Many studies have also evaluated the effect of obesity on outcomes after cancer diagnosis or treatment. Most studies suggest that being overweight or carrying excess weight increases the risk of mortality after a cancer diagnosis.
For example, obesity at diagnosis of pediatric acute leukemia was significantly associated with an increased risk of mortality, including acute lymphoblastic leukemia (relative risk [RR], 1.31; 95% CI, 1.09-1.58) and acute myeloid leukemia (RR, 1.56; 95% CI, 1.32-1.86).21 Obesity was similarly associated with an increased risk of mortality among patients diagnosed with pancreatic, ovarian, and digestive tract cancers.21-23
Bladder cancer recurrence was associated with obesity (HR, 1.76; 95% CI, 1.36-2.28), but not overall survival.24 Biochemical recurrence of prostate cancer, however, was not consistently associated with obesity.25-26 Overall survival, breast cancer–specific mortality, and disease-free survival were not associated with obesity in studies of breast cancer, including triple-negative disease.27,28
Although lung cancer risk may be associated with obesity, a paradox has been demonstrated consistently with lung cancer outcomes. Being overweight or being obese appears to be protective against morbidity and mortality among patients with lung cancer. A meta-analysis of 14 observational studies including more than 3 million participants found that lung cancer–related mortality was significantly lower in patients who were overweight (HR, 0.84; 95% CI, 0.79-0.90) or obese (HR, 0.81; 95% CI, 0.75-0.87) with moderate heterogeneity compared with those who had a normal BMI.29 Consistent with this, another meta-analysis of 15 prospective cohort studies found a dose-response relationship; for every 5 kg/m2 increase in BMI, there was a 6% decrease in the risk of lung cancer–related mortality (RR, 0.94; 95% CI, 0.92-0.96).30 In addition, in an analysis of 25 observational studies with more than 78,000 participants who underwent lung cancer resection, long-term survival rates were higher in those patients with a higher BMI (odds ratio [OR], 0.69; 95% CI, 0.56-0.86), as well as overall morbidity (OR, 0.84; 95% CI, 0.73-0.98) and in-hospital mortality (OR, 0.78; 95% CI, 0.63-0.98).31
Meta-analyses of primarily cohort studies suggest that obesity is linked to an increase in the risk of developing most cancer types. In some cases, this association may only be relevant to adiposity, also known as abdominal obesity.
The effect of obesity on cancer outcomes, such as mortality, is similar for many cancer types, but there is an apparent paradox for lung cancer. Lung cancer–related mortality and survival after lung resection is improved among patients with obesity.
- Allott EH, Hursting SD. Obesity and cancer: mechanistic insights from transdisciplinary studies. Endocr Relat Cancer. 2015;22(6):R365-R386.
- Arnold M, Freisling H, Stolzenberg-Solomon R, et al. Overweight duration in older adults and cancer risk: a study of cohorts in Europe and the United States. Eur J Epidemiol. 2016;31(9):893-904.
- Lauby-Secretan B, Scoccianti C, Loomis D, et al. Body fatness and cancer — viewpoint of the IARC Working Group. N Engl J Med. 2016;375:794-798.
- Berger NA. Obesity and cancer pathogenesis. Ann N Y Acad Sci. 2014;1311:57-76.
- Freisling H, Arnold M, Soerjomataram I, et al. Comparison of general obesity and measures of body fat distribution in older adults in relation to cancer risk: meta-analysis of individual participant data of seven prospective cohorts in Europe. Br J Cancer. 2017;116(11):1486-1497.
- Du X, Hidayat K, Shi B-M. Abdominal obesity and gastroesophageal cancer risk: systematic review and meta-analysis of prospective studies. Biosci Rep. 2017;37(3):BSR20160474.
- Lin X-J, Wang C-P, Liu X-D, et al. Body mass index and risk of gastric cancer: a meta-analysis. Jpn J Clin Oncol. 2014;44(9):783-791.
- Campbell PT, Newton CC, Kitahara CM, et al. Body size indicators and risk of gallbladder cancer: pooled analysis of individual-level data from 19 prospective cohort studies. Cancer Epidemiol Biomarkers Prev. 2017;26(4):597-606.
- Carreras-Torres R, Johansson M, Gaborieau V, et al. The role of obesity, type 2 diabetes, and metabolic factors in pancreatic cancer: a Mendelian randomization study. J Natl Cancer Inst. 2017;109(9):djx012.
- Dong Y, Zhou J, Zhu Y, et al. Abdominal obesity and colorectal cancer risk: systematic review and meta-analysis of prospective studies. Biosci Rep. 2017;37(6):BSR20170945.
- Jarvis D, Mitchell JS, Law PJ, et al. Mendelian randomisation analysis strongly implicates adiposity with risk of developing colorectal cancer. Br J Cancer. 2016;115:266-272.
- Chen GC, Chen SJ, Zhang R, et al. Central obesity and risks of pre- and postmenopausal breast cancer: a dose-response meta-analysis of prospective studies. Obes Rev. 2016;17(11):1167-1177.
- Jenabi E, Poorolajal J. The effect of body mass index on endometrial cancer: a metaanalysis. Public Health. 2015;129(7):872-880.
- Liu Z, Zhang T-T, Zho JJ, et al. The association between overweight, obesity and ovarian cancer: a meta-analysis. Jpn J clin Oncol. 2015;45(12):1107-1115.
- Hu M-B, Liu S-H, Jiang H-W, Bai P-D, Ding Q. Obesity affects the biopsy-mediated detection of prostate cancer, particularly high-grade prostate cancer: a dose-response meta-analysis of 29,464 patients. PLoS One. 2014;9(9):e106677.
- Hidayat K, Du X, Chen G, Shi M, Shi B. Abdominal obesity and lung cancer risk: systematic review and meta-analysis of prospective studies. Nutrients. 2016;8(12):810-823.
- Zhang D, Chen J, Wang J, et al. Body mass index and risk of brain tumors: a systematic review and dose-response meta-analysis. Eur J Clin Nutr. 2016;70(7):757-765.
- Sergentanis TN, Tsivgoulis G, Perlepe C, et al. Obesity and risk for brain/CNS tumors, gliomas and meningiomas: a meta-analysis. PLoS One. 2015;10(9):e0136974.
- Schmid D, Ricci C, Behrens G, Leitzmann MF. Adiposity and risk of thyroid cancer: a systematic review and meta-analysis. Obes Rev. 2015;16(12):1042-1054.
- Orgel E, Genkinger JM, Aggarwal D, Sung L, Nieder M, Ladas EJ. Association of body mass index and survival in pediatric leukemia: a meta-analysis. Am J Clin Nutr. 2016;103(3):808-817.
- Majumder K, Gupta A, Arora N, Singh PP, Singh S. Premorbid obesity and mortality in patients with pancreatic cancer: a systematic review and meta-analysis. Clin Gastroenterol Hepatol. 2016;14(3):355-e32.
- Nagle CM, Dixon SC, Jensen A, et al. Obesity and survival among women with ovarian cancer: results from the Ovarian Cancer Association Consortium. Br J Cancer. 2015;113(5):817-826.
- Han J, Zhou Y, Zheng Y, et al. Positive effect of higher adult body mass index on overall survival of digestive system cancers except pancreatic cancer: a systematic review and meta-analysis. BioMed Res Int. 2017;2017:1049602. doi: 10.1155/2017/1049602
- Lin Y, Wang Y, Wu Q, et al. Association between obesity and bladder cancer recurrence: A metaanalysis. Clin Chim Acta. 2018;480:41-46.
- Bai P-D, Hu M-B, Xu H, et al. Body mass index is associated with higher Gleason score and biochemical recurrence risk following radical prostatectomy in Chinese men: a retrospective cohort study and meta-analysis. World J Surg Oncol. 2015;13:311-319.
- Schiffmann J, Salomon G, Tilki D, et al. Radical prostatectomy neutralizes obesity-driven risk of prostate cancer progression. Urol Oncol. 2017;35(5):243-249.
- Mei L, He L, Song Y, et al. Association between obesity with disease-free survival and overall survival in triple-negative breast cancer: a meta-analysis. Medicine (Baltimore). 2018;97(19):e0719.
- Playdon MC, Bracken MB, Sanft TB, Ligibel JA, Harrigan M, Irwin ML. Weight gain after breast cancer diagnosis and all-cause mortality: systematic review and meta-analysis. J Natl Cancer Inst. 2015;107(12):djv275.
- Gupta A, Majumder K, Arora N, et al. Premorbid body mass index and mortality in patients with lung cancer: a systematic review and meta-analysis. Lung Cancer. 2016;102:49-59.
- Shen N, Fu P, Cui B, Chun-Ying Bu C-Y, Bi J-W. Associations between body mass index and the risk of mortality from lung cancer. A dose–response PRISMA-compliant meta-analysis of prospective cohort studies. Medicine (Baltimore). 2017;96(34):e7721.
- Li S, Wang Z, Huang J, et al. Systematic review of prognostic roles of body mass index for patients undergoing lung cancer surgery: does the ‘obesity paradox’ really exist? Eur J Cardiothoracic Surg. 2017;51(5):817-828.