Allegheny General study finds obesity related to return of prostate cancer
There are many reasons for men to keep their weight under control, among them health risks that could lead to heart disease, stroke and diabetes.
Now Allegheny Health Network researchers who examined the cases of men who had prostate cancer surgery say they’ve found that patients who were obese were more likely to have their cancer return.
Urology department researcher Arash Samiei said AHN urology and oncology doctors shared their observations that led to the study, which looked back at all 1,100 surgeries done by two surgeons at Allegheny General Hospital between 2003 and 2013.
“We realized possibly there is a trend that most of the patients who had recurrence after taking the prostate out were more likely to be overweight or obese than regular patients,” Dr. Samiei said.
He shared a summary of their findings recently at a special conference on obesity and cancer held by the American Association for Cancer Research. Recurrence was determined by detectable levels of prostate-specific antigen in a PSA blood test.
The average age of patients when diagnosed was 60, and the average time of follow-up was 48 months after surgery. Of the total group, 34 percent were obese (with a BMI of 30 or higher) and 19 percent had metabolic syndrome. The patients were divided up into three risk groups, low to high, based on the stage and grade of their tumor.
In the high-risk group, 41.2 percent were obese, compared with 32 percent obese patients in the low and intermediate risk groups. Returning cancer was more common in patients with obesity (32.4 percent), compared with those with BMI below 30 (16.9 percent). Those with metabolic syndrome were found to have four times the risk of cancer recurrence, compared with those without it.
“There’s a trend in research that is trying to find the relationship between metabolic syndrome and other cancers,” Dr. Samiei said. Prostate cancer is the second-leading cause of cancer death in men (behind lung cancer). At the same time obesity and metabolic syndrome are becoming more common.
Metabolic syndrome is a cluster of conditions — high blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels.
“Over the past 20 years, it’s drastically increased,” Dr. Samiei said. “Obviously it’s because of the Western diet, the Western lifestyle.”
“This is very concerning right now among researchers and all health care providers. If we find a link, this is very preventable.”
Oncologist and prostate cancer researcher Leonard J. Appleman of the UPMC Hillman Cancer Center praised the AHN research: “It’s a very timely abstract they’ve published. … A retrospective study is a powerful tool. These findings are very important themselves.”
One reason they’re relevant, he said, is because prostate cancer tends to be a slow-growing disease: “There’s a lot of time for metabolic issues to influence the cancer.” For example, he said, stroke and heart problems may add to the patient’s risk of disease.
“It adds another reason to focus on a heart-healthy diet, a diet that will result in a healthy body mass index, both to reduce cardiovascular and metabolic disease. It will also make a difference in recurrence.”
He said losing weight can also benefit men with a high BMI who are treated after surgery with hormone therapy. Androgen-deprivation therapy aims to suppress the level of male hormones in the body and their influence on prostate cancer cells.
However, Dr. Appleman said, “Lowering testosterone has metabolic effects that are bad. There is more insulin resistance, and it raises the metabolic profile. There’s more belly fat. They lose muscle mass.”
Based on the Allegheny General data, those effects won’t help in the battle against recurrence of cancer, he said.
He agreed more studies are now needed, to follow patients as they enter treatment and beyond.
“It’s an opportunity to measure the impact of interventions — a diet and exercise regimen might have a positive effect on reducing body mass index — to try to measure the impact of cancer outcomes.”
He cautioned, “We have men who are lean who have cancer that doesn’t respond [to therapy], or behaves aggressively. There are also men who are overweight who have good results. … It’s not necessarily something obvious.”
Still, Dr. Samiei said patients with obesity and metabolic syndrome need to be followed more closely after surgery.
“We need to consider this a red flag. These patients have higher risk of cancer coming back.”