Obesity, survival, and chemotherapy outcomes in stage IV colorectal cancer: a retrospective study

Catherine G Tran; Carine Dornbush; Braden S Jensen; Sarah L Mott; Elise E H Fannon; Austin C Stark; Meghan E Mali; Daniel J Berg; Erin E Talbert; Carlos H F Chan

doi:10.1186/s12885-026-15653-8

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Obesity, survival, and chemotherapy outcomes in stage IV colorectal cancer: a retrospective study

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Obesity, survival, and chemotherapy outcomes in stage IV colorectal cancer: a retrospective study

Catherine G Tran, Carine Dornbush, Braden S Jensen, Sarah L Mott, Elise E H Fannon, Austin C Stark, Meghan E Mali, Daniel J Berg, Erin E Talbert and Carlos H F Chan

BMC cancer, Vol.26(1), 331

12/2026

DOI: 10.1186/s12885-026-15653-8

PMCID: PMC12977402

PMID: 41645107

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Abstract

Background Obesity increases risk for colorectal cancer (CRC) development and historically has been connected to poor outcomes. The obesity paradox describes recent data showing that obesity may be protective in some diseases. This study examined the association between obesity and overall survival (OS) in stage IV CRC, evaluating factors that may contribute to disease course. Methods This was a single-institution, retrospective study of patients with stage IV CRC who underwent resection, chemotherapy, and/or radiation. Patients were grouped by body mass index (BMI) at diagnosis, as normal weight (NW), overweight, or obese. Cox regression models were used to estimate the effects of patient, disease, and treatment characteristics on OS. Results 320 patients with stage IV CRC were identified, including 108 NW, 109 overweight, and 103 obese patients. No statistically significant differences were found in age, sex, race, primary tumor site, KRAS/BRAF mutational status, tumor stage, or treatment modality between groups. Obese patients more frequently had higher node-positive disease. Duration of chemotherapy significantly differed by BMI (median duration: NW = 6.5 months, overweight = 6.2, and obese = 11.7, p = 0.04). Chemotherapy adverse event scores and reasons for chemotherapy cessation did not differ by BMI group. On multivariable analysis, NW and overweight patients were at increased risk of death compared to obese patients (NW: HR 1.95, 95% CI 1.39–2.73; overweight: HR 1.43, 95% CI 1.03–1.99). Conclusions Obesity at diagnosis is associated with improved OS in stage IV CRC. Patients with obesity underwent a longer duration of chemotherapy and experienced greater decreases in BMI during this period.

Chemotherapy

Colorectal Cancer

Obesity

Metastatic colorectal cancer

BMI

Details

Title: Subtitle: Obesity, survival, and chemotherapy outcomes in stage IV colorectal cancer: a retrospective study
Creators: Catherine G Tran - University of Iowa
Carine Dornbush - University of Iowa
Braden S Jensen - University of Iowa Health Care
Sarah L Mott - University of Iowa
Elise E H Fannon - University of Iowa Health Care
Austin C Stark - University of Iowa Health Care
Meghan E Mali - University of Iowa Health Care
Daniel J Berg - University of Iowa
Erin E Talbert - University of Iowa
Carlos H F Chan - University of Iowa
Resource Type: Journal article
Publication Details: BMC cancer, Vol.26(1), 331
DOI: 10.1186/s12885-026-15653-8
PMID: 41645107
PMCID: PMC12977402
NLM abbreviation: BMC Cancer
ISSN: 1471-2407
eISSN: 1471-2407
Publisher: Springer Nature; LONDON
Grant note: P30 CA086862 / NCI NIH HHS CA148062 / National Institutes of Health T32
Language: English
Electronic publication date: 02/05/2026
Date published: 12/2026
Academic Unit: Molecular Physiology and Biophysics; Hematology, Oncology, and Blood & Marrow Transplantation; Surgery; Radiation Oncology; Fraternal Order of Eagles Diabetes Research Center; Health, Sport, and Human Physiology ; Internal Medicine
Record Identifier: 9985139277902771

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