Skip Navigation
National Cancer Institute U.S. National Institutes of Health www.cancer.gov
Sections
You are here: Home Community Dialog Questions Submitted Online question_1296837100
Back to Questions

Question ID: WS-36
Submitted by: Barry Graubard
February 4, 2011

While the causal mechanisms that link excess body weight to increased risk for certain cancers are largely unknown (as noted in other questions), we pose an associated question -- what are the causal mechanisms that link excess body weight to decreased risk of certain other cancers? Background: While many studies have documented an increased risk of incidence of certain cancers in association with increased body weight (renal cancer, cancer of the uterus, and esophageal cancer) many studies have documented a reduced risk of other cancers with increased body weight (e.g., lung, pre-menopausal breast, gastric non-cardia adenocarcinoma, and low grade prostate cancer). Of particular note, studies show that greater body weight increases risk of esophageal adenocarcinoma but decreases risk of esophageal squamous cell carcinoma, which suggests that results are not spurious. The biological mechanisms that underlie these associations remain poorly understood. Since body weight is a result of a complex time varying biological process, it is likely body weight is a mediating factor for various causal pathways for cancer. A non-cancer example of likely mediation of obesity is its relation to diabetes. It has been observed that after bariatric surgery and before there is any substantial loss in body weight, glucose levels in the body drop moving diabetics into nondiabetic status. There are many factors related to the accumulation or reduction of body weight including the aging process, early life development and exposures, genetics, levels of basal metabolism, caloric intake, physical activity and fitness, behavioral and psychological disposition, and cultural and ethnic norms. Understanding how these factors affect body weight will provide insight into identifying exposures that cause or prevent certain cancers that have been previously found to be associated with body weight. Feasibility: Existing cohorts with regular repeated measurements of body weight and factors related to the determination of body weight would allow the application of newly developed statistical methods that use time dependent causal modeling to examine exposures related to cancer and the extent that body weight is a mediator of these associations. These analyses could reveal how changes in body weight over time are associated with some cancers and not others. However, many of these cohorts are limited by small sample sizes or have inadequate measurements or lack measurements of the important factors related to body weight. Therefore, new cohorts need to be established that will provide hard measurements of the factors affecting body weight. Other sources of data are randomized intervention trials that use various means to reduce or maintain body weight. These data sources can be used to examine bio-markers of cancer development, which could provide clues about the mediating pathways of the body weight and specific cancers. Implications of success: A deeper understanding of the mediating relationships of stable or changing body weight with cancer could identify those exposures that increase or reduce the incidence of specific cancers. Identification of these exposures can lead to interventions that prevent cancer.

This question has not yet been evaluated by users

Comments

Download Plugins: Download Plugin Adobe Acrobat Reader   Download Plugin Adobe Flash Player   Download Plugin Microsoft Word Viewer   Download Plugin Microsoft Excel Viewer   Download Plugin Microsoft PowerPoint Viewer   Download Plugin Real Player   Download Plugin Windows Media Player   Download Plugin Quicktime Player   Download Plugin WinZip
National Cancer Institute Department of Health and Human Services National Institutes of Health USA.gov