前立腺癌のスクリーニングを年に1度行っても、前立腺癌による死亡を減少させることはない。Washington University of Medicineの研究者らは、76,000名以上の男性を対象にした研究結果を『Journal of the National Cancer Institute』1月6日号に発表した。
Contact: Caroline Arbanas
Washington University School of Medicine
Mass prostate cancer screening doesn't reduce deaths
There's new evidence that annual prostate cancer screening does not reduce deaths from the disease, even among men in their 50s and 60s and those with underlying health conditions, according to new research led by Washington University School of Medicine in St. Louis.
A longer follow-up of more than 76,000 men in a major U.S. study shows that six years of aggressive, annual screening for prostate cancer led to more diagnoses of tumors but not to fewer deaths from the disease.
The updated results of the Prostate, Lung, Cancer, Colorectal and Ovarian (PLCO) Cancer Screening Trial will be published online Jan. 6 in the Journal of the National Cancer Institute.
"The data confirm that for most men, it is not necessary to be screened annually for prostate cancer," says the study's lead author and principal investigator Gerald Andriole, MD, chief urologic surgeon at the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. "A large majority of the cancers we found are slow-growing tumors that are unlikely to be deadly."
The PLCO study involved men ages 55 to 74, who were randomly assigned to receive either annual PSA tests for six years and digital rectal exams for four years or "routine care," meaning they had the screening tests only if their physicians recommended them.
The new research updates an earlier report of the data published in 2009 in the New England Journal of Medicine. At that time, when nearly all men had been followed for seven years, Andriole and his colleagues did not find a mortality benefit from prostate cancer screening.
But because so few men in the study had died from any causes, the researchers said then that it would be premature to make broad generalizations about whether men should continue to be screened. However, they did recommend against prostate cancer screening for men with a life expectancy of seven to 10 years or less.
"Now, based on our updated results with nearly all men followed for 10 years and more than half for 13 years, we are learning that only the youngest men — those with the longest life expectancy — are apt to benefit from screening. We need to modify our current practices and stop screening elderly men and those with a limited life expectancy," says Andriole, who also is the Robert K. Royce Distinguished Professor. "Instead, we need to take a more targeted approach and selectively screen men who are young and healthy and particularly those at high risk for prostate cancer, including African-Americans and those with a family history of the disease."
Andriole recommends that men get a baseline PSA test in their early 40s because recent studies have indicated that elevated levels at that age can predict the risk of prostate cancer in later years. Men in their 40s with low PSA levels are very unlikely to develop lethal prostate cancer and could potentially avoid additional testing.
The researchers detected 12 percent more prostate tumors among men screened annually compared to those who received routine care (4,250 tumors in the screening arm vs. 3,815 tumors in the control arm).
But deaths from prostate cancer did not differ significantly between the groups. There were 158 deaths from prostate cancer in the screening group and 145 deaths in the routine-care group.
Annual screening tests also did not reduce deaths from prostate cancer among men in their 50s and 60s, as the researchers had hoped.
In addition, men diagnosed with prostate cancer who also had a history of heart attacks, strokes, diabetes, cancer or lung and liver disease were far more likely to die from causes other than prostate cancer – a finding that suggests that screening often finds tumors that are not likely to cause harm.
"Mass screening of all men on the basis of age alone is not the way to go, but screening can still be useful in select men," says Andriole, who acknowledges that widespread testing has lead many men with slow-growing tumors to be over-diagnosed and over-treated with surgery or radiation therapy, the possible side effects of which include incontinence and impotence. "We have to take a more nuanced approach to determine which men should be screened with PSA in the first place, how frequently they should be tested, the PSA level at which they should be biopsied and whether their cancer warrants aggressive therapy."
The study comes just months after a draft recommendation by the U.S. Preventive Services Task Force calling for an end to routine PSA testing for healthy men age 50 and older because of concerns that the test does not save lives and, when positive, often leads to invasive biopsies and aggressive treatments.
The researchers will continue to follow patients in the PLCO study for up to 15 years after they enrolled and evaluate the effects of prostate cancer screening on mortality.
Andriole GL, Crawford ED, Grubb RL, Prorok PC et al. Prostate cancer screening in the randomized prostate, lung, colorectal and ovarian cancer screening trial: mortality results after 13 years of follow-up. Journal of the National Cancer Institute, published online Jan. 6, 2012.
The research is funded by the National Cancer Institute at the National Institutes of Health (NIH).
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.