High BMI may improve survival in certain cancers: Study

Obese or overweight people may in some cases have improved chances of survival from certain cancers, claims a study which contradicts the regular warnings about the health risks posed by higher body mass index (BMI).

Above average or high BMI -- a measure of weight relative to height -- is often linked to cancers, diabetes, cardiovascular and other diseases, noted the researchers from Flinders University in Australia.

Focusing on clinical trials of atezolizumab, a common immunotherapy treatment for non-small-cell lung cancer (NSCLC), the researchers found improved responsiveness to the drug in those with a high BMI.

Of the 1,434 participants studied, 49 per cent were normal weight, 34 per cent were overweight and seven per cent were obese.

The findings, published in the journal JAMA Oncology, contrast with regular warnings about the health risks of patients who are overweight and obese.

"This is an interesting outcome and it raises the potential to investigate further with other cancers and other anti-cancer drugs," said Ganessan Kichenadasse, a medical oncology researcher at the Flinders Centre for Innovation in Cancer.

"We need to do further studies into the possible link between BMI and related inflammation, which might help to understand the mechanisms behind paradoxical response to this form of cancer treatment," Kichenadasse said.

Previous studies have explored a concept called as 'obesity paradox' where obesity is associated with increased risks for developing certain cancers and, counter-intuitively, may protect and give greater survival benefits in certain individuals.

"Our study provides new evidence to support the hypothesis that high BMI and obesity may be associated with response to immunotherapy," said Kichenadasse.

The researchers found NSCLC patients with BMI more than 25 kilogrammes per square metre in four clinical trials had a significant reduction in mortality with atezolizumab, apparently benefiting from immune checkpoint inhibitor (ICI) therapy.

Treatment options for this form of lung cancer are rapidly evolving and includes ICIs, molecular targeted drugs and chemotherapies, the researchers said.

"While our study only looked at baseline and during treatment, we believe it warrants more studies into the potentially protective role of high BMI in other cancer treatments," Kichenadasse said.

The World Health Organization (WHO) estimates at least 2.8 million people die each year as a result of being overweight or obese, the researchers said.

Overweight and obesity leads to adverse metabolic effects on blood pressure, cholesterol, triglycerides and insulin resistance, they said.

Risks of coronary heart disease, ischemic stroke and type 2 diabetes mellitus increase steadily with increasing BMI.