Abstract 638: Association between calcium intake and pancreatic cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO)

Abstract

Abstract Pancreatic cancer is a leading cause of cancer death in the U.S. and its etiology remains largely unclear. As most patients are diagnosed with an advanced, unresectable disease, primary prevention remains a priority for reducing its incidence and mortality. Although ecological, migrant, and temporal trend studies have shown that diet plays a role in the occurrence of pancreatic cancer, few nutrients that alter its risk have been identified from epidemiologic studies. The present study thus sought to investigate intakes of calcium and fat, adiposity, and their potential interactions in relation to pancreatic cancer risk among participants in the PLCO trial. Usual dietary intake among the participants was assessed with Dietary Questionnaire (DQX) at baseline and Dietary History Questionnaire (DHQ) around their third anniversary of randomization. Of 58,477 participants who completed the DQX, 279 cases of pancreatic cancer were documented during a median follow-up of 12.2 years. A total of 101,721 participants responded to the DHQ and gave risk to 380 cases of pancreatic cancer during a median follow-up of 8.9 years. Cox proportional hazards regression was performed to estimate hazard ratios (HR) and 95% Confidence intervals (CI) for pancreatic cancer in relation to total and dietary intake of calcium, intake of fat, and body mass index (BMI). After adjustment for established and suspected confounders, there was a suggestive inverse association between total calcium intake assessed from both food frequency questionnaires and risk of pancreatic cancer [HR (95% CI) for quartile (Q) 2, Q3, and Q 4 vs. Q1: 0.93 (0.67, 1.30), 0.86 (0.60, 1.24), and 0.71 (0.46,1.09); p-trend, 0.11) for DQX and 0.96 (0.72, 1.26), 0.99 (0.74, 1.33), and 0.72 (0.52, 1.01); p-trend, 0.08) for DHQ]. Overall, this inverse association was stronger or its linear trend in reduced risk across the quartiles of total calcium intake was more apparent among overweight participants (BMI: >25-<30) [e.g. HR (95% CI) for Q2, Q3, and Q4 vs. Q1: 0.91 (0.60,1.38), 0.84 (0.54, 1.30), and 0.72 (0.44, 1.18); p-trend, 0.07) for DHQ]. Among the participants with the highest fat intake (Q4) derived from the DHQ, those with the highest intake of total calcium (Q4) experienced a 65% reduced risk of pancreatic cancer compared with those with the lowest intake (Q1) [HR (95% CI): 0.35 (0.17, 0.68)]. However, the possibility of chance finding for this significant risk reduction could not be ruled out due to multiple comparisons. In addition, no appreciable associations of calcium intake from both dietary and supplemental sources with pancreatic cancer risk was observed. In summary, the present study offers suggestive evidence that total calcium intake was associated with a reduced risk of pancreatic cancer and that this potential benefit may be more pronounced among overweight subjects. Citation Format: Maggie Hoyt, Jianjun Zhang. Association between calcium intake and pancreatic cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 638.