Laboratory and epidemiologic studies suggest that certain dietary supplements may alter risk of cutaneous squamous cell carcinoma (SCC).Objective
We sought to examine the association between supplement use and SCC risk.Methods
Cases (n = 415) were defined as Kaiser Permanente Northern California members with a pathology-verified SCC in 2004 and control subjects (n = 415) were age-, sex-, and race-matched members with no history of skin cancer. Supplement use and SCC risk factors were ascertained by questionnaire. Associations of SCC with use of multivitamins; vitamins A, C, D, and E; and grape seed extract were estimated as odds ratios and 95% confidence intervals using conditional logistic regression. Models were adjusted for SCC risk factors and other supplement use.Results
Grape seed extract users had a significantly decreased risk of cutaneous SCC (adjusted odds ratio 0.26, confidence interval 0.08-0.89, P = .031). Multivitamin use was associated with a borderline significant reduction in SCC risk (adjusted odds ratio 0.71, confidence interval 0.51-1.00, P = .049). Use of vitamins A, C, D, and E was not associated with SCC risk.Limitations
The data may be prone to recall and selection bias because of the case-control design. No information was obtained on dose or duration of supplement use.Conclusions
Use of grape seed extract may be associated with a decreased risk of cutaneous SCC. The other supplements included in our study did not reveal clear associations with SCC risk.