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Calcium Intake and Survival after Colorectal Cancer Diagnosis.
Yang, W, Ma, Y, Smith-Warner, S, Song, M, Wu, K, Wang, M, Chan, AT, Ogino, S, Fuchs, CS, Poylin, V, et al
Clinical cancer research : an official journal of the American Association for Cancer Research. 2019;(6):1980-1988
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Abstract
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 = 0.04) for colorectal cancer-specific mortality and 0.80 (95% CI, 0.59-1.09; P trend = 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 = 0.047) and all-cause mortality (HR, 0.71; 95% CI, 0.54-0.94; P trend = 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.
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Calcium as a chemopreventive agent against colorectal neoplasm: does obesity play a role?
Keum, N, Kim, H, Giovannucci, EL
Cancer causes & control : CCC. 2017;(8):853-856
Abstract
BACKGROUND Concerning the chemopreventive potential of calcium against colorectal neoplasms, strong evidence from initial randomized controlled trials (RCTs) of colorectal adenoma has not been confirmed from the most recent large RCT. To explain the conflicting results, a new hypothesis was proposed that the benefit of calcium may be confined to lean individuals. METHODS To test this hypothesis, we examined heterogeneity of the associations of calcium intake with adenoma and CRC, using data from the most recent meta-analyses of observational studies and conducting subgroup analysis by average body mass index (BMI) of study population. RESULTS An inverse association of calcium intake with adenoma and CRC did not vary by population average BMI. By anatomical subsites of CRC, while there was no significant evidence of heterogeneity by population average BMI (P heterogeneity > 0.05), the benefit of calcium was confined to studies with population average BMI of ≥25 kg/m2 for both colon cancer and rectal cancer, contradicting the hypothesis. CONCLUSIONS In our study-level meta-analysis, we found no evidence to support that the chemopreventive potential of calcium, if real, may be stronger in leaner individuals.