Intake of Calcium, Magnesium, and Phosphorus and Risk of Pancreatic Cancer in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

Abstract

Objective Few epidemiological studies have investigated the associations between calcium, magnesium, and phosphorus intake and pancreatic cancer. We examined these associations in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Methods Diet was assessed using the Dietary Questionnaire (DQX) at baseline in the intervention arm and the Dietary History Questionnaire (DHQ) in 1999 or around the third anniversary of randomization in both the intervention and control arms. During a median follow-up of 12.2 years, 279 cases of pancreatic cancer occurred from 58,477 participants who completed DQX; 380 cases arose from 101,622 participants who responded to DHQ over a median follow-up of 8.9 years. Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Results Total calcium intake was inversely associated with pancreatic cancer [HR (95% CI) for the fourth vs. the first quartiles in the DHQ cohort: 0.67 (0.47, 0.96); p-trend: 0.035]. An inverse association was also observed for total magnesium intake [HR (95% CI) for the fourth vs. the first quartiles in the DQX cohort: 0.61 (0.37, 1.00); p-trend: 0.023]. Reduced risk associated with total calcium intake was confined to subjects with a high fat intake (>73 g/day) in the DHQ cohort (p-interaction: 0.16). Conclusions There was not a significant association between dietary phosphorus intake and pancreatic cancer risk in both cohorts. Total intake of calcium and magnesium are associated with a lower pancreatic cancer risk. The effect of total calcium intake was modified by fat intake.