Prostate cancer is the most common non-skin cancer and the second leading cause of cancer mortality in American men. Despite the fact that this cancer will be diagnosed in an estimated 192,280 American men in the year 2009 and will lead to the death of approximately 27,360 men, there is no universally agreed-upon strategic plan for its diagnosis and management.
Epidemiology
Age The risk of developing prostate cancer begins to increase at age 50 years in white men who have no family history of the disease and at age 40 years in black men and those who have a first-degree relative (father, brother) with prostate cancer. Risk increases with age, but, unlike other cancers, prostate cancer has no “peak” age or modal distribution. There has been a downward “age migration” in the PSA (prostate-specific antigen) era such that the median age at diagnosis is now approximately 60 years old.
Race The highest incidence of prostate cancer in the world is found in American black men, who have approximately a 9.8% lifetime risk of developing this cancer. This rate is slightly higher than the 8% lifetime risk for American white men. Black men have an incidence of prostate cancer that is 1.6 times that of white men.
The Japanese and mainland Chinese populations have the lowest rates of prostate cancer. Interestingly, although Japanese immigrants to the United States have a higher incidence of prostate cancer than Japanese people living in Japan, their rate is still about half that of American whites.
Socioeconomic status appears to be unrelated to the risk of prostate cancer, and the explanation for racial variability is unknown. However, an interplay of diet, hormonal factors, and genetics likely accounts for the variability.
Geography The incidence of prostate cancer is highest in Scandinavian countries (22 cases per 100,000 population) and lowest in Asia (5 per 100,000). Risk may be inversely related to ultraviolet light exposure, as the incidence increases the farther one lives from the equator. However, recent studies show extremely high rates of prostate cancer in populations of African heritage, such as Jamaicans.
Etiology and risk factors
Family history Men who have a first-degree relative with prostate cancer have approximately a twofold increased risk of developing prostate cancer during their lifetime. An individual who has two first-degree relatives with prostate cancer has a ninefold increase in lifetime risk.
True hereditary prostate cancer occurs in a small number of men and tends to develop at an early age (< 55 years old).
Dietary fat Studies have suggested that dietary fat may increase the risk of prostate cancer. However, no definitive proof of its role has yet been found.
These studies indicate that progression of prostate cancer, which is likely to be more clinically relevant, has different risk factors than those associated with its initiation/incidence and that some of these risk factors are likely modifiable. Recent findings from the Health Professionals Follow-up study have, however, demonstrated different dietary risk factors for the incidence compared with progression of prostate cancer. For example, African-American race, a positive family history, low consumption of tomato products, and high consumption of alpha-linolenic acid have been associated with higher risks of incident prostate cancer. However, height, body mass index, low physical activity, smoking, low consumption of tomato sauce, high calcium and alpha-linolenic acid intake, African-American race, and positive family history have all been associated with more advanced cancer.
