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16-04-2021 | Oncology | News | Article

Outliers in link between obesity and poor cancer survival reinforced in meta-analysis

Hannah Kitt

medwireNews: Individuals with obesity tend to have worse cancer survival outcomes than those without obesity, unless they have lung cancer, renal cell carcinoma (RCC), or melanoma, show findings of a systematic review and meta-analysis.

“These results suggest that oncologists should increase their efforts to manage patients in multidisciplinary teams for care and cure of both cancer and obesity,” say Fausto Petrelli (Azienda Socio Sanitaria Territoriale Bergamo Ovest, Treviglio, Italy) and co-authors.

“Improving lifestyle factors (eg, physical activity, caloric intake, care and prevention of cardiovascular complications), more intensive follow-ups of cancer in patients with obesity, and adequate dose of medical therapies are all proven measures that may improve prognosis for patients with cancer and obesity,” they add.

In the analysis of 6,320,365 participants from 203 studies (63% retrospective, 31% prospective cohort or observational, and 4% pooled analyses or randomized trials), upwards of 20 different solid cancer types were included.

A pooled analysis of 170 studies with data for overall survival (OS) showed that patients with a BMI of 30 kg/m2 or more were significantly more likely to have worse OS than those with a lower BMI, with a hazard ratio (HR) of 1.14.

The researchers point out that this association was independent from other cancer prognostic factors, including tumor stage, age, sex, smoking status, and race as per multivariable analysis.

In subgroup analyses of individual cancer types, the association between obesity and poor OS remained significant for patients with breast (n=59 studies), colorectal (n=30), or uterine (n=12) cancer with respective hazard ratios (HRs) of 1.26, 1.22, and 1.20.

By contrast, among patients with melanoma, RCC, or lung cancer, the risk for death was significantly reduced for those with versus without obesity, at HRs of 0.74, 0.78 and 0.86.

The researcher note, however, that the lung cancer findings are based on just 11 studies, while the RCC and melanoma data were derived from five and one study, respectively.

Obesity was similarly associated with worse cancer-specific survival (CSS) and disease-free (DFS) or progression-free survival (PFS) in a pooled analysis of 109 and 79 studies, respectively, with corresponding significant HRs of 1.17 and 1.13 relative to no obesity.

And again there was a significant association between obesity and improved CSS in patients with lung cancer (HR=0.53) and between obesity and improved DFS or PFS among those with melanoma (HR=0.79), while the converse relationship held true for other tumor types, such as breast, colorectal, and prostate cancers.

Petrelli et al explain in JAMA Network Open: “Various factors are potentially associated with increased cancer mortality in some malignant neoplasms. Hormonal factors, reduced physical activity, more lethal or aggressive disease behavior, metabolic syndromes, and potential undertreatment in patients with obesity are possible reasons.”

They continue: “Intriguingly, we found that the association between obesity and better clinical outcomes was confirmed for those malignant neoplasms in which immune checkpoint inhibitors have first (and strongly) proved to be effective; however, studies involving patients receiving immune checkpoint inhibitors are poorly represented in this meta-analysis.”

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group

JAMA Netw Open 2021; 4: e213520

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