Overdiagnosis of Prostate Cancer Widespread, Study Finds
Article date: August 31, 2009
By Rebecca V. Snowden
Over the last 20 years, the number of men who have been diagnosed with prostate cancer has increased, due in large part to widespread screening using the prostate-specific antigen (PSA) blood test. A new study published in the Journal of the National Cancer Institute shows many of those men – more than a million, by the researchers' calculations – may not have benefitted from that diagnosis.
That news conflicts with what most people think about cancer – that it should be caught early whenever possible. While that is true for many cancers, researchers still don't know for sure whether prostate cancer screening saves lives. Results from 2 eagerly-anticipated trials that came out earlier this year – one American, one European – didn't find a large benefit from screening, although the final results will not be available for several years.
Difficulty determining who should be treated
One result of screening is that a lot of men may be getting diagnosed with and treated for prostate cancer when they don't need to be. Doctors call this overdiagnosis. Some prostate cancers grow very quickly, but many prostate cancers grow so slowly that they would never cause a man any problems at all, so treatment isn't really necessary.
Unfortunately, doctors can't be sure which men, once diagnosed, need treatment and which would be fine without any. And men who are told they have prostate cancer may have a hard time just doing nothing, even if the cancer is unlikely to cause them harm. Treatments for prostate cancer can have a lot of unpleasant side effects like incontinence and impotence that can really affect the quality of a man's life.
Clearly, some prostate cancers undoubtedly would cause problems at some point. For these men, screening and treatment is obviously helpful. But often there's no way to know what the outcome would have been in any particular man's case without treatment.
What this study found
Researchers H. Gilbert Welch, MD, MPH, of the White River Junction VA and Peter C. Albertsen, MD, of the University of Connecticut estimated the number of men diagnosed and treated for prostate cancer from 1986 to 2005. (PSA-testing was introduced in 1987.) They used data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program and the US Census.
Welch and Albertsen found that PSA screening led to more than 1 million additional men being diagnosed, many of whom were likely overtreated for prostate cancer. Numbers were especially high among younger men. The number of men aged 50-59 who were diagnosed tripled over the study period; the researchers saw a sevenfold increase in men under age 50.
The results highlight the urgent need to find a way to determine which prostate cancers are going to grow and spread and which aren't.
"We desperately need the ability to predict which patient has a localized cancer that is going to metastasize and cause suffering and death and which patient has a cancer that is destined to stay in the patient's prostate for the reminder of his life," writes Otis W. Brawley, MD, American Cancer Society Chief Medical Officer in an accompanying editorial.
The American Cancer Society does not recommend routine screening for prostate cancer at this time. Instead, men need to talk to their doctors about the pros and cons of screening, and then decide whether they want to be tested or not. Men at average risk should have this talk starting at age 50. Men at higher risk – African-American men and men who have a first-degree relative (father, brother, or son) diagnosed with prostate cancer at an early age (younger than age 65) -- should start earlier, at age 45.
For more information, see "Can Prostate Cancer Be Found Early?"
Citation: "Prostate Cancer Diagnosis and Treatment After the Introduction of Prostate-Specific Antigen Screening: 1986-2005." Published online August 31, 2009 in the Journal of the National Cancer Institute. Gilbert Welch, MD, MPH, White River Junction VA and Peter C. Albertsen, MD, University of Connecticut.
"Prostate Cancer Screening: Is This a Teachable Moment?" Published online August 31, 2009 in the Journal of the National Cancer Institute. Otis W. Brawley, MD, American Cancer Society Chief Medical Officer.
Reviewed by: Members of the ACS Medical Content Staff
ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases.
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