To Örebro University

Objective: Our objective was to evaluate how the incidence of cancer after metabolic and bariatric surgery (MBS) compared with the general population.

Methods: A nationwide cohort of patients who underwent MBS in Sweden from 2007 to 2020 were matched (age, sex, area of residence) to controls from the general population. All patients were followed for new incidence of cancer.

Results: Among the 68,424 patients who underwent MBS compared with the 640,944 controls, there was no difference in the risk for new onset of cancer (incidence rate ratio [IRR]: 1.03, 95% CI: 0.99-1.07). Compared with controls, MBS was associated with a lower risk for breast cancer in women (IRR: 0.78, 95% CI: 0.71-0.86) and nonmelanoma (IRR: 0.71, 95% CI: 0.59-0.85) and melanoma (IRR: 0.77, 95% CI: 0.68-0.87) skin cancer in men and women, but an increased risk remained for colon cancer, liver cancer, pancreatic cancer, corpus uteri cancer, renal cancer, malignant meningioma, and non-Hodgkin's lymphoma.

Conclusions: All-cancer incidence risk was similar between patients who underwent MBS and the general population. Although breast and skin cancer risk was lower among MBS patients compared with controls, MBS patients had a greater risk for multiple cancer types. Thus, patients who have undergone MBS should continue recommended cancer screening and clinically approved work-up for cancer symptoms as recommended for the general population.