The obesity paradox in patients with colorectal cancer: a systematic review and meta-analysis.

Yiding Li, Chenhan Li, Guiling Wu, Wanli Yang, Xiaoqian Wang, Lili Duan, Liaoran Niu, Junfeng Chen, Yujie Zhang, Wei Zhou, Jinqiang Liu, Liu Hong, Daiming Fan

Journal: Nutrition reviews 2022;80(7):1755-1768

PMID: 35182150

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Abstract

CONTEXT

Obesity is widely regarded as an established risk factor for colorectal cancer (CRC). However, recent studies have shown that lower mortality and better cancer-specific survival were observed in CRC patients with elevated body mass index (BMI), an example of the obesity paradox, which is the inverse correlation between obesity and mortality in some populations.

OBJECTIVE

The aim of this systematic review and meta-analysis was to investigate the association between BMI and CRC outcomes.

DATA SOURCES

PubMed, Web of Science, MEDLINE, the Cochrane Library, and Embase databases were searched for relevant articles published from inception to December 31, 2020.

STUDY SELECTION

Studies comparing the prognosis of CRC patients with obesity or overweight with that of normal-weight CRC patients were eligible.

DATA EXTRACTION

Data were extracted by 2 reviewers independently; differences were resolved by a third reviewer. BMI was classified according to WHO categories.

DATA ANALYSIS

To assess the prognostic effects of different BMI categories in CRC patients, hazard ratios and 95%CIs of overall survival, disease-free survival, and cancer-specific survival were extracted from included articles.

RESULTS

Sixteen studies (55 391 patients in total) were included. Higher BMI was significantly associated with more favorable CRC outcomes. Compared with normal-weight patients, underweight patients had worse overall survival (HR = 1.26; 95%CI, 1.15-1.37) and disease-free survival (HR = 1.19; 95%CI, 1.11-1.27, while patients with overweight had better overall survival (HR = 0.92; 95%CI, 0.86-0.99), disease-free survival (HR = 0.96; 95%CI, 0.93-1.00), and cancer-specific survival (HR = 0.86; 95%CI, 0.76-0.98). Patients with morbid obesity had worse overall survival (HR = 1.12; 95%CI, 1.02-1.22) and disease-free survival (HR = 1.15; 95%CI, 1.07-1.24) than normal-weight patients. There was no significant difference in cancer-specific survival between patients with obesity (HR = 0.94; 95%CI, 0.76-1.16) and patients with normal weight, nor between patients with underweight and patients with normal weight (HR = 1.14; 95%CI, 0.82-1.58).

CONCLUSIONS

CRC patients with a higher BMI appear to have reduced mortality compared with normal-weight CRC patients, even though higher BMI/obesity is an established determinant for the development of CRC.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020202320.

Address: the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; College of Life Science, Northwest University, Xi'an, Shaanxi Province, China.; Key Laboratory of Ministry of Education, School of Aerospace Medicine, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases , Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province , China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an , Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University , Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases , Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.; the State Key Laboratory of Cancer Biology and National Clinical Research Center for Digestive Diseases, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi Province, China.

DOI: 10.1093/nutrit/nuac005

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MeSH Terms: Body Mass Index, Colorectal Neoplasms, Humans, Obesity, Overweight, Thinness