In a recent study published in the Journal of the National Cancer Institute, a team of researchers followed thousands of midlife and older men for over 20 years and found that dynamic exercise and other healthy lifestyle behaviors may reduce the likelihood of their developing a lethal type of prostate cancer by up to 68%.
The majority of prostate cancers are not life-threatening. However, a minority of patients are diagnosed with aggressive prostate cancers that metastasize to the bone and other body organs, eventually leading to death. Several lifestyle factors have been associated with the risk of lethal prostate cancer, but little is known about their combined effect.
In the study titled “Development and Application of a Lifestyle Score for Prevention of Lethal Prostate Cancer,” Stacey Kenfield, ScD, from the University of California, San Francisco, and a team of researchers at UCSF and Harvard, retrieved and analyzed data from records of two studies conducted in the United States: the Health Professionals Follow-Up Study that followed 42,701 men, age 40 to 75 years, from 1986 to 2010; and the Physicians’ Health Study that followed 20,324 men, age 40 to 84, from 1982 to 2010.
The team developed a score to examine the consequences of lifestyle behaviors based on the results of the health professionals study, then applied this score to the physicians’ study. One point was given for each positive answer to queries concerning regular practice of intense exercise, high consumption of tomatoes, consumption of fatty fish, low consumption of processed meat, body mass index (BMI) below 30, and non-smoking status for at least 10 years.
To lessen statistical error, all participants were required to be free of diagnosed cancer at study’s start and a four-year lag was levied to exclude participants who might be unaware of having lethal prostate cancer, as later determined by evidence of “prostate cancer death or metastasis to the bones or other organs, excluding the lymph nodes.”
Energetic regular exercise most important lifestyle habit
Over the study period, the team identified 576 cases of lethal prostate cancer in the health professionals group, and 337 in the physicians’ group. Patients with a score of five to six points in the health professionals’ group and physicians’ group were found to have a decreased risk of lethal prostate cancer of 68% and 38%, respectively.
When the team considered dietary factors alone, the results revealed that men who scored three points, compared to those who scored zero, had a 46% decreased likelihood of developing lethal prostate cancer in the health professionals’ group, compared to a 30% decreased risk in the physicians’ group. Even though there were fewer cases and less detailed data collected in the physicians’ study, the score was identical in both populations. According to the authors, this indicates the potential benefit of healthy lifestyle behaviors in preventing lethal prostate cancer.
“We estimated that 47 percent of lethal prostate cancer cases would be prevented in the United States if men over 60 had five or more of these healthy habits,” Dr. Kenfield, assistant professor in the Department of Urology at UCSF Medical Center, and formerly of the Department of Medicine at Harvard Medical School in Boston, where the study was initiated, said in a press release. “It’s interesting that vigorous activity had the highest potential impact on prevention of lethal prostate cancer. We calculated the population-attributable risk for American men over 60 and estimated that 34 percent of lethal prostate cancer would be reduced if all men exercised to the point of sweating for at least three hours a week.”
The team also reported that lethal prostate cancer after age 60 years would be cut by 15% if men includedat least seven weekly portions of tomatoes in their meals. Moreover, 17% of men would not be diagnosed with lethal prostate cancer if they ate at least one portion of fatty fish weekly. Reducing processed meats consumption would cut the risk of lethal prostate cancer by 12%. Conversely, the population-attributed risk for smoking was 3%, mainly because the majority of midlife and older men in the United States are long-term non-smokers.
Lifestyle changes also prevent diabetes and heart disease
“This study underscores the ongoing need for more effective prevention measures and policies to increase exercise, improve diet quality and reduce tobacco use in our population,” said senior author June M. Chan, ScD, from the departments of Urology, and Epidemiology and Biostatistics at UCSF. “It takes co-operation and effort from multiple areas, like insurance companies, employers, policy makers and city planners, to figure out how to creatively support and encourage more exercise into most busy adults’ working day. These lifestyle habits align with other recommendations to prevent diabetes and heart disease.”
Prostate cancer usually develops slowly, so patients may not have any signs of the condition for years. Symptoms often only become apparent when the prostate is large enough to affect the urethra (the tube that carries urine from the bladder to the penis). Approximately one in every seven men will be diagnosed with prostate cancer during their lifetime, making prostate cancer the most commonly diagnosed cancer in the U.S., excepting non-melanoma skin cancer. Estimates from the American Cancer Society indicate that about 220,800 new cases of prostate cancer will be diagnosed in 2015 and nearly 27, 540 deaths will be due to this type of cancer.