Can weight loss slow prostate cancer?

You've had a biopsy and have been diagnosed with low-grade prostate cancer, defined as a tumor that is confined to the prostate gland and unlikely to grow or spread. You decide to follow active surveillance, a protocol in which you regularly follow up with your doctor for routine PSA tests, prostate biopsies, and possibly MRI scans. If at some point it looks like the cancer has progressed, then you can consider treatment (radiation or surgery).

For some men, this wait-and-see period lasts for years. But can you do anything to help slow your cancer's growth and delay treatment for as long as possible? Your bathroom scale might give you the answer.

How monitoring works

The reality is that most low-grade prostate cancer does not transform over time and become more aggressive, according to Dr. Mark Pomerantz, a medical oncologist with Harvard-affiliated Dana-Farber Cancer Institute.

"Being on active surveillance is more about looking out for cancer that the original biopsy missed," he says. "It's not necessarily that the original low-grade cancer becomes more aggressive — although that is possible in some cases — but rather, high- or medium-grade cancer is hiding and we're looking for changes in PSA levels that might suggest it's there and become aggressive."

About 45% to 60% of men on active surveillance will not need cancer treatment over the 10 to 15 years following their initial diagnosis, according to Dr. Pomerantz. While those are encouraging figures, they still leave the chance you may need treatment sooner.

Controlling factors

You can't control two factors that can increase the risk of undetected high- or medium-grade cancer from becoming aggressive: genetics and family history. But one aspect you may be able to change is your weight.

"While excess weight doesn't appear to increase the likelihood of low-grade prostate cancer, there appears to be a strong association between being overweight or obese and the risk of developing aggressive prostate cancer," says Dr. Pomerantz. People with a body mass index (BMI) of 25 to 29.9 are considered overweight, while those with a BMI of 30 or higher are classified as obese.

Scientists reported in the Aug. 15, 2019, issue of Cancer that over a 10-year period, men diagnosed with prostate cancer whose waist size and BMI increased the most had greater risks of advanced and fatal prostate cancer compared with men who maintained a healthy weight.

Specifically, a five-point increase in BMI was associated with a 50% higher risk for advanced or fatal prostate cancer, and a 4.1-inch increase in waist size was associated with a 40% higher risk. Where that extra fat lies also is a driving a factor. The same study discovered that extra visceral fat (the hidden kind that lies deep in the abdomen and surrounds the major organs) was linked with a 31% higher risk of developing advanced prostate cancer.

Your past weight gain also may play a role in future cancer growth, suggests research presented at the European Congress on Obesity in May 2023. Researchers found that men who gained an average of 2.2 pounds each year from ages 17 to 29 increased their risk of developing aggressive prostate cancer later in life by 13%.

"So losing excess weight may be one way to possibly keep prostate cancer from growing more rapidly," says Dr. Pomerantz.

The weight connection

Experts don't fully understand the relationship between excess fat and prostate cancer growth. Some theories suggest that extra weight leads to higher levels of inflammation, which in turn acts like fuel to prostate cancer cells. Overweight and obese men also are more likely to have higher levels of blood sugar, which stimulates the pancreas to release more insulin. Some studies have shown a link between higher insulin levels and an increased risk of prostate cancer. "This could be another factor raising the chance of more aggressive cancer," says Dr. Pomerantz.

While weight loss and weight management are never easy, Dr. Pomerantz says many men on active surveillance often embrace the situation as an opportunity to make overall health changes.

"Increasing exercise and adopting a healthy, plant-based diet, both of which can help men lose extra pounds, not only can help with their prostate cancer, but can reduce their risk of heart disease and other cancers," he says. "Most men on active surveillance will die of something other than prostate cancer, so this can be a wake-up call for men to get serious about their health."

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