TUESDAY, April 20 (HealthDay News) -- Men treated for prostate cancer who smoke or put on excess pounds raise their odds of disease recurrence and of dying from the illness, two new studies show.
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The findings were presented Tuesday at the American Association for Cancer Research's annual meeting in Washington, D.C.
In the first report, a team led by Dr. Jing Ma, an associate professor of medicine at Brigham and Women's Hospital in Boston, found that obesity and smoking may not be risk factors for developing prostate cancer, but they do increase the odds that a man who has the illness will die from it.
Being heavy and smoking "predispose men to a significantly high risk of cancer-specific and all-cause mortality," Ma said during a Tuesday morning news conference.
"Compared to lean non-smokers, obese smokers had the highest risk of prostate cancer mortality," she said.
For the study, Ma's team collected data on more than 2,700 men with prostate cancer who took part in the Physicians Health Study. Over 27 years of follow-up, 882 of the men died, 11% from the cancer.
The researchers found that both weight gain and smoking boosted the risk for dying from the cancer. In fact, every five-point increase in body mass index (BMI) increased the risk for dying from prostate cancer by 52%. BMI is a measurement of height versus weight, with the threshold of overweight set at a BMI of 25 and the threshold for obesity set at a BMI of 30.
In addition, men who smoked increased their risk for dying from the cancer by 55%, compared with men who never smoked, the study found.
"These data underscore the need for implementing effective preventive strategies for weight control and reducing tobacco use in both healthy men as well as prostate cancer patients," Ma said.
In a second report, a team led by Corinne E. Joshu, a postdoctoral fellow in the department of epidemiology at Johns Hopkins Bloomberg School of Public Health, found that men who gained weight after having their prostate removed were almost twice as likely to see their cancer return as were men who maintained their weight.
"Weight gain may increase the risk of prostate cancer recurrence after prostatectomy," Joshu said during the AACR news conference. "Obesity, especially among inactive men, may also contribute to the risk of prostate cancer recurrence," she said.
For the study, Joshu's team collected data on more than 1,300 men with localized prostate cancer who underwent prostatectomy between 1993 and 2006. In addition, the men completed a survey on diet, lifestyle and other factors such as weight, height and physical activity five years before surgery and again one year after the procedure.
By the end of the study in 2008, 102 men saw their prostate cancer return. These men were older, more likely to have more aggressive tumors and less likely to have a family history of prostate cancer, compared with men whose cancer did not return, the researchers found.
Furthermore, men who had gained at least five pounds before surgery or up to one year after surgery had almost a two-fold greater chance of seeing their cancer return than did men who did not gain weight, Joshu said.
Five years before undergoing a prostatectomy, 54% of the men were overweight and nine percent were obese. Among men who gained weight in the year after surgery, the average weight gain was about 10 pounds. Becoming obese after surgery increased the risk for a recurrence of prostate cancer 1.7-fold, the researchers said.
"By avoiding obesity and weight gain," Joshu said, "men with prostate cancer may be able to both prevent recurrence but also improve their overall well-being."
In another report presented Monday at the meeting, Katherine A. McGlynn, a senior investigator at the U.S. National Cancer Institute, said that the proper control of diabetes might cut people's odds of developing liver cancer.
The researchers used the SEER-Medicare linked database to collect data on more than 5,600 people diagnosed with liver cancer. Among them, 63% of the cancers were associated with conditions such as diabetes, alcohol-related disorders and hepatitis C, chronic hepatitis B, obesity and several rare metabolic disorders. The relationship was highest for Asians, at 67.9%, and lowest for blacks, at 53.5%, the researchers noted.
Among the risk factors, the leading cause of liver cancer was diabetes (33.5%). Other factors determined to be contributors to liver malignancy were alcohol-related disorders (23.9%), hepatitis C (20.7%), hepatitis B (5.7%), rare metabolic disorders (3.1%) and obesity (2.7%).
That left 37% of liver cancers with indeterminate origins, McGlynn noted. "We have a long way to go because one-third of the tumors are not explained by these risk factors," she said during Tuesday's news conference.
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SOURCES: April 20, 2010, teleconference with Jing Ma, M.D., Ph.D., associate professor, medicine, Brigham and Women's Hospital, Boston; Corinne E. Joshu, M.P.H., Ph.D., postdoctoral fellow, department of epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore; Katherine A. McGlynn, Ph.D., M.P.H., senior investigator, U.S. National Cancer Institute, Bethesda, Md.; April 20, 2010, presentations, American Association for Cancer Research annual meeting, April 17-21, 2010, Washington, D.C.