Exercise linked with reduced prostate cancer risk in Caucasians but not African Americans
A new study suggests that exercise may reduce Caucasian men’s risk of developing prostate cancer. And among Caucasian men who do have prostate cancer, exercise may reduce their risk of having more serious forms of the disease. Unfortunately, the benefits do not seem to apply to African- American men. The study is published early online in CANCER, a peer-reviewed journal of the American Cancer Society.
Previous research has linked exercise to a reduced risk of developing prostate cancer. Studies have also revealed that African-American men have an increased risk of developing prostate cancer and of dying from the disease compared with Caucasians. It is not clear if exercise as a function of race plays any role in these disparities.
To investigate, Lionel L. Bañez, MD, of the Durham Veterans Affairs Medical Center, and his colleagues asked 307 men (164 white; 143 black) undergoing a prostate biopsy to complete a survey that assessed their exercise amounts per week. The exercise categories included sedentary, mildly active, moderately active, and highly active. Among Caucasians, men who were moderately or highly active were 53% less likely to have biopsy results indicating that they had prostate cancer compared with men who were sedentary or mildly active. There was no association between exercise amount and prostate cancer among black men.
The investigators also looked to see if exercise influenced the grade of tumors that were detected in men who did develop prostate cancer.
Among men with cancer, those who exercised had a 13% reduced risk of having high grade disease, meaning that their cancer cells looked particularly abnormal under a microscope and were likely to quickly grow and spread. When this relationship was further explored as a function of race, it remained significant in Caucasians but not in African Americans.
What is Prostate Cancer?
Prostate cancer is an abnormal growth of cells in the prostate that form a lump (tumour). In time, without treatment, it may spread to other organs, particularly the bones and lymph nodes, which can be life threatening. Generally at the early and potentially curable stage, prostate cancer does not have obvious symptoms. This makes it different from other benign prostate disorders, which may result in urinary symptoms.
“These findings that African-American men may not benefit from exercise the way Caucasian men do could be a contributor to why African- American race is a risk factor for prostate cancer and aggressive prostate cancer. Further studies are needed to investigate the mechanism behind this racial disparity in deriving cancer-related benefits from exercise which disfavors African-American men,” said Dr. Bañez.
Prostate cancer is the most common non-skin cancer in America, affecting 1 in 6 men. But who is most at risk of getting prostate cancer and why?
There are several major factors that influence risk, and some of them unfortunately cannot be changed.
Age: The older you are, the more likely you are to be diagnosed with prostate cancer. Although only 1 in 10,000 men under age 40 will be diagnosed, the rate shoots up to 1 in 38 for ages 40 to 59, and 1 in 15 for ages 60 to 69.
In fact, more than 65% of all prostate cancers are diagnosed in men over the age of 65. The average age at diagnosis of prostate cancer in the United States is 69 years. After that age, the chance of developing prostate cancer becomes more common than any other cancer in men or women.
Race: African American men are more likely to develop prostate cancer compared with Caucasian men and are nearly 2.5 times as likely to die from the disease. Conversely, Asian men who live in Asia have the lowest risk.
Family history/genetics: A man with a father or brother who developed prostate cancer is twice as likely to develop the disease. This risk is further increased if the cancer was diagnosed in family members at a younger age (less than 55 years of age) or if it affected three or more family members.
Where you live: For men in the U.S., the risk of developing prostate cancer is 17%. For men who live in rural China, it’s 2%. However, when Chinese men move to the western culture, their risk increases substantially.
Men who live in cities north of 40 degrees latitude (north of Philadelphia, PA, Columbus, OH, and Provo, UT, for instance) have the highest risk for dying from prostate cancer of any men in the United States. This effect appears to be mediated by inadequate sunlight during three months of the year, which reduces vitamin D levels.
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Amy Molnar
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Wiley