Diet and Skin Cancer: The Potential Role of Dietary Antioxidants in Nonmelanoma Skin Cancer Prevention

Table 1

Experimental studies of AO supplements and NMSC incidence in human subjects.

Study	Study design	Antioxidant and other supplements studied	Effect on NMSC risk	Statistically significant results	Study location
Frieling et al., 2000 [35]	RCT of 22,071 male physicians over 12 years	50 mg beta-carotene, QOD	None	NA	USA
Duffield-Lillico et al., 2003 [36]	RCT of 1312 patients with previous NMSC over 10 years	200 mcg selenium, QD	BCC: none; SCC: increased risk	BCC: NA; SCC: RR: 1.14; 95% CI, 0.93–1.39	USA
Reid et al., 2008 [37]	RCT of 424 adults followed for 6 years, and a subset of 315 adults in the NPC study [37]	200 mcg selenium NPC subset, QD	NMSC: increased risk	200 mcg cohort: RR: 1.49; 95% CI: 1.10–2.03; : 0.008	USA
		400 mcg selenium, QD	None	NA
Greenberg et al., 1990 [38]	RCT of 1805 patients with history of NMSC over 5 years	50 mg beta-carotene, QD	None	RR: 1.05; 95% CI, 0.91–1.22	USA
Hercberg et al., 2007 [39]	RCT of 13,017 adults followed over median of 7.5 years	Daily combination of: 120 mg vitamin C; 30 mg vitamin E; 6 mg beta-carotene; 100 mcg selenium; 20 mg zinc	BCC: none; SCC: increased risk in women	BCC: NA; SCC: Women: aHR: 1.68; : 0.03	France
Vinceti et al., 2014 [40]	Meta-analysis which included 3 RCTs of NMSC	Selenium^+	NMSC: increased risk	RR: 1.44; 95% CI: 0.95–1.17	Asia, Europe, US, and Australia
Chang et al., 2011 [41]	Meta-analysis of 10 RCTs	Vitamin A^+; Vitamin C^+; Vitamin E^+; B-carotene^+	None	NA	USA, Netherlands, Australia, UK, and Canada

Dosages varied. aHR: adjusted hazard ratio; BCC: basal cell carcinoma; CI: confidence interval; NA: not applicable; NMSC: nonmelanoma skin cancer; mg: milligrams; mcg: micrograms; QD: daily dosing; QOD: every other day dosing; : value; RCT: randomized control trial. RR: relative rate; SCC: squamous cell carcinoma.