Calcium, Vitamin D, Dairy Products, and Mortality Among Colorectal Cancer Survivors The Cancer Prevention Study-II Nutrition Cohort

SUMMARY: The American Cancer Society estimates that approximately 137,000 new cases of colorectal cancer will be diagnosed in the United States in 2014 and over 50,000 are expected to die of the disease. Data from 60 epidemiological studies enrolling more than 26,000 ColoRectal Cancer (CRC) patients have shown that higher consumption of milk and dairy products reduces the risk of colon cancer and high Calcium intake reduces the risk of CRC. In vivo and in vitro studies have confirmed these findings. Milk, in addition to being a rich source of dietary Calcium and Vitamin D is a primary dietary source of conjugated linoleic acid which has been shown to inhibit colon cancer cell growth. Dairy products also provide other beneficial components such as butyric acid, lactoferrin and fermentation products. The impact of milk and dairy products on CRC survival however has remained unclear. The Cancer Prevention Study – II Nutrition Cohort is a prospective study of cancer incidence that began in 1992. Participants in this study (N=184,000) were provided a self administered questionnaire and baseline information about their dietary habits (including dietary Calcium and Vitamin D, as well as Calcium, Vitamin D and multivitamin supplements), physical activity, body size, cancer screening and early detection, etc. was collected and follow up questionnaires were sent every other year to update information and learn about new cancer diagnosis. Patients were followed up until June 2009 and by the end of this period, 3,832 individuals who had no history of disease at baseline had been diagnosed with invasive colon or rectal cancer. After excluding patients with distant metastatic disease, 2,284 patients were included in this analysis and among them, 1,111 patients reported post diagnosis diet. The primary outcome of this study was all cause mortality and the secondary outcome was mortality resulting from colorectal cancer. Using standard statistical models, the investigators noted that post CRC diagnosis total Calcium intake and milk intake, was inversely associated with all-cause mortality and significantly reduced CRC specific mortality. This benefit however, was not seen with Vitamin D intake. Also of interest, pre-diagnosis Calcium, Vitamin D, and dairy product intakes did not influence mortality outcomes. The authors concluded that higher post-diagnosis intakes of total Calcium and milk may be associated with lower risk of death among patients with non-metastatic ColoRectal Cancer. In a more recent publication, it has been reported that there is a strong association between plasma level of 25-hydroxyvitamin D (25-OHD) and CRC specific mortality, with better outcomes in patients with Stage I-III CRC, who had higher plasma levels of 25-OHD (Zgaga L, et al. J Clin Oncol 2014;32:2430-2439). With 30-35% of the malignancies attributed to dietary habits, the onus is therefore on the treating physicians to provide nutrition counseling during and after cancer treatment and is not to be ignored. Yang B, McCullough ML, Gapstur SM, et al. J Clin Oncol 2014;32:2335-2343