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As is the case with most cancers, the earlier prostate cancer is detected, the greater the odds of a cure. Proponents argue that a PSA screening is the only way to catch prostate cancer at an early stage. They also point to the fact that death rates from prostate cancer have decreased significantly since widespread screening began in the early 1990s.
The great news is that screening has dramatically increased the detection of prostate cancer while it is still localized to the prostate, a significant factor in improved outcomes.
It is now rare for men to be first diagnosed with prostate cancer when it is advanced. Deaths from prostate cancer have significantly declined in the last 20 years, which is great news by any standard.
The Disadvantages of PSA Screening
While the drop in deaths from prostate cancer is cause for celebration, opponents of PSA testing suggest that this has little to do with screening and more to do with treatment advances: The survival rate was already improving in the U.S., and survival rates have improved in countries that do not screen.
The case against screening points to these potential problems:
False negatives: The PSA test misses some cancers. Around 20 percent of men confirmed to have prostate cancer have normal PSA levels (less than 4 ng/ml). False negatives give a false sense of security.
Other causes of low PSA: Unfortunately, there are factors that naturally reduce PSA levels, further complicating the interpretation of results. These include:
- Cigarette smoking (past or present).
- Obesity: Greater blood volumes may dilute PSA.
False positives: Some 70 to 80 percent of men with elevated PSA levels do not have cancer. For these men, a positive test leads to a cascade of testing that often results in the man being told he doesn’t have cancer. That would be fine—if testing caused no harm. However, being told that you have a positive result may cause severe psychological stress for weeks or months.
And when a PSA test result raises suspicions of prostate cancer, the next test is prostate biopsy, which may cause complications such as infection, blood in the semen and/or urine, urinary symptoms, and, possibly, erectile dysfunction.
Other causes of high PSA: Unfortunately, there are factors that naturally increase PSA levels, further complicating the interpretation of results. These include:
- Prostatitis (non-cancerous inflammation), benign prostatic hypertrophy, and urine infections can all increase PSA
- Tests or surgery on the prostate, including DRE.
- Recent ejaculation, especially in older men.
- Exercise, most notably bicycle riding.
- Bypass surgery.
The unpredictability of positives: Statistically speaking, a very high PSA level is closely correlated to aggressive prostate cancer. But, when PSA is mildly elevated, the results are less clear-cut. Some men with high PSA turn out to have no cancer or a very slow-growing type, while some men with a low level of PSA turn out to have aggressive cancer. Research published in the journal Prostate International shows this latter scenario to be alarmingly common.
Number needed to treat: Statistics have measured the number of patients who need to be treated in order to prevent one extra bad outcome. In 2012, the European Randomized Study of Screening for Prostate Cancer trial showed that “to prevent one prostate cancer death, 935 men would need to be screened and 37 cancers would need to be detected.” Some researchers considered this rate to be unacceptably high.
PSA Screening Guidelines
The guidelines vary, so it falls to the individual clinician to decide which one(s) to follow. Patients should then be well informed so that a shared decision-making process can occur.
In 2012, the U.S. Preventive Services Task Force recommended against routine prostate screening in all men. However, in May 2018, the task force reversed its controversial stance and now advises that men ages 55 to 69 discuss the pros and cons of PSA screening with their physicians. The task force recommended against screening for men age 70 and older and men “who do not express a preference for screening.”
The American Cancer Society offers the following recommendations about prostate cancer screening.
- Step 1: Screening information to be provided to the following groups, so that an informed decision can be made:
- Men 50 and over with average risk.
- Men aged 45 to 50 with high risk, including African Americans and men with a first-degree relative (father, brother, son) diagnosed before age 65.
- Men aged 40 to 45 with highest risk (more than one first-degree relative diagnosed at an early age).
- Step 2: Men who opt for screening should be tested with a PSA test and DRE. If the man is unsure, he can ask his doctor to make the decision on his behalf.
- If PSA is below 2.5 ng/ml, a rescreening every two years is advised.
- For those with a higher PSA, annual screening is advised.
The National Comprehensive Cancer Network’s screening guidelines recommend:
- Step 1: Baseline history and physical examination, with a discussion of the risks and benefits of a baseline DRE and PSA.
- Step 2: Patient opts for a baseline DRE, which is normal. Then the following should be offered:
- Baseline PSA testing: Men ages 45 to 49.
- PSA is below 1.0 ng/ml: Retest every two to four years.
- PSA is 1.0 ng/ml or higher: Annual or biannual testing.
- If DRE is normal, PSA is below
3 ng/ml, and man’s age is 50 to 70: Retest every one to two years.
- Beyond the age of 75, only a select few should be screened.
The American Urological Association’s 2013 screening guidelines recommend screening for men aged 55 to 69 who have been fully informed and have made a shared decision with the clinician to go ahead with screening. Screening is recommended at intervals of at least two years.
Screening is not recommended for men in the following groups:
- Any man with a life expectancy of less than 10 to 15 years
- Men under 40 years or over 70
- Men between ages 40 to 54 years at average risk.
The European Society for Medical Oncology’s PSA screening guidelines recommend no screening for:
- Population-based PSA screening
- Asymptomatic men over 70 years old
- Men with a life expectancy of less than 15 years
PSA testing should be offered to these higher risk men:
- Over 50
- Over 45 with a positive family history
- African Americans over 45
- 40-year-old with a PSA level over 1 ng/ml
- 60-year-old with a PSA level over 2 ng/ml
For more information about PSA screening, purchase Prostate Diseases at www.UniversityHealthNews.com.