In this Health Alert from the Prostate Bulletin, Dr. Jacek Mostwin and colleagues discuss five important risk factors for prostate cancer.
Age, race, and family history are important risk factors for prostate cancer. Diet and lifestyle factors may also influence whether a man develops the disease. No clear association has been found between the development of prostate cancer and smoking, vasectomy, the presence of benign prostatic hyperplasia (BPH), or regular alcohol intake (although binge drinking may increase the risk). Increasing evidence suggests that fat intake, physical inactivity, or being overweight may influence the development or progression of prostate cancer.
Age
As a man ages, his risk of developing prostate cancer increases dramatically. This age-related increase is greater for prostate cancer than for any other type of cancer. The average age at the time of diagnosis is between 65 and 70, and the average age of death is between 77 and 80.
Race
The incidence of prostate cancer in the United States varies by race. The rate for white men is 101 per 100,000 each year. Black men are at higher risk (137 per 100,000), and Asian Americans are at the lowest risk (20 to 47 per 100,000).
Family History
Studies of identical and fraternal twins show that prostate cancer has a stronger hereditary component than many other cancers, including breast and colon cancer. Having one first-degree relative (a brother or father) with prostate cancer doubles the risk of developing the disease; having a second-degree relative (an uncle or grandfather) with prostate cancer confers only a small increase in risk.
A number of genetic mutations are linked to prostate cancer. The best studied of these mutations are in a region of chromosome 1 known as HPC1. HPC1 may be involved in protecting against prostate inflammation. Some analyses have suggested that mutations in HPC1 increase the risk of prostate cancer, but other studies have failed to find an association. Other genes involved in how the body handles male hormones (androgens), its reaction to inflammation or infection, and its ability to process certain types of fat may also be important.
Although genes can influence a man’s risk of developing prostate cancer, other factors are also at work. The likelihood that identical twins (who share all genetic information) will both develop prostate cancer is 19% to 27%. This suggests that lifestyle choices can modify the effects of the genetic cards that a person is dealt at birth.
Environmental Factors
Much effort has been devoted to searching for environmental factors that might serve as promoters for prostate cancer. The incidence of microscopic prostate cancer (cancers too small to be seen except under a microscope) is similar among men in the United States and in all other countries that have been examined. However, the mortality rates from prostate cancer differ from one country to another and even within different regions of the United States. These differences suggest that environmental factors (such as diet, lifestyle, or exposure to certain substances or forces) influence prostate cancer’s progression from microscopic tumors to clinically significant ones.
Dietary fat
Most studies examining the relationship between dietary fat and prostate cancer have found that a higher fat intake (especially animal fat) is associated with an increased incidence of prostate cancer. Fat makes up 30% to 40% of the calories in the American diet, compared with 15% in Japan. This difference in fat consumption may help explain the much lower death rate from prostate cancer in Japan, as well as the great variability in prostate cancer mortality rates around the world. It is also possible that people who consume large amounts of high-fat foods are less likely to eat healthful foods that may protect against cancer.
