Prostate Cancer Screening
Background
Screening is a process whereby people are checked for cancer in the absence of any symptoms. There is intense controversy regarding the utility of screening. Two large scale randomized trials have not clarified the situation and there are differing opinons regarding the utility of screening from major medical organizations. There are some facts which are important to consider when discussing the merits of screening for prostate cancer.
Up to 20% of men will receive a diagnosis of prostate cancer during their life, the majority as a result of screening.
Prostate cancer is a slowly progressive disease in most (but not all) men. Many men will die of causes other than prostate cancer, even if the cancer is untreated.
Men do die from prostate cancer - prostate cancer is a lethal disease in 3-4% of men. Therefore, approximatly 1 in 5 men who receive a diagnosis of cancer will die of it.
Many men with prostate cancer neither need nor benefit from treatment. The treatments themselves may be harmful.
Radical prostatectomy has been proven to significantly decrease the chances prostate cancer spread and death from prostate cancer. A caveat to this trial is that men were not detected with screening.
Therefore, there is a balance between the harms and benefits of prostate cancer screening. The men most likely to benefit will be those that have the highest chance of having an aggressive cancer and are likely to live long enough to suffer from prostate cancer.
The Process of Screening for Prostate Cancer
Screening for prostate cancer involves regular assessment of asymptomatic men as part of routine health checks. Ideally, the process takes into account:
For men with a life-expectancy less than 10 years, screening for prostate cancer is not recommended. This works out to about age 70 in Canadian men since the average life expectancy is 81 years of age. Every man is different, however, and some men may receive benefit from screening if they are in above-average health. Note that checking a man for prostate cancer with a life expectancy less than 10 years and symptoms which may be due to prostate cancer would not be considered screening.
Armed with the knowledge of the risk of harboring an aggressive prostate cancer, life expectancy, the natural history of untreated prostate cancer, and the risks and benefits of treatment a man can make an informed decision on whether to undergo a biopsy. In general, you will receive a recommendation based on this assessment to:
Undergo a biopsy (the recommendation may be weak, moderate or strong)
Increase the intensity of screening with a repeat PSA and DRE
Discontinue or continue with routine screening
Controversies in Prostate Cancer Screening
There is intense controversy regarding screening for prostate cancer. The major issue is that definitive evidence that the net benefits outweigh the risks is not available. Unquestionnably, screening results is earlier diagnosis of prostate cancers which are more likely to be localized. Intuitively, one would expect that this would lead to improved survival, but proving this has been elusive. There have been 2 large scale randomized controlled trials on prostate cancer screening - one in Europe and another in North America. Despite the fact that these trials are the best information available, there are serious methodological issues which severely limit their applicability. The European trial demonstrated a modest survival benefit from screening and subsequent treatment at 10 years of follow-up whereas the US trial did not. It is possible that with prolonged follow-up, screening will be shown to have a more profound impact on overall survival from prostate cancer.
Medical groups which recommend prostate cancer screening: American Urological Association, American Cancer Society
Medical groups which do not recommend prostate cancer screening: American College of Physicians, US Preventative Services Task Force