USA: Dietary supplementation with calcium alone or in combination with vitamin D reduces the risk of invasive cutaneous squamous cell carcinoma (SCC) but not basal cell carcinoma (BCC), suggests a recent study in the American Journal of Clinical Nutrition.
It is not known whether dietary supplementation with calcium or vitamin D helps in the prevention of keratinocyte carcinomas, also known as nonmelanoma skin cancers. Michael N Passarelli, Geisel School of Medicine at Dartmouth, Hanover, NH, USA, and colleagues aimed to determine whether daily vitamin D or calcium supplementation alters the risk of BCC or invasive SCC.
For the purpose, the researchers conducted the Vitamin D/Calcium Polyp Prevention Study -- a completed multicenter, double-blind, placebo-controlled, partial 2 × 2 factorial, randomized clinical trial of vitamin D, calcium, or both for the prevention of colorectal adenomas. The study included a total of 2259 men and women (45-75 years of age) who were recently diagnosed with colorectal adenoma. They were randomly assigned to 1000 IU/d of vitamin D3 or placebo and 1200 mg/d of calcium carbonate or placebo for 3 or 5 y, and followed after treatment ended. Reports of incident BCC or SCC were confirmed from pathology records.
Key findings of the study include:
During a median follow-up of 8 y, 9% of the participants were diagnosed with BCC and 68 (3%) participants were diagnosed with SCC.
BCC incidence was unrelated to treatment with vitamin D compared with no vitamin D (HR: 0.96), calcium compared with no calcium (HR: 1.01), and both agents compared with neither (HR: 0.99).
SCC incidence was unrelated to treatment with vitamin D compared with no vitamin D (HR: 0.79), but there was suggestive evidence of beneficial treatment effects for calcium compared with no calcium (HR: 0.60) and both agents compared with neither (HR: 0.42).
"Calcium alone or in combination with vitamin D may reduce the risk of SCC, but not BCC," concluded the authors.
The study, "Risk of keratinocyte carcinomas with vitamin D and calcium supplementation: a secondary analysis of a randomized clinical trial," is published in the American Journal of Clinical Nutrition.
DOI:https://academic.oup.com/ajcn/advance-article-