Calcium intake and survival after colorectal cancer diagnosis

Purpose: Although evidence suggests an inverse association between calcium intake and colorectal cancer incidence, the influence of calcium on survival after colorectal cancer diagnosis remains unclear. Experimental Design: We prospectively assessed the association of postdiagnostic calcium intake with colorectal cancer–specific and overall mortality among 1,660 nonmetastatic colorectal cancer patients within the Nurses' Health Study and the Health Professionals Follow-up Study. Patients completed a validated food frequency questionnaire between 6 months and 4 years after diagnosis and were followed up for death. Multivariable hazard ratios (HRs) and 95% confidence intervals (95% CI) were calculated using Cox proportional hazards regression. Results: Comparing the highest with the lowest quartile intake of postdiagnostic total calcium, the multivariable HRs were 0.56 (95% CI, 0.32–0.96; P _trend ¼ 0.04) for colorectal cancer–specific mortality and 0.80 (95% CI, 0.59–1.09; P _trend ¼ 0.11) for all-cause mortality. Postdiagnostic supplemental calcium intake was also inversely associated with colorectal cancer–specific mortality (HR, 0.67; 95% CI, 0.42–1.06; P _trend ¼ 0.047) and all-cause mortality (HR, 0.71; 95% CI, 0.54–0.94; P _trend ¼ 0.008), although these inverse associations were primarily observed in women. In addition, calcium from diet or dairy sources was associated with lower risk in men. Conclusions: Higher calcium intake after the diagnosis may be associated with a lower risk of death among patients with colorectal cancer. If confirmed, these findings may provide support for the nutritional recommendations of maintaining sufficient calcium intake among colorectal cancer survivors.