Cancer Outcomes

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.

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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

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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.


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