Cohort studyindependent cross-checkfull text checked★ key study I-BAR-118 in-depth review

US study: cancer after weight-loss surgery

Association of Bariatric Surgery With Cancer Risk and Mortality in Adults With Obesity.

Overview

Aminian et al.. JAMA 2022 · PMID 35657620 · DOI 10.1001/jama.2022.9009

Over 10 years, obesity-related cancer occurred in 2.9% after surgery vs 4.9% without; cancer deaths 0.8% vs 1.4%.

Does the study support the specific claim? No · Methodological quality: moderate

Study explained simply

What did the researchers want to find out?: Cancer risk after surgery
How was the study done?: Matched cohort
How many people, animals or samples were studied?: 30,318
What was actually found?: Fewer cancers and cancer deaths
How large was the observed effect?: aHR 0.68 and 0.52
What do the results mean in everyday life?: Surgery was linked to less cancer, not more
What are the study's limitations?: Observational, single system
What does it say about Elawady's specific claim?: Contradicts the claim
Do the results apply to Germany and Europe?: Plausible
What can explicitly not be concluded from this study?: Sleeve-only long-term effect

Authors: Aminian et al.
Journal: JAMA
Year: 2022
Identifier: PMID 35657620 DOI 10.1001/jama.2022.9009
Verification: verified – PubMed efetch 2026-10-26 + Crossref API
Retracted: no
Corrections: none
Extent checked: full text
Conflicts of interest and funding: Several authors report industry fees/grants (e.g. Medtronic, Ethicon, Novo Nordisk) per full text; no separate funding statement located.

Is bariatric surgery associated with lower cancer incidence and cancer mortality in adults with obesity?

Study design: Cohort study – Matched cohort (SPLENDID) with doubly robust estimation, 1:5 matching
Population: Adults BMI >=35 at a US health system (Cleveland Clinic), 2004-2017
Country: USA
Period: 2004-Feb 2021
Sample size: 30,318 (5,053 surgery: RYGB 66%, SG 34%; 25,265 controls)
Inclusion and exclusion criteria: Excluded prior cancer, alcohol use disorder, transplant, HIV and others

Exposure / intervention: RYGB or SG
Comparator: Matched nonsurgical patients
Endpoints: 13 obesity-associated cancers (incl. oesophageal adenocarcinoma); all cancer; cancer mortality
Statistical methods: Propensity matching plus multivariable Cox (doubly robust); E-values

Results: Obesity-associated cancer 3.0 vs 4.6/1000 person-years; 10-y cumulative 2.9% vs 4.9% (ARD 2.0%); aHR 0.68 (0.53-0.87). Cancer mortality 0.6 vs 1.2/1000 PY; 10-y 0.8% vs 1.4% (ARD 0.6%); aHR 0.52 (0.31-0.88). Weight difference at 10 y 19.2%.
Absolute risks: 10-y obesity-associated cancer 2.9% vs 4.9%; cancer death 0.8% vs 1.4%.
Authors' conclusion: Bariatric surgery was associated with significantly lower incidence of obesity-associated cancer and cancer-related mortality.

NNT ~50 over 10 y for obesity-associated cancer, ~167 for cancer death (stats/I-BAR-118_splendid_2022.py); CI log-symmetric.

Directly contradicts "sleeve brings cancer forward": cancer incidence and cancer deaths were lower, in a cohort with one third sleeve.

Sleeve-only results not in abstract.

US data.

Moderate-quality evidence of lower cancer risk after surgery.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	moderate
Risk of bias	some concerns
Precision of results	moderate
Directness	direct
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	moderate
Adequacy of the interpretation (by the archive)	not applicable

Sleeve-specific very long-term cancer risk.