Diabetes, Obesity, & Risk of Pancreatic Cancer

Diabetes Mellitus and Obesity as Risk Factors for Pancreatic Cancer

      Cancer is the second leading cause of death in the United States. About 1/3 of cancer cases are caused by dietary factors. Pancreatic Ductal Adenocarcinoma (PDAC) is the third leading cause of cancer mortality in both men and women, and is only getting worse. Research has found that obesity and type 2 diabetes (T2DM) are both related to PDAC. Although they often coexist, they have found to individually increase risk of PDAC.

      In one study of over 900,000 people, men and women with a BMI >40 were at a significantly increased risk of death from multiple cancers when compared to normal-weight individuals. Although obesity has shown to be a risk factor for many type of cancers, an increased hip-to-waist ratio has shown to increase risk of PDAC by more than 70%. One study found that BMI 30-35 was associated with a 19% increased risk of PDAC development. Studies have shown that weight loss from dietary restriction, increased exercise, or bariatric surgery reduces risk of cancer. 

      There are multiple mechanisms that overlap between obesity and T2DM. These include insulin resistance, hyperinsulinemia (as a result of insulin resistance), and increased insulin-like growth factor (IGF-1). IGF-1 can promote tumor growth. Research has actually found that the significance of insulin and IGF-1 on PDAC comes from the effects of metformin on tumor growth. Metformin lowers insulin and IGF-1 and has been shown to decrease risk of PDAC by actually cancer cell growth. However, these findings were in patients with early stages of PDAC. Metformin did not seem to have any effect on advanced PDAC. 

      Obesity and T2DM have also been classified as systemic inflammatory conditions, which may promote tumor growth. When pancreatic inflammation is targeted using aspirin or targeted blockade of inflammatory cytokines, cancer development/growth seems to be reduced. Weight loss can reduce inflammation which may lead to decreased risk and progression of PDAC. 

      Although dietary factors are difficult to determine based on selection and recall bias, there have been some associations made. When it comes to carbohydrates, One study found that consumption of 2 or more soft drinks per week was linked to an increased risk of PDAC. Another study found that high free fructose intake and/or high free glucose intake were both linked to a significant increased risk of PDAC. However, no associations have been found between glycemic load or glycemic index and PDAC risk. 

    One study found that intake of total fat were associated with increased risk of PDAC, specifically, saturated fat from red meat and dairy. Also, meat cooked at high temperatures was found to increase risk. Another study found that omega 3 polyunsaturated fatty acids were associated with a significantly decreased risk of PDAC. 
      
      No associations have been found between fruit and vegetable intake and PDAC risk. 


      As dietitians, we are on the forefront of obesity and T2DM prevention. Understanding how obesity and T2DM relate to certain cancers can help us reduce risk of all 3 chronic diseases. If we can use diet to reduce obesity, and type 2 diabetes, we may be able to reduce risk of PDAC overall. 


SR


Diabetes Mellitus and Obesity as Risk Factors for Pancreatic Cancer

Eibl, Guido et al.
Journal of the Academy of Nutrition and Dietetics , Volume 118 , Issue 4 , 555 - 567

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