Luján M, Páez Á, Angulo J C, Granados R, Nevado M, Torres G M, Berenguer A
Unidad de Urología, Hospital Universitario Infanta Cristina, Universidad Complutense de Madrid, Madrid, España.
Servicio de Urología. Hospital Universitario de Fuenlabrada, Universidad Rey Juan Carlos, Madrid, España.
Actas Urol Esp. 2016 Apr;40(3):164-72. doi: 10.1016/j.acuro.2015.10.005. Epub 2015 Nov 24.
Recently, the European Randomized Study of Screening for Prostate Cancer achieved a reduction in prostate cancer mortality by measuring serum prostate-specific antigen (PSA) levels. These results were not reproduced in the Spanish arm of European Randomized Study of Screening for Prostate Cancer. PSA contamination (opportunistic measurements outside the study) could decrease the study's contrasting power if performed in the control arm. We have calculated the long-term rate of PSA contamination and its effect on performing prostate biopsy and detecting cancer.
A total of 4,276 men were randomised (2,415 to the screening arm, 1,861 to the control arm) in the Spanish section of the European Randomized Study of Screening for Prostate Cancer. PSA measurements were not scheduled in the control arm. Sextant prostate biopsy was indicated if PSA levels were ≥3 ng/mL. All PSA readings performed outside the study were labelled as "PSA contamination". We calculated the rates of PSA contamination, biopsy implementation and cancer detection.
The median age and follow-up time were 57 and 15.1 years, respectively. A total of 2,511 men underwent at least one PSA reading outside the study. PSA contamination at 5, 10 and 15 years was 22.0%, 47.1% and 66.3% in the screening arm, respectively, and 20.8%, 43.2% and 58.6% in the control arm, respectively (P<.0001). The biopsy rate at 5, 10 and 15 years was 19.3%, 22.6% and 24.1% (screening), respectively, and 1.0%, 3.6% and 7.1% (control), respectively (P<.0001). The PC detection rate was 6.7% (screening) and 4.3% (control; P=.0006).
Although the cumulative PSA contamination was pronounced in the 2 study arms, the rate of prostate biopsies was low in the control arm. We therefore believe that the effect of PSA contamination on the study's statistical power should be limited.
最近，欧洲前列腺癌筛查随机研究通过检测血清前列腺特异性抗原（PSA）水平降低了前列腺癌死亡率。但这些结果在欧洲前列腺癌筛查随机研究的西班牙分支中并未重现。如果在对照组中进行PSA污染检测（研究之外的机会性检测），可能会降低研究的对比效力。我们计算了PSA污染的长期发生率及其对进行前列腺活检和检测癌症的影响。
在欧洲前列腺癌筛查随机研究的西班牙部分，共有4276名男性被随机分组（2415名进入筛查组，1861名进入对照组）。对照组未安排PSA检测。如果PSA水平≥3 ng/mL，则进行六分区前列腺活检。所有在研究之外进行的PSA检测读数都被标记为“PSA污染”。我们计算了PSA污染率、活检实施率和癌症检测率。
中位年龄和随访时间分别为57岁和15.1年。共有2511名男性在研究之外至少进行了一次PSA检测。筛查组在5年、10年和15年时的PSA污染率分别为22.0%、47.1%和66.3%，对照组分别为20.8%、43.2%和58.6%（P<0.0001）。筛查组在5年、10年和15年时的活检率分别为19.3%、22.6%和24.1%，对照组分别为1.0%、3.6%和7.1%（P<0.0001）。前列腺癌检测率为6.7%（筛查组）和4.3%（对照组；P=0.0006）。
尽管两个研究组中累积的PSA污染情况较为明显，但对照组的前列腺活检率较低。因此，我们认为PSA污染对研究统计效力的影响应该是有限的。
