in a large prospective study published in JAMA Dermatology.
There was also an inverse association between intake of carotenoids and risk of cutaneous SCC over the follow-up period of 26-28 years. The results of the study support “the protective role of vitamin A against SCC development,” wrote Jongwoo Kim, MD, of Brown University, Providence, R.I., and Inje University, Seoul, South Korea, and coauthors. “Our data further support the contention that supplemental and dietary vitamin A may be beneficial in preventing SCC,” they added.
The study evaluated intake of vitamin A and carotenoids and SCC risk with data from the Health Professionals Follow-Up Study (1986-2012) of 48,400 men, and the Nurses’ Health Study (1984-2012) of 75,170 women. Participants in those studies completed questionnaires based on lifestyle and medical history. Only white participants were included, because of the low number of SCC cases and low SCC risk in nonwhite participants, and participants who did not report diet and those who had a history of melanoma, SCC, or other cancer diagnoses at baseline were excluded.
Over the follow-up of 26-28 years, a total of 3,978 SCC cases were confirmed using pathological records. The investigators used different quintiles based on the median total amount of vitamin A intake. Using quintile 1 (lowest intake) as a reference, the pooled multivariate hazard ratios of vitamin A intake were 0.97, 0.97, 0.93, and 0.83 for quintiles 2, 3, 4, and 5, respectively (P less than .001 for the trend, in order of increasing quintiles).
In addition, they reported that greater intakes of retinol and several carotenoids were also significantly associated with a lower SCC risk.
The results were “generally consistent between men and women,” and “the inverse associations appeared to be more prominent among those with moles and those with burn or blistering sunburn reaction as children or adolescents,” they wrote.
The large sample size, prospective design, and confirmation of SCC cases by histology are among the strengths of the study, while a key limitation of the study was the homogeneous nature of the study population, which “may limit the generalizability of our findings,” the authors wrote.
The study was funded by the National Institutes of Health and Inje University (South Korea). One author reported serving as a consultant for AbbVie, Amgen, the Centers for Disease Control and Prevention, Janssen, Merck, Novartis, and Pfizer; and as a compensated investigator for Amgen, Regeneron, and Sanofi. Dr. Kim and the remaining three authors reported no disclosures.
SOURCE: Kim J et al. JAMA Dermatol. 2019 Jul 31. doi: 10.1001/jamadermatol.2019.1937.