For American men, the lifetime risk of developing prostate cancer is 16%, while dying from the cancer is only 2.9%. Prostate cancer survival involves a number of factors, including the extent of the tumor at time of diagnosis, with more localized disease having better outcomes. However in autopsy studies, prostate cancer is found in 1/3 of men under 80 years old and 2/3 of older men, suggesting that prostate cancer grows so slowly that most men die of other causes before the cancer is clinically significant.
So while it is clear that early detection and treatment of prostate cancer improves treatment effectiveness, the benefits of screening men for it are less clear. The US Preventative Service Task Force recommends against screening, while both the American Cancer Society and American Urological Society emphasize individualized decision making. Ultimately, it is important for any man to discuss his personal risks and benefits of screening with his doctor before deciding.
As such, here are some questions everyone should consider before prostate cancer screening:
- Who is at an increased risk for prostate cancer?
Risk factors for prostate cancer include age (rarely occurs before age 40), ethnicity (more common in African-Americans), and family history of prostate cancer.
- What are the screening tests for prostate cancer?
1. Digital rectal exam (DRE): This exam allows the practitioner to feel the size and shape of the prostate gland. It can detect asymmetry, changes in consistency, or nodules in the prostate. However, only 85% of prostate cancers occur in a location that can be detected by the DRE. For this reason, it is usually used in conjunction with PSA (below).
2. Prostate specific antigen (PSA): PSA is a protein produced by the prostate and found in the blood. Conditions that may elevate the PSA include prostate inflammation/infection, benign enlargement of the prostate, and local trauma. One drawback of this test is that it cannot reliably distinguish between cancer, benign prostate enlargement, or inflammation.
- What happens after an abnormal screening test?
Confirmation of results by prostate biopsy is the next step. If cancer is found, the cancer is then staged and treated. However, even if no cancer is found, cancer may still be present because prostate biopsy is not a perfect test. Repeat biopsies may be needed. The complications of biopsy include pain, infection, rectal/urinary tract bleeding and urinary tract obstruction.
- What is the harm of screening?
Harm primarily occurs from unnecessary prostate biopsies. Screening may identify cancers that would never have become clinically significant. Patients are then subjected to unnecessary biopsies and the psychological stress of being diagnosed with cancer. Furthermore, patients with negative biopsy results may be distressed as biopsy results cannot conclusively rule out cancer, leading to chronic anxiety.
- What is the benefit of screening?
The goal of screening is early diagnosis and treatment so that cancers can be put into remission or even cured, with the ultimate objective being the prevention of deaths and decreasing mortality rates. However, of the two major trials (ERSPC & PLCO screening trial) investigating the effectiveness of prostate cancer screening, only the ERSPC showed a reduction in cancer deaths with screening. Both studies found prostate cancer screening did not affect a man’s overall mortality.
As always, if you have questions or concerns, it is best to meet with your physician.
Sources:
1 Ries, LAG, Melbert, D, Krapcho, M, et al (Eds). SEER Cancer Statistics Review, 1975-2004, National Cancer Institute, Bethesda, MD 2007.2 Dorr VJ, Williamson SK, Stephens RL. An evaluation of prostate-specific antigen as a screening test for prostate cancer. Arch Intern Med. 1993;153(22):2529.
3 Epstein JI. Pathology of prostatic neoplasia. In: Campbell’s Urology, 8th ed, Walsh PC (Ed), Saunders, Philadelphia 2002.
4 Bare R, Hart L, McCullough DL. Correlation of prostate-specific antigen and prostate-specific antigen density with outcome of prostate biopsy. Urology. 1994;43(2):191.5 Jung K, Meyer A, Lein M, Rudolph B, Schnorr D, Loening SA. Ratio of free-to-total prostate specific antigen in serum cannot distinguish patients with prostate cancer from those with chronic inflammation of the prostate. J Urol. 1998;159(5):1595
