Vitamin D3 Intake Dose and Common Cancer: A Population-Based Case Control Study in a Chinese Population

Objectives: Epidemiological studies suggest that vitamin D status is associated inversely with risk of common cancers in western populations. This study aimed to investigate whether vitamin D is associated with risk of common cancers in Chinese population. Methods: A population-based retrospective case-control study was conducted analyzing data retrieved from the Catastrophic Illness Patient Databases (CIPD) and longitudinal health insurance database (LHID) from January 1, 2010 to December 31, 2011and January 1, 2000 to December 31, 2011, respectively. Cases were identified as subjects diagnosed with site-specific cancers (International Classification of Diseases, Ninth Revision,) and frequency matched to select controls. Use of vitamin D3 was compared between two groups. Odds ratios (ORs) were employed to quantify the risk associated with exposure to vitamin D3 by logistic regression. Results: There were 1.21% (1961/161806) patients in cases and 0.67 % (1092/161806) patients in controls identified were vitamin D3 users. Overall risk of cancers associated with vitamin D3 users was 1.67 (95% CI:1.55 -1.81). Among these, the risk of kidney cancer and bladder cancer associated with intakes of vitamin D3 were significant (OR 2.59; 95% CI 1.81-3.70; OR 4.97; 95% CI 4.40-5.60) in an adjusted model. In further stratification analysis, we found a statistically significant risk of bladder cancer associated with high intake of vitamin D3. Except this, no statistically significant risk of other site-specific cancers associated with high intake of vitamin D3. Conclusion: Except bladder cancer in stratification analysis, we observed no statistically significant association between high intake of vitamin D3 and other site-specific cancers.