Background: Despite an increase in incidence of basal cell carcinoma (BCC) among young people and the ubiquity of indoor tanning in this population, few epidemiologic studies have investigated this exposure-disease relationship.

Objective: We sought to evaluate the association between indoor tanning and early-onset BCC.

Methods: Patients with BCC (n = 376) and control subjects with minor benign skin conditions (n = 390) who were younger than 40 years of age were identified through Yale Dermatopathology. Participants provided information on ever indoor tanning, age of initiation, frequency, duration, burns while tanning, and type of tanning device during an in-person interview. We calculated odds ratios (OR) and 95% confidence intervals (CI) using multivariate logistic regression with never indoor tanners as the referent group.

Results: Ever indoor tanning was associated with a 69% increased risk of early-onset BCC (95% CI 1.15-2.48). This association was stronger among females (OR 2.14, 95% CI 1.31-3.47), for multiple BCCs (OR 2.16, 95% CI 1.26-3.70), and for BCCs on the trunk and extremities (OR 2.81, 95% CI 1.57-5.02). Risk increased dose dependently with years using regular indoor tanning devices (P trend = .003), number of overall burns (P trend < .001), and burns to biopsy site (P trend < .001) from indoor tanning. Approximately one quarter (27%) of early-onset BCCs (or 43% among women) could be prevented if individuals never tanned indoors.

Limitations: Potential recall bias of indoor tanning by patients and generalizability of the control population suggest replication in other studies is warranted.

Conclusions: Indoor tanning was a strong risk factor for early-onset BCC, particularly among females. Indoor tanning should continue to be targeted by both policy-based and behavioral interventions, as the impact on BCC-associated morbidity may be substantial.