A Patient’s Guide to Prostate Cancer Screening
Currently, doctors disagree about the issue of prostate cancer screening. This issue is whether men without symptoms should be tested for prostate cancer. Controversy exists because screening has both potential advantages and known disadvantages. Studies are currently underway to assess the value of screening, but the results will not be available for over a decade. Until more knowledge is gained, patients should make the decision about prostate cancer screening in conjunction with their doctors. The following information is intended to help you in making this decision. Any questions that you have after reading this material should be discussed with your doctor. The Case For Screening • Advanced prostate cancer is not curable • Without screening, only a small percentage of men will be diagnosed with prostate cancer at an early, more curable stage • Prostate Cancer detected at an early stage may be more likely cured. • PSA testing improves early detection • Sequential screening (i.e. annually) may offer more benefit than one-time screening. The Case Against Screening • No study has proven that screening reduces a man’s risk of dying from prostate cancer • Most men with prostate cancer will die from other causes, making detection neither necessary nor beneficial • Current therapy of prostate cancer has a significant risk of permanent complications such as impotence and urinary incontinence • Possibility of false positive result, requiring further invasive testing without benefit. The following general information applies to prostate cancer screening. 1. Both the benefits and risks of screening should be discussed with the patient before testing is performed and patients should share in the decision making process. 2. Some men may derive significant benefit while others are likely to be harmed by screening and subsequent treatment. 3. As men get older, the chance of screening being beneficial decreases. 4. Screening is most likely to benefit men aged 50-70 years and less likely to benefit those who are older. 5. Screening may also benefit those men at increased risk of getting prostate cancer. Known risk factors include African-American race and a family history of prostate cancer. In African-American race and/or a family history of prostate cancer, screening should begin at age 40. 6. If screening is done, it should consist of a PSA and rectal examination. 7. If either test is abnormal, the patient may choose to receive further testing to rule out cancer.
BASED ON THIS INFORMATION, IF HAVE DECIDED TO:
______Have the PSA test
______Not have the PSA test
Signature:_______________________________________
Date:________________________
Revised: 8/98 Sean Rogers, MD
UCSD MEDICAL GROUP
Prostate Cancer Screening
Educate men aged 50-70 with patient education materials
Discuss risks and benefits of screening with patient
Patient desires screening?
YES NO
DRE and PSA No screening: re-discuss annually
ABNORMAL? (PSA > 4 or palpable abnormality on DRE)
YES
NO
Urology referral
Repeat screening annually with patient consent
This guideline is to be used to assist in clinical efficiency, but is not a substitute for clinical judgement.
Revised: 8/98 Sean Rogers, MD
UCSD MEDICAL GROUP
Prostate Cancer Screening Scope of the problem Prostate cancer is a highly prevalent disease and is the number one newly diagnosed cancer in men. US estimates for 1997 predicted 334,500 new cases of prostate cancer and 41,800 deaths. The lifetime risk of dying form prostate cancer in American men is 3.4%. The lifetime risk of getting prostate cancer is 1 in 5. Autopsy studies suggest that undiagnosed prostate cancer is present in 30% of men over the age of 50. The three risk factors most clearly associated with prostate cancer are increasing age, African-American race, and family history. Current recommendations The following governing bodies recommend against routine prostate cancer screening: the American Cancer Society, the American College of Physicians, the United Stated Preventive Services Task Force, the Canadian Task Force on the Periodic Health Examination, and the American Academy of Family Physicians. Only the American Urological Association still recommends routine screening for men over the age of 50. With the data currently available, the following recommendations seem reasonable. Routine screening for prostate cancer without patients’ knowledge or consent is inappropriate. Because of life expectancy, screening in men over the age of 70 is not recommended. Screening should be offered to men at high-risk (i.e. African-American race or positive family history) beginning at age 50. Screening may be initiated at an earlier age in men at an earlier age in men with multiple risk factors, based on individual evaluation. Patient involvement and education regarding the risks/benefits of screening is crucial. The decision to screen should be individualized to each patient. Screening should not be denied to those patients who request it. Current screening modalities The two most widely used screening tests are the digital rectal examination (DRE) and prostate specific antigen (PSA). Due to its significantly lower sensitivity, prostatic acid phosphatase has been largely replaced by PSA. Transrectal ultrasound (TRUS) should not be considered a primary screening modality secondary to issues of cost, patient acceptance, and availability. The true sensitivity and specificity of DRE and PSA are unknown because the gold standard (i.e. prostatic biopsy) is usually not obtained in men with normal DRE’s or PSA’s. DRE has limited sensitivity because only the posterior lobe of the prostate is examined and Stage A cancers are, by definition, nonpalpable. The specificity of DRE is also limited. The positive predictive value (PPV) has been reported to range from 6-33%. A PSA value over 4 ng/dL has a reported sensitivity of 70-90% for prostate cancer but a specificity of only 3864%. The PPV for PSA is 28-35%. PSA can be falsely increased following TURP or cystoscopy, or in BPH, prostatis, prostatic infarct, and acute urinary retention. PSA can be falsely decreased in hospitalized patients and in men taking finasteride. PSA is neither increased nor decreased by DRE, physical exercise, nor alpha blockers. The combination of an abnormal DRE and PSA yields a PPV of about 50%. Thus, a man who has a palpable prostatic abnormality and a PSA > 4 ng/dL has a 50% chance of being diagnosed with prostate cancer after further invasive testing. Screening Currently, there is little data to suggest that routine prostate cancer screening results in decreased specific morbidity and mortality. It is know that widespread use of screening techniques has led to an increase in the detection of early stage cancers but the natural history of these frequently indolent cancers is unknown and the efficacy of treatment with radical prostatectomy or radiation therapy is unproven. Survival varies inversely with the clinical stage at diagnosis and 5 year survival approaches 90% in untreated early stage prostate cancer (Kramer, Woolf).
UCSD MEDICAL GROUP
Prostate Cancer Screening Screening(continued) The exact impact of lead-time and length biases on the current studies is unknown. Survival also depends on histological grade. A meta-analysis of six studies involving 762 men showed a 10 year survival rate of 87% in men with well differentiated cancers (Chodak). Another recent trial followed 642 men diagnosed with prostate cancer for 15 years and found no difference in 10 and 15 year survival curves between those who received treatment and those who had expectant management (Johansson). Only one randomized controlled trial has compared expectant management to radical prostatectomy and 15 year follow up showed no difference in survival curves. However, the study suffered from design flaws and involved only 111 men (Graversen). Trials in progress Two large trials currently in progress will hopefully provide some definitive answers about prostate cancer screening. Both are long term trials with results not available for over a decade. The Prostate cancer Intervention Versus Observation Trial (PIVOT) has enrolled 2,000 men less than 75 years of age and will compare radical prostatectomy versus observation in clinically localized prostate cancer (Wilt). The prostate cancer arm of the National Cancer Institute’s Prostate, Lung, Colorectal, and Ovarian cancer screening trial (PLCO) will enroll 74,000 men aged 60-74 without prostate cancer and compare screening with PSA and DRE versus routine health care (Gohagan). Both of these trials will address disease specific morbidity and mortality for prostate cancer. References and general reading Cancer Statistics, 1997. CA Cancer J Clin. Chodak et al. NEJM. 1994. 330 (4): 242-8. Coley, CM et al. Annals of Internal Medicine. 1997 126 (5): 394-406; 126 (6): 468-79, 480-90. Gohagan et al. Journal of Urology. 1994 152 (5 pt 2): 1905-9. Graverson et al. Urology. 1990. 36 (6): 493-501. Johansson et al. JAMA. 1997. 277 96): 467-71. Kramer, BS et al. Annals of Internal Medicine. 1993. 119 (9): 914-23. Wilt, TJ. Journal of Urology. 1994. 152 (5 pt 2): 1910-1. Woolf, SH. United States Preventive Services Task Force. 1996. 119-34.