May C Tee, MD, MPH, Yin Cao, MPH, Garth L Warnock, MD, MSc, Frank B Hu, MD, PhD, Jorge E Chavarro, MD, ScD
Harvard School of Public Health, University of British Columbia
Obesity is a major public health issue and is associated with increased risk of several cancers, currently a leading cause of mortality. Obese patients undergoing bariatric surgery may allow for evaluation of the effect of intentional excess weight loss on subsequent risk of cancer. We aim to evaluate cancer risk, incidence, and mortality following bariatric surgery.
A comprehensive literature search was conducted using PubMed / MEDLINE and Embase from the inception of both databases to January 2012. Inclusion criteria incorporated all human studies examining oncologic outcomes following bariatric surgery. Two authors independently reviewed selected studies and relevant articles from their bibliographies for data extraction, quality appraisal, and meta-analysis.
Six observational studies (N = 51,740) comparing relative risk (RR) of cancer in obese patients undergoing bariatric surgery versus obese controls were analyzed. Overall, the RR of cancer in obese patients after undergoing bariatric surgery is 0.55 [95% CI: 0.41-0.73, P < 0.0001, I2 = 83%]. The effect of bariatric surgery on cancer risk is modified by gender (P = 0.021). When stratified by gender, the pooled RR in females is 0.68 [95% CI: 0.60-0.77, P < 0.0001, I2 < 0.1%] while in males is 0.99 [95% CI: 0.74-1.32, P = 0.937, I2 < 0.1%].
Our results suggest that bariatric surgery reduces cancer risk and mortality in formerly obese patients. When stratifying our meta-analysis by gender, the effect of bariatric surgery on oncologic outcomes is protective in women but not in men.
Program Number: P007