Harvard study: Obesity can accelerate growth of tumors

High-fat diet allows cancer cells to beat out immune cells for fuel

Obesity Affects More Than 4 out of 10 American Adults, Study Reveals Findings stem from a 2017-2018 health survey revealed by the CDC. It had over 5,000 participants whose weight was measured by their body mass index (BMI). According to the survey, 42 percent were found to be obese. In a 2015-2016 survey, the rate was 40 percent. Government researchers add that almost 1 in 10 U.S. adults are severely obese. Around 50 years ago, the severe condition was noted in just 1 in 100 adults. The survey's nu

Numerous studies have found how obesity affects a person’s health. According to Medical News Today, the health risks of carrying excess visceral fat also include: heart attacks, raised blood pressure, stroke, breast and colorectal cancer, and Alzheimer’s disease.

Visceral fat — which is stored in a person’s abdominal cavity — is also known as “active fat” because it influences how hormones function in the body. An excess of visceral fat can, therefore, have potentially dangerous consequences.

Now, a Harvard study has found that a high-fat diet allows cancer cells to outcompete immune cells for fuel, impairing immune function and accelerating tumor growth.

“Over the years, scientists have identified obesity-related processes that drive tumor growth, such as metabolic changes and chronic inflammation,” Harvard wrote in a press release published online by sciencedaily.com, “but a detailed understanding of the interplay between obesity and cancer has remained elusive.”

Researchers at Harvard Medical school said a high-fat diet reduces the numbers and antitumor activity of CD8+ T cells, a type of immune cell, inside tumors. This occurs because cancer cells reprogram their metabolism in response to increased fat availability to better gobble up energy-rich fat molecules, depriving T cells of fuel and accelerating tumor growth.

“Putting the same tumor in obese and nonobese settings reveals that cancer cells rewire their metabolism in response to a high fat diet,” said Marcia Haigis, professor of cell biology in the Blavatnik Institute at HMS and co-senior author of the study. “This finding suggests that a therapy that would potentially work in one setting might not be as effective in another, which needs to be better understood given the obesity epidemic in our society.”

The research team found that blocking this fat-related metabolic reprogramming significantly reduced tumor volume in mice on high-fat diets. CD8+ T cells are the main weapon used by immunotherapies that activate the immune system against cancer, Harvard wrote, and the results suggest new strategies for improving such therapies.

“We now know there is a metabolic tug-of-war between T cells and tumor cells that changes with obesity,” said co-senior author Arlene Sharpe, the HMS George Fabyan professor of comparative pathology and chair of the Department of Immunology in the Blavatnik Institute.. “Our study provides a roadmap to explore this interplay, which can help us to start thinking about cancer immunotherapies and combination therapies in new ways.”

The results serve as a foundation to better understand how obesity affects cancer and the effect of patient metabolism on therapeutic outcomes, the authors said.

The study was published Wednesday in the journal Cell.