WASHINGTON, D.C.—Weight gain in the five years before and one year after radical prostatectomy (RP) for prostate cancer (PCa) could increase the risk of disease recurrence, investigators reported here at the 101st Annual Meeting of the American Association for Cancer Research.
Men who are obese one year after RP, especially sedentary and inactive men, also are at increased risk of recurrence.
“Obesity and weight gain may be factors that tip the scale to recurrence,” said study investigator Corinne Joshu, PhD, MPH, a postdoctoral fellow at Johns Hopkins Bloomberg School of Public Health in Baltimore.
Prior research has shown that obesity at or near the time of RP is associated with an increased risk of recurrence. Whether weight gain in the years prior to surgery is associated with recurrence has been unclear. In addition, no studies have looked at sedentary behavior and whether it exacerbates the obesity-related risk of recurrence.
Dr. Joshu and her colleagues retrospectively studied 1,337 men with clinically-localized prostate cancer. Subjects had undergone RP at Johns Hopkins between January 1993 and March of 2006. None of the patients previously had hormone or radiation therapy. The investigators followed up the men for recurrence, metastasis, or prostate cancer death. They sent patients a survey questionnaire asking about dietary, lifestyle, and medical factors, including weight, height, physical activity, and sedentary behavior for the five years prior to surgery and one year after.
At the time of surgery, the 102 men who had recurrence were older than the 1,235 men who did not (mean age 58.1 vs. 56.3 years), were less likely to have a family history of PCa (14.7% vs. 27.7%) and more likely to have poorer pathological tumor characteristics. Five years before surgery, 54% of men were overweight and 9% were obese. Men whose BMI increased by 1 kg/m2 or more from five years before surgery to one year after were twice as likely to have recurrence as men who had a stable BMI. In addition, men who were obese one year after RP were 1.67 times more likely to have recurrence than men with normal BMI. In the obese group, sedentary behavior and inactivity were associated with a 2.65 and 2.30 increased risk.
“The good news is that being physically active reduced the risk of recurrence associated with obesity,” said study co-investigator Elizabeth Platz, ScD, MPH, Associate Professor of Epidemiology at Johns Hopkins.
A variety of biochemical pathways may be active in the body depending on daily activity, and these pathways may vary in their impact depending on the stage and type of prostate cancer and timing of obesity and weight gain. “There are several metabolic issues that may be involved, including an increase in growth factors and increased inflammation,” Dr. Joshu said.
The study size was too small to determine whether weight loss can reverse recurrence risk. In addition, several confounding factors may have had an impact on the results, including patients’ ability to accurately recall their weight and lifestyle around the time of their surgery. Dr. Joshu noted that PSA values tend to be lower in obese men, and this could delay detection of recurrent disease. If that is the case, she said this study may have underestimated the risk of recurrent disease in the obese men.