Prostate cancer
Prostate cancer is a common type of cancer among men. Treatment for prostate cancer works best when the disease is found early.
Epidemiology
Among men who died and were organ donors, the prevalence at prostate cancer at autopsy was:[1]
- age <50: 0.5% had prostate cancer
- age 50–59: 23% had prostate cancer
- age 60-69: 35% had prostate cancer
- age 70 or more: 46% had prostate cancer
Diagnosis
Early prostate cancer does not usually cause symptoms. As the cancer grows, it may cause trouble urinating, and the need to urinate often, especially at night. Other symptoms can be pain or burning during urination, blood in the urine or semen, pain in the back, hips, or pelvis, and painful ejaculation.
To figure out if these symptoms are caused by prostate cancer, the doctor will ask the patient questions about past medical problems, and will perform a physical exam, putting a gloved finger into the rectum to feel the prostate through the wall. Hard or lumpy areas may be a sign of cancer.
The doctor may also do a test to check the prostate-specific antigen (PSA) level in the blood. PSA levels may be high in men who have an enlarged prostate gland or prostate cancer.
It may also need to have an ultrasound exam. In this procedure, a probe that produces sound waves is put into the rectum. Sound waves bounce off the tissues, and a computer uses the echoes to make a picture of the prostate.
A biopsy is almost always needed to diagnose prostate cancer for sure. This exam takes out tiny pieces of the prostate and sends them to a laboratory to be checked for cancer cells under a microscope.
Prognosis
Gleason score
The Gleason score is the "sum of the numbers associated with the most common histologic pattern plus the secondary pattern."[2] The two numbers are based on the histologic grade:
| Gleason histologic grade | prognosis |
|---|---|
| 1 - 2 | well differentiated |
| 3 | moderately differentiated |
| 4 | poorly differentiated |
| 5 | undifferentiated |
| Gleason score (sum of the primary and secondary histologic grades) |
prognosis |
|---|---|
| < 6 | indolent |
| 6 - 8 | intermediate |
| > 8 | aggressive |
A clinical prediction rule is available at http://www.prostate-riskindicator.com/en/w6-intro.html.
Staging
Prostate cancer staging information from the National Cancer Institute's Physician Data Query
Treatment
Prostate cancer treatment information from the National Cancer Institute's Physician Data Query
The choice of treatment depends on the stage of the cancer (whether it affects part of the prostate, involves the whole prostate, or has spread to other parts of the body). It also depends on the patient age and general health. There are three treatment options for cancer that has not spread beyond the prostate; however, a systematic review for the Agency for Healthcare Research and Quality concluded that " Assessment of the comparative effectiveness and harms of localized prostate cancer treatments is difficult because of limitations in the evidence."[4]
Watchful waiting. If the cancer is growing slowly and not causing problems, is possible to decide not to have treatment right away. Instead, the doctor will check regularly for changes in the patient condition. Older men with other medical problems often choose this option.
Surgery. The most common type of surgery is a radical prostatectomy. The surgeon takes out the whole prostate and some nearby tissues. Side effects may include loss of sexual function (impotence) or problems holding urine (incontinence), which can go away within a year of surgery. But some men continue to have problems and have to wear a pad. An operation called nerve-sparing surgery gives some men a better chance of keeping their sexual function.
Radiation therapy. This treatment uses high-energy x-rays to kill cancer cells and shrink tumors. There are two kinds of radiation therapy. External radiation therapy is beamed into the prostate from a machine outside the body. Internal radiation therapy uses radioactive “seeds” that are placed in the prostate, into or near the tumor itself. Like surgery, radiation therapy can cause problems with impotence, not as likely to cause urinary incontinence as surgery. But it can cause rectal problems such as pain and soreness, rectal urgency, and trouble controlling bowel movements.
In addition, after radiation therapy, some men are treated with hormone therapy. This is used when chances are high that the cancer will come back. Hormone therapy is also used for prostate cancer that has spread beyond the prostate. Side effects of hormone treatments include hot flashes, loss of sexual function, and loss of desire for sex.
Screening
Some doctors think that men should have regular prostate specific antigen (PSA) tests, and others do not. The reason is even knowing that this test can catch a cancer before it causes symptoms, it is not sure that PSA tests save lives. Also, PSA tests find small cancers that would never grow or spread. When that happens, a man may have surgery or other heavy treatments that are not needed. Researchers are studying ways to improve the PSA test so that it catches only cancers that need treatment.
Clinical practice guidelines
Clinical practice guidelines may help guide decisions to screen:
- "the evidence is insufficient to recommend for or against routine screening for prostate cancer using prostate-specific antigen (PSA) testing or digital rectal examination (DRE). This is a grade I recommendation"
- American Cancer Society, in 2001, recommended:[8][9][10]
- "The PSA test and the DRE should be offered annually beginning at age 50 to men who have a life expectancy of at least 10 years. Men at high risk should begin testing at age 45. Information should be provided to patients about benefits and limitations of testing."
Interpreting the results of screening tests
Two clinical prediction rules help predict the probability of cancer based on the level of the prostate-specific antigen and other clinical findings.[11][12]
Evidence from trials
| Study name | Intervention | Outcome | Rates | Relative risk ratio | Comment | |
|---|---|---|---|---|---|---|
| Screening group | Control group | |||||
| PLCO:[13] 2009 |
Annual screening | Prostate cancer mortality | 2% | 1.7% | 1.22 | 52% of subjects in usual care group received screening outside of the study |
| ERSPC:[14] 2009 |
Screening every four years | Prostate cancer mortality | 0.3% | 0.4% | 0.80 | Number needed to treat = 1410. Rate of screening in the control group not stated, but estimated to be 20% prior to the trial. |
| Quebec:[15][16] 1999 |
Frequency not stated | Prostate cancer mortality | 0.1% | 0.5% | 0.26 | Did not use intention to treat analysis. |
| p < 0.05 | ||||||
References
- ↑ Yin M, Bastacky S, Chandran U, Becich MJ, Dhir R (2008). "Prevalence of incidental prostate cancer in the general population: a study of healthy organ donors". J. Urol. 179 (3): 892–5; discussion 895. DOI:10.1016/j.juro.2007.10.057. PMID 18207193. Research Blogging.
- ↑ Walsh PC, DeWeese TL, Eisenberger MA (December 2007). "Clinical practice. Localized prostate cancer". N. Engl. J. Med. 357 (26): 2696–705. DOI:10.1056/NEJMcp0706784. PMID 18160689. Research Blogging.
- ↑ 3.0 3.1 Harnden P, Shelley MD, Coles B, Staffurth J, Mason MD (May 2007). "Should the Gleason grading system for prostate cancer be modified to account for high-grade tertiary components? A systematic review and meta-analysis". Lancet Oncol. 8 (5): 411–9. DOI:10.1016/S1470-2045(07)70136-5. PMID 17466898. Research Blogging.
- ↑ Timothy J. Wilt et al., “Systematic Review: The Comparative Effectiveness and Harms of Treatments for Clinically Localized Prostate Cancer,” Ann Intern Med (February 4, 2008): http://www.annals.org/cgi/content/full/0000605-200803180-00209v1.
- ↑ U.S. Preventive Services Task Force (2002). "Screening for prostate cancer: recommendation and rationale". Ann. Intern. Med. 137 (11): 915-6. PMID 12458992. [e]
- ↑ Harris R, Lohr KN (2002). "Screening for prostate cancer: an update of the evidence for the U.S. Preventive Services Task Force". Ann. Intern. Med. 137 (11): 917-29. PMID 12458993. [e]
- ↑ U.S. Preventive Services Task Force (December 2002)). Screening for Prostate Cancer. Retrieved on 2006-09-14.
- ↑ Smith RA, von Eschenbach AC, Wender R, et al (2001). "American Cancer Society guidelines for the early detection of cancer: update of early detection guidelines for prostate, colorectal, and endometrial cancers. Also: update 2001--testing for early lung cancer detection". CA: a cancer journal for clinicians 51 (1): 38-75; quiz 77-80. PMID 11577479. [e]
- ↑ National Guideline Clearinghouse. Recommendations from the American Cancer Society Workshop on Early Prostate Cancer Detection. Retrieved on 2006-09-14.
- ↑ American Cancer Society. What the American Cancer Society Recommends. Retrieved on 2007-01-16.
- ↑ Nam RK, Toi A, Klotz LH, et al (2007). "Assessing individual risk for prostate cancer". J. Clin. Oncol. 25 (24): 3582–8. DOI:10.1200/JCO.2007.10.6450. PMID 17704405. Research Blogging.
- ↑ Thompson IM, Ankerst DP, Chi C, et al (2006). "Assessing prostate cancer risk: results from the Prostate Cancer Prevention Trial". J. Natl. Cancer Inst. 98 (8): 529–34. DOI:10.1093/jnci/djj131. PMID 16622122. Research Blogging. Online calculator
- ↑ 13.0 13.1 Andriole, Gerald L.; Robert L. Grubb, Saundra S. Buys, David Chia, Timothy R. Church, Mona N. Fouad, Edward P. Gelmann, Paul A. Kvale, Douglas J. Reding, Joel L. Weissfeld, Lance A. Yokochi, E. David Crawford, Barbara O'Brien, Jonathan D. Clapp, Joshua M. Rathmell, Thomas L. Riley, Richard B. Hayes, Barnett S. Kramer, Grant Izmirlian, Anthony B. Miller, Paul F. Pinsky, Philip C. Prorok, John K. Gohagan, Christine D. Berg, the PLCO Project Team (2009-03-18). "Mortality Results from a Randomized Prostate-Cancer Screening Trial". N Engl J Med: NEJMoa0810696. DOI:10.1056/NEJMoa0810696. Retrieved on 2009-03-19. Research Blogging.
- ↑ 14.0 14.1 Schroder, Fritz H.; Jonas Hugosson, Monique J. Roobol, Teuvo L.J. Tammela, Stefano Ciatto, Vera Nelen, Maciej Kwiatkowski, Marcos Lujan, Hans Lilja, Marco Zappa, Louis J. Denis, Franz Recker, Antonio Berenguer, Liisa Maattanen, Chris H. Bangma, Gunnar Aus, Arnauld Villers, Xavier Rebillard, Theodorus van der Kwast, Bert G. Blijenberg, Sue M. Moss, Harry J. de Koning, Anssi Auvinen, the ERSPC Investigators (2009-03-18). "Screening and Prostate-Cancer Mortality in a Randomized European Study". N Engl J Med: NEJMoa0810084. DOI:10.1056/NEJMoa0810084. Retrieved on 2009-03-19. Research Blogging.
- ↑ 15.0 15.1 Labrie F, Candas B, Dupont A, et al (February 1999). "Screening decreases prostate cancer death: first analysis of the 1988 Quebec prospective randomized controlled trial". Prostate 38 (2): 83–91. PMID 9973093. [e]
- ↑ 16.0 16.1 Labrie F, Candas B, Cusan L, et al (May 2004). "Screening decreases prostate cancer mortality: 11-year follow-up of the 1988 Quebec prospective randomized controlled trial". Prostate 59 (3): 311–8. DOI:10.1002/pros.20017. PMID 15042607. Research Blogging.