PSA検診について自分なりの考えをまとめたことがある。
PSA検診の是非について色々議論されているが、自分なりの結論は以下の通りである。
PSA検診を受けなければ前立腺がんの早期発見は極めて困難になる。
以下のことを条件に、これからもPSA検診を進めていきたい。
１：PSA検診の普及活動と同時に、検診を受けることの利点、欠点のさらなる啓蒙活動
２：PSAが異常であった場合の検査（生検）方法のさらなる侵襲低減化
３：前立腺がんと診断された場合の各種治療オプションの利点、欠点の詳しい提示。
４：前立腺がん治療のさらなる低侵襲化
５：無治療経過観察が可能な群を同定する方法を開発する努力
ところが今秋、The US Preventive Services Task Force （USPSTF）が
PSA検診は推奨できないとの声明を発表した。
USPSTFは以前より75歳以上の男性でのPSA検診は勧められないとしていたが、
今回は全年齢でのPSA検診を勧めないとした。
米国では十分にPSA検診が普及しており、実際問題、前立腺癌の死亡率は低下してきている。
日本ではまだ十分にPSA検診が普及しておらず、前立腺癌の死亡率は年々増加している。
今回のUSPSTFの声明により我が国のPSA検診普及が遅れれば、
前立腺癌死の増加は今後も食い止められないのではないだろうか？
Study Highlights
Researchers used common medical databases to address the following 4 questions:
Does PSA-based screening decrease prostate cancer–specific or all-cause mortality risk?
What are the harms of PSA-based screening for prostate cancer?
What are the benefits of treatment of early-stage or screening-detected prostate cancer?
What are the harms of treatment of early-stage or screening-detected prostate cancer?
Specifically, researchers sought randomized trials of screening for prostate cancer among asymptomatic or minimally symptomatic men. They also included randomized trials and cohort studies that examined radical prostatectomy or radiation therapy for the treatment of prostate cancer.
They identified 2 fair-quality and 3 poor-quality randomized trials of PSA-based screening as well as 2 randomized controlled studies describing the benefits and harms of prostate cancer treatments. 9 cohort studies provided data regarding the benefits of prostate cancer treatment, and 14 cohort studies reported harms of treatment.
The most important studies contributing to the study conclusions regarding prostate cancer screening were the US Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial and the European Randomized Study of Screening for Prostate Cancer (ERSPC).
After 7 years of follow-up in the PLCO trial, screening was associated with an increased incidence of prostate cancer but no significant effect on prostate cancer–specific or overall mortality. The PLCO trial was limited by contamination of the study cohort, with up to 52% of the men assigned to usual care receiving a PSA test at some point.
The ERSPC also demonstrated a higher incidence of prostate cancer associated with screening and no significant overall effect of screening on the risk for prostate cancer–specific mortality. However, screening was effective in reducing the risk for prostate cancer–specific mortality in a prespecified analysis of men between the ages of 55 and 69 years.
3 poor-quality trials failed to find a difference between prostate cancer screening and control groups in the risk for prostate cancer–specific mortality.
The risk for a false-positive test for cancer based on the PSA result was between 12% and 13%.
Serious infections or urinary retention occurred after 0.5% to 1.0% of prostate biopsies. No studies addressed possible psychological harms associated with prostate cancer screening.
One good-quality trial with 13 years of follow-up demonstrated that prostatectomy for localized prostate cancer reduced the risk for prostate cancer–specific mortality compared with watchful waiting. However, this benefit appeared limited to men younger than 65 years.
Cohort studies demonstrated that both prostatectomy and radiation therapy reduced the risks for prostate cancer–specific mortality and overall mortality.
Treating 5 men with prostatectomy resulted in 1 additional case of urinary incontinence. The number needed to harm for erectile dysfunction associated with prostatectomy is 3.
Radiation therapy is less associated with urinary incontinence, but it still has a number needed to harm of 7 to cause erectile dysfunction. Radiation therapy also appears to increase the risk for bowel injury, particularly in the short term.
Prostatectomy was associated with rates of perioperative death of approximately 0.5% and perioperative cardiovascular events of 0.6% to 3.0%.
On the basis of these data, draft recommendations from the USPSTF counsel against PSA-based screening for prostate cancer. This is a grade D recommendation, meaning that there is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits.
From Medscape Education Clinical Briefs
Intern Med. Published online October 7, 2011.