At what age does screening for prostate cancer cease to provide value to the patient? In an article dated April 12, 2011, Gina Kolata, science journalist for the New York Times, examined this question with regard to prostate cancer. After reading in The Journal of Clinical Oncology that men in their 70s are screened for prostate cancer at almost twice the rate of men in their 50s and that men in their 80s are screened as much as men in their 30s, Ms. Kolata decided to see if she could find the answer. She uncovered more questions than answers.
The study, Population-Based Patterns and Predictors of Prostate-Specific Antigen Screening among Older Men in the United States, examined data from the 2000 and 2005 National Health Interview Survey. For the sake of the study, a PSA screening was defined as a PSA test as part of a routine exam within the past year.
The PSA screening rate was 24% among men age 50-54 years, and it increased with age to a peak rate of 45.5% among men age 70 to 74 years. Screening rates then declined by age with 25% of men age 85 years or older reporting a screening. Among men age 70 years or older, screening rates varied by 5-year life expectancy. Rates were higher among men with higher life expectancies and lower in men with low life expectancies (a difference of 47.3 % to 30.7% respectively).
The researchers were hoping to find different results. Going into the study, they thought that young healthy men who were likely to benefit from screening would be screened at higher rates, with screening trailing off in older men.
The American Cancer Society and the American Urological Society do not support screening for men whose life expectancy is below 10 years. Prostate cancer usually grows so slowly that most men die with the disease, not because of it. Because of the slow growing nature of most prostate cancer, for older men, screening may actually not be beneficial because if a diagnosis of cancer is made on biopsy, the treatments may not have a great impact on the course of the disease but often do have unpleasant side effects (including impotence and incontinence). Further, treatment might not cure many deadly prostate cancers because those cancers may have already spread outside the prostate.
The United States Preventive Services Task Force (USPSTF) is a bit more definitive with their recommendations, stating that screening should stop at age 75 for all men. USPSTF data suggest that screening over the age of 75 presents a ‘net-harm’ situation.
Even with the uncertainty, prostate specialists say that most men treated for prostate cancer would not have died of prostate cancer. The problem may not be with telling the patient he’s too old to test, but in convincing the physician that a time comes when the test should not be offered as a routine part of medical care. More studies are sure to follow.