Takeaway
- Obesity surgery (OS) was not associated with increased colorectal cancer (CRC) risk, except in patients aged ≥50 years at the time of surgery.
- Post-OS, breast cancer (BCa) risk was reduced but endometrial and kidney cancer risk remained elevated.
Why this matters
- There is evidence that OS may increase CRC risk despite weight loss, but other studies have found reduced risk after OS.
- Most previous studies are limited by sample size and follow-up.
Key results
- Overall, standardised incidence ratio (SIR) for CRC in the surgery cohort was not significantly increased compared with the background English population (SIR, 1.26; 95% CI, 0.92-1.71) but was increased in patients ≥50 years old at surgery (SIR, 1.47; 95% CI, 1.02-2.06).
- Slightly increased CRC risk was seen in no-surgery patients (SIR, 1.12; 95% CI, 1.08-1.16) vs background population; risk was higher in males (SIR, 1.21; 95% CI, 1.15-1.26) than females (SIR, 1.02; 95% CI, 0.97-1.08).
- There was a decreased risk for BCa after OS (SIR, 0.76; 95% CI, 0.62-0.92).
- BCa risk was slightly increased in the no-surgery group (SIR, 1.08; 95% CI, 1.04-1.11).
- Risk for endometrial cancer was increased in the surgery (SIR, 2.98; 95% CI, 2.25-3.90) and no-surgery (SIR, 2.60; 95% CI, 2.48-2.73) groups vs background population.
- Renal cancer risk was increased in both the groups (SIRs, 3.06 [95% CI, 2.08-4.34] and 1.78 [95% CI, 1.68-1.89], respectively).
- Lung cancer risk was reduced in the OS group (SIR, 0.70; 95% CI, 0.46-1.03) and was slightly raised in no-surgery patients (SIR, 1.09; 95% CI, 1.05-1.13).
Study design
- Retrospective observational study of obese adults who underwent OS (surgery cohort) or not (no-surgery cohort) during 1997-2013.
- Funding: World Cancer Research Fund; Cancer Research UK.
Limitations
- No-surgery cohort limited to patients with obesity-related hospitalisation, outpatient or accident and emergency attendance.
- No data on BMI and other CRC risk factors.
References
References