Incidence of polyp formation following bariatric surgery

Multiple studies have linked obesity to an increased risk of cancer. The correlation is so strong that the national cancer prevention guidelines recommend weight loss for patients with obesity to reduce their risk of cancer. Bariatric surgery has been shown to be very effective in sustained weight loss. However, there have been mixed findings about bariatric surgery and its effects on the risk of colorectal cancer.

This study sought to examine bariatric surgery patients and their risk of pre-cancerous or cancerous polyps to elucidate any risk factors or associations between bariatric surgery and colorectal cancer.

A retrospective review of the academic medical center's bariatric surgery database was performed from January 2010 to January 2017. Patients who underwent medical or surgical weight loss and had a subsequent colonoscopy were included in the study. Positive colonoscopy findings were described as malignant or premalignant polyps.

A total of 1777 patients were included, with 1360 in the medical group and 417 in the surgical group. Data analysis included patient demographics, co-morbidities, procedure performed, surgical approach, weight loss, and colonoscopy findings. A multivariate analysis was used to determine whether an association exists between weight loss and incidence of colorectal polyps, and if so, whether the association different for medical versus surgical weight loss.

A higher percentage of body mass index (BMI) reduction was seen in the surgical group. An overall comparison showed average reductions in BMI of 27.7% in the surgical group and 3.5% in the medical group (P < .0001). Patients with the greatest reduction in BMI, regardless of medical or surgical therapy, showed a lower incidence of precancerous and cancerous polyps (P = .041).

This study offers a unique approach in examining the incidence of colorectal polyps related to obesity. Patients with the greatest reduction in their BMI, more common in the surgical group, had a lower incidence of precancerous and cancerous polyps.