations world-wide. However, population-based incidence is rarely reported as most countries do not register BCC. In Norway, melanoma and non-melanoma skin cancers (excluding BCC) are the cancers with the steepest incidence increase since 2000. However, the incidence of BCC remains unknown due to lack of registration.

We aimed to utilise archived pathology reports in the Cancer Registry of Norway (CRN) to estimate the national BCC incidence.

The CRN receives pathology reports for all verified malignant diagnoses. Using those reports, we identified BCCs diagnosed in Norway 2012-2022 and estimated annual person-based (the first pathology report per person only) and tumour-based (first pathology report per person per year) incidence rates. We stratified by sex, age (0-49, 50-59, 60-69, 70-79 and 80 + years) and health regions (south-eastern, western, central and northern Norway). Changes over time were analysed using Poisson regression and expressed as the average annual percentage change (AAPC) with 95% confidence interval (CI). For validation, we estimated person-based melanoma incidence rates using pathology reports and compared with the officially published incidence rates.

During 2012-2022, we identified 70,830 individuals (54.6% women) diagnosed with a first primary BCC (person-based), including 170,308 BCC diagnoses (tumour-based) (52.1% in women). The person-based incidence rate (per 100,000 person-years) increased from 106.8 to 213.3 in women and from 111.6 to 201.3 in men (AAPCs 6.2 (CI: 5.9-6.6) and 6.5 (CI: 6.1-6.8) respectively). Tumour-based rates increased from 242.5 to 421.9 in women (AAPC 4.9 (CI: 4.7-5.1) and from 284.8 to 436.5 in men (AAPC 4.5 (CI: 4.2-4.7)). Steepest increase was seen for ages < 60 years and in the northern region. The estimated melanoma incidence rates, based on pathology reports, were higher than the officially published rates, but differences were small.

During 2012-2022, the BCC incidence almost doubled in Norway. Tumour-based incidence was nearly twofold the person-based, demonstrating that person-level incidence substantially underestimates the BCC burden on healthcare systems, patients, and society. This underscores the need for effective resource planning and prevention strategies.

A high burden of basal cell carcinoma in Norway; Basal cell carcinoma (BCC) is the most common type of skin cancer in fair-skinned populations, but most countries do not routinely record it and thus lack knowledge about its frequency. The Cancer Registry of Norway (CRN) receives reports from pathologists for all confirmed cancer diagnoses in Norway. The BCC reports are archived in the CRN, although not registered. We aimed to utilise these reports to estimate the national incidence rate of BCC. From the reports we identified BCCs diagnosed in Norway between 2012 and 2022. We estimated annual person-based (counting the first pathology report per person) and the tumour-based (counting the first pathology report per person per year) incidence rates by sex, age, and health regions, and the changes in incidence over time. To evaluate our method, we compared the person-based incidence of skin melanoma, based on pathology reports, with the official melanoma rates published from the CRN. During 2012-2022, the BCC incidence rates almost doubled in Norway, with steepest increase in people younger than 60 years and in the northern region. The tumour-based incidence rate was nearly twofold the person-based, demonstrating that the person-level incidence substantially underestimates the BCC burden. Archived pathology reports seem to be a reliable source for estimating incidence of pathologically verified BCC. We found high and increasing BCC incidence rates in Norway, highlighting challenges for the healthcare system in terms of costs, resource allocation, patient morbidity, and the need for effective health planning and preventive strategies.