Can weight-loss surgery prevent cancer?

Can weight-loss surgery prevent cancer?

It is clear that significant long-term weight loss achieved through bariatric surgery results in improved health through resolution of diabetes, hypertension, obstructive sleep apnea, reflux disease, depression and a number of other significant comorbidities. 

It has been less clear how weight-loss surgery affects the development of cancer in this patient group.

But a recent U.S. study has demonstrated that gastric bypass surgery may result in lower cancer incidence.

We now have convincing evidence that there is an association between obesity and some cancers, although the cause of the relationship is not yet clear and the results are not yet as strongly supported in the scientific literature as for the other health problems listed above. 

Because there are many types of cancers, each with its own underlying cause, sorting out which cancers occur more frequently in obese patients is difficult. Nevertheless, there appears to be an association between obesity and cancers of the breast, colon, endometrium, esophagus, pancreas and kidneys.

The protective effect of weight loss seems to be most pronounced for female obesity-related tumors, specifically breast and uterine cancers, and is stronger in postmenopausal women. The likely reason is that body fat produces estrogen and estrogen-like hormones, and we know that breast and ovarian cancers can be stimulated to grow by these hormones. With significant weight loss these hormone levels decrease.

A recent nurses’ health study concluded that for overweight women who have never used hormone replacement therapy, losing weight after menopause — and keeping it off — cut their risk of post-menopausal breast cancer in half.

Colorectal cancer represents another specific malignancy that has been linked to obesity and whose risk has been shown to decrease with massive weight loss. Although we do not know why, one partial explanation is that patients undergoing bariatric surgery typically receive a comprehensive presurgical workup that includes screening colonoscopy. 

Surgery patients likely receive more frequent GI follow-up that detects and removes colon polyps before they can develop into full-fledged colon cancer. Other explanations not yet proven include reduction of chronic inflammation of the colon and diversion of bile salts and acids due to surgery.

In conclusion, meaningful durable weight loss improves patients’ life and health in many areas. Whether a patient’s weight loss is through diet and exercise, medication, or surgery, the risk for cancer is decreased. For the majority of morbidly obese patients however, diet, exercise and medications are unsuccessful. Bariatric surgery is the only option that offers effective long-term results and is most likely to help prevent future health problems including some common cancers.

The Weight Loss Surgery Institute of the Central Coast is a multidisciplinary integrated bariatric surgery program that is present at all Dignity hospitals and serves the entire California Central Coast. Based at Marian Regional Medical Center in Santa Maria, our program offers specialist consultation and expert care from dedicated surgeons, nurse coordinator, dietitians and a comprehensive team of specialist physicians skilled and experienced in caring for bariatric patients to help them lose weight safely and effectively. 

With outpatient clinics, monthly educational seminars and full-time dieticians at both French Hospital in San Luis Obispo and Marian Regional Medical Center in Santa Maria, and monthly support groups in Paso Robles and Santa Maria, we offer local high-quality care to serve patients who previously have had to travel to Fresno, Santa Barbara or even farther to get expert, compassionate care.

“Your Cancer Answers” column is produced by Marian Cancer Care Services. Email questions to


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