Annual ambient UVB at wavelengths that induce Vitamin D synthesis is associated with reduced oesophageal and gastric cancer risk: a nested case-control study

Vitamin D has been shown to be beneficial at reducing the risk of cancer, however studies examining oesophageal and gastric cancer have been scarce and findings inconsistent. The UK Biobank cohort was used for this nested case-control study (N=3,732). Primary, incident oesophageal and gastric cancer cases diagnosed after recruitment were identified via linkage to National Cancer Registries. Tropospheric emissions monitoring internet service database was used to calculate ambient annual UVB dose (D-UVB). Conditional logistic regression was used to investigate the relationship between annual ambient D-UVB and risk of oesophageal and gastric cancer and odds ratios (OR) are reported. In total, 373 oesophageal and 249 gastric cancer cases and 3,110 age- and gender-matched controls were included in the study. We found a strong inverse association between annual ambient UVB and odds of developing oesophageal or gastric cancer: compared to the lowest tertile, OR for the highest tertile was 0.64 (95%CI: 0.51-0.79) in adjusted analysis. The association was strengthened when restricted to oesophageal cancer (OR = 0.60; 95%CI: 0.45-0.80), and oesophageal adenocarcinoma cases (OR = 0.48; 95%CI: 0.34-0.68). Similar results were found in unadjusted and stratified analysis. In conclusion, ambient UVB radiation is inversely associated with the development of oesophageal and gastric cancer, even in a high latitude country.