Death From Prostate Cancer Linked to Weight at Diagnosis

November 9, 2013

A recent study shows that men who were overweight or obese at the time of their prostate cancer diagnosis were more likely to die from their disease compared with their healthy weight counterparts.

A recent study shows that men who were overweight or obese at the time of their prostate cancer diagnosis were more likely to die from their disease compared with their healthy weight counterparts. The results are published in the journal Obesity Research & Clinical Practice. For those who were diagnosed with more aggressive prostate cancer, being overweight had an even greater correlation with mortality risk.

Reina Haque, PhD, researcher in the department of Research and Evaluation at Kaiser Permanente in Pasadena, California, and colleagues analyzed 751 patients with prostate cancer who had a radical prostatectomy in this case-control study to better understand the link between body mass index (BMI) and mortality from cancer. The researchers used records of men from California, northwest Oregon, and southwest Washington who were diagnosed between 1971 and 2001.

The study included 323 men who had died of their disease, matched with 428 controls.

Each subject was categorized as healthy weight (BMI between 18.5 and 24.9), overweight (BMI between 25 and 29.9), and obese (BMI 30 or over). Almost 43% of the patients had a BMI greater than or equal to 25 at diagnosis. A greater proportion of men who died from their prostate cancer (30%) were obese compared with 22% of the men in the control group. After adjusting for Gleason score, prostate tumor antigen levels, and tumor characteristics such as lymph node status, obese men had a greater than 50% increase in mortality from prostate cancer (adjusted odds ratio of 1.5) when compared with men who had a healthy BMI.

Of the men who died from their prostate cancer, 82% were initially diagnosed with either stage II or III disease.

Grouping the men by aggressiveness of the prostate cancer as measured by Gleason score, the mortality risk increased with increasing BMI. The strongest effect was for men who had a Gleason score of 8 or greater-these men were 2.37 times more likely to die from prostate cancer compared with those who had a normal BMI at diagnosis.

Hague acknowledged that it is possible that poorer outcomes occur in obese men because obtaining clear surgical margins in these patients is more difficult during a prostatectomy. Still, the results “persisted even after we adjusted for multiple biologic and clinical factors such as tumor characteristics, Gleason score, comorbidities, PSA level at diagnosis, demographics, and lifestyle variables,” Hague said.

Additional prospective studies that analyze a larger population of patients are needed to support these results. Because men who eventually died of their prostate cancer were diagnosed relatively early, the authors suggest that weight loss may be beneficial and positively affect their cancer outcomes.

Because the study was restricted to those men who had surgery to treat their prostate cancer, whether these findings may apply to men who receive different forms of treatments for their prostate cancer besides surgery is still unclear. “This is an active area of research by Kaiser Permanente as well as other research teams,” said Haque.

The molecular mechanisms by which obesity could affect prostate tumor development and growth are unclear. Previous studies suggest that insulin signaling which is linked to cancer initiation and progression is increased in obese patients. Obesity may also influence male hormone levels.

The authors also suggest that BMI may be “a surrogate marker for other factors associated with poor prostate cancer outcomes, such as lower physical activity or poor diet.”

Hague and colleagues are now planning to extend these results by analyzing recent cases and including those men treated with radiation therapy and active surveillance.

“Clinicians and patients should be aware of the growing body of evidence that associates weight and prostate cancer mortality,” said Hague. “Clinicians should also be aware of future studies that [may] provide information regarding whether weight loss or other lifestyle changes could prolong a prostate cancer patient’s life.”