Risk of keratinocyte carcinomas with vitamin D and calcium supplementation: a secondary analysis of a randomized clinical trial

• Published in: The American journal of clinical nutrition Vol. 112; no. 6; pp. 1532 - 1539
• Main Authors: Passarelli, Michael N, Karagas, Margaret R, Mott, Leila A, Rees, Judy R, Barry, Elizabeth L, Baron, John A
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2020; Oxford University Press; American Society for Clinical Nutrition, Inc
• Subjects: Adenoma; Aged; Basal cell carcinoma; Calciferol; Calcium; Calcium - administration & dosage; Calcium - pharmacology; Calcium carbonate; Cancer; Carcinoma - classification; Carcinoma - pathology; Carcinoma, Basal Cell - prevention & control; Carcinoma, Squamous Cell - prevention & control; Clinical trials; Colorectal cancer; cutaneous squamous cell carcinoma; Diet; Dietary Supplements; Female; Humans; Invasiveness; keratinocyte carcinomas; Male; Middle Aged; nonmelanoma skin cancer; Original Research Communications; Prevention; Risk; Risk Factors; Risk reduction; Secondary analysis; Skin cancer; Squamous cell carcinoma; Vitamin D; Vitamin D - administration & dosage; Vitamin D - pharmacology; Vitamin D3; calcium; BCC; PTH; vitamin D; PTHrP; UVR; SCC; nonmelanoma skin cancer; KC; 25(OH)D; basal cell carcinoma; WHI; cutaneous squamous cell carcinoma; keratinocyte carcinomas
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/nqaa267

It is unknown whether dietary supplementation with vitamin D or calcium prevents keratinocyte carcinomas, also known as nonmelanoma skin cancers.
This study aimed to determine whether daily vitamin D or calcium supplementation alters the risk of basal cell carcinoma (BCC) or invasive cutaneous squamous cell carcinoma (SCC).
The Vitamin D/Calcium Polyp Prevention Study is 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. During 2004–2008, a total of 2259 men and women, 45–75 y of age, recently diagnosed with a colorectal adenoma, 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.
During a median follow-up of 8 y, 200 (9%) 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; 95% CI: 0.73, 1.26), calcium compared with no calcium (HR: 1.01; 95% CI: 0.74, 1.39), and both agents compared with neither (HR: 0.99; 95% CI: 0.65, 1.51). SCC incidence was unrelated to treatment with vitamin D compared with no vitamin D (HR: 0.79; 95% CI: 0.49, 1.27), but there was suggestive evidence of beneficial treatment effects for calcium compared with no calcium (HR: 0.60; 95% CI: 0.36, 1.01) and both agents compared with neither (HR: 0.42; 95% CI: 0.19, 0.91).
Calcium alone or in combination with vitamin D may reduce the risk of SCC, but not BCC. This trial was registered at clinicaltrials.gov as NCT00153816.