Association between weight loss and serum biomarkers with risk of incident cancer in the Longitudinal Assessment of Bariatric Surgery cohort.

BACKGROUND

Bariatric surgery reduces cancer risk in populations with obesity. It is unclear if weight loss alone or metabolic changes related to bariatric surgery cause this effect.

OBJECTIVE

We evaluated the relationship between surgical weight loss and serum biomarker changes with incident cancer in a bariatric surgery cohort.

SETTING

Ten U.S. clinical facilities.

METHODS

The Longitudinal Assessment of Bariatric Surgery 2 (LABS-2) is a prospective multicenter cohort (n = 2458, 79% female, mean age = 46). We evaluated weight and serum biomarkers, measured preoperatively and 1 year postoperatively, as predictors for incident cancer. Associations were determined using Cox proportional hazards models adjusting for weight loss, age, sex, education, and smoking history.

RESULTS

Over 8759 person-years of follow-up, 82 patients reported new cancer diagnosis (936 per 100,000 person-years, 95% confidence interval [CI]: 749-1156). Cancer risk was decreased by approximately 50% in participants with 20% to 34.9% total weight loss (TWL) compared with <20% TWL (hazard ratio [HR] = .49, 95%CI: .29-.83). Reduced cancer risk was observed with percent decrease from baseline for glucose (per 10%, HR = .94, 95%CI: .90-.99), proinsulin (per 20%, HR = .95, 95%CI: .93-.98), insulin (per 30%, HR = .97, 95%CI: .96-.99), and leptin (per 20%, HR = .81, 95%CI: .68-.97), and per 15% percent increase in ghrelin (HR = .94, 95%CI: .29-.83).

CONCLUSIONS

After bariatric surgery, cancer risk is reduced >50% when weight loss exceeds 20% TWL compared with patients with <20% TWL. Weight loss alone may not explain the observed risk reduction, as improvements in diabetes, leptin, and ghrelin were associated with decreased cancer risk.