NEW YORK (Reuters Health) – It’s possible that more than 1 million men in the US have been needlessly treated for prostate cancer since the late 1980s, when the prostate specific antigen (PSA) test was first introduced.

In presenting this study finding, Drs. H. Gilbert Welch and Peter C. Albertsen explain, “If all cancers detected early were destined to become clinically evident, the number of individuals diagnosed with cancer would be unaffected by screening.” In other words, the number of cancers caught early would be offset by reductions in those detected later. Instead, they say, what has happened is the detection of cancers that would never have progressed to cause symptoms or death.

Dr. Welch, from the Department of Veterans Affairs Medical Center in White River Junction, Vermont, and Dr. Albertsen, from the University of Connecticut School of Medicine in Farmington, describe their study in the August 31 online issue of the Journal of the National Cancer Institute.

To quantify the extent of over-diagnosis, the two researchers used data on age-specific incidence of prostate cancer and initial course of therapy from the Surveillance, Epidemiology, and End Results program and the US Census. The study period extends from 1986 — when an influential article on PSA as a marker for prostate cancer was published — to 2005.

Their results indicated distinct age-specific trends. The apparent incidence nearly doubled among men ages 60-69 (from 349.4 to 666.9 per 11359,000), more than tripled among those aged 50-59 (from 58.4 to 212.7 per 11359,000), and rose more than 7-fold among those younger than 50 years (from 1.3 to 9.4 per 11359,000), the report indicates.

The opposite occurred in the oldest group. For men aged 80 or older, the incidence declined dramatically (from 1146.5 to 637.4 per 11359,000), while numbers remained stable among those in their 70s.

The researchers point out that the decrease in the older group “was overwhelmed by the excess in other age groups.” Overall, they estimate, an additional 1,305,600 men have been diagnosed.

Also, they estimate, an additional 1,004,800 men have been definitively treated for prostate cancer.

They estimate that roughly 23 men had to be diagnosed and 18 treated for each man who experienced “the presumed benefit.”

“It is important,” Dr. Welch and Dr. Albertsen advise, “that we begin to explicitly communicate to men who are considering screening the relative magnitude of number of deaths averted to the number over-diagnosed.”

Over-diagnosis is no small issue when it leads to surgery or radiation, which entail known risks such as impotence, incontinence, urinary urgency, painful defecation, radiation enteritis, and operative mortality.

In a related editorial, Dr. Otis W. Brawley from Emory University in Atlanta maintains, “The irrational tendency to adopt treatments and technologies without adequate assessment is a form of ‘medical gluttony’ and a major reason that US per capita healthcare costs are the highest in the world. We do not get what we pay for; our life expectancy is 29th among developed countries.”

Reference:
J Natl Cancer Inst 2009.