Patterns of Ultraviolet Radiation Exposure and Skin Cancer Risk: the E3N-SunExp Study.
Level 4 - case-series / case-control
Nested case-control study within a prospective cohort
PubMed 29176271 · doi:10.2188/jea.JE20160166
What was done
Researchers conducted a nested case-control study within the French E3N prospective cohort of 98,995 women born between 1925 and 1950. In 2008, a lifetime UV exposure questionnaire was administered to skin cancer cases and controls matched 1:3 on age, birth county, and education. Using conditional logistic regression, they analyzed 366 melanoma cases, 1,027 basal-cell carcinoma (BCC) cases, 165 squamous-cell carcinoma (SCC) cases, and 3,647 matched controls to compare risk profiles across cancer types.
What was found
A history of 6 or more severe sunburns before age 25 was associated with increased risks across all three skin cancers compared to no sunburns: melanoma OR 2.7, BCC OR 1.7, and SCC OR 2.0. Severe sunburns at or after age 25 were associated only with BCC and SCC. High-SPF sunscreen use before age 25 was associated with decreased BCC risk (P trend = 0.02), whereas sunscreen use since age 25 and sunscreen reapplication were associated with elevated risks for all three cancers. Total UV score was positively associated with BCC (P trend = 0.01) and SCC (P trend = 0.09), but not melanoma. Recreational UV exposure was most strongly tied to BCC, whereas residential and total UV exposures were more strongly tied to SCC.
Why it matters
By evaluating melanoma, BCC, and SCC within a single study population, this work demonstrates that skin cancer subtypes have distinct timing and exposure profiles, highlighting early-life sunburns as a shared risk factor while cumulative and residential exposure differentially drive non-melanoma skin cancers.
Limits
The study evaluated only French women born between 1925 and 1950, limiting generalizability to men and other populations. UV exposures and sunburn histories were collected via a retrospective questionnaire in 2008, introducing potential recall bias. Adult sunscreen associations are likely confounded by indication or behavioral compensation.
Cited by
- supports Observational cohort studies show that increased sun exposure increases the risk of developing basal cell and squamous cell carcinomas.