可根据PSA水平决定40多岁男性的前列腺癌筛查频率

亚特兰大(EGMN)——梅奥医院的Christopher Weight博士在美国泌尿学会(AUS)年会上报告，前列腺特异性抗原(PSA)水平低的40~49岁男性，可以安全地推迟至10~15年后再复查。然而，基线PSA水平较高的年轻男性在此期间发生前列腺癌的几率增加1倍，很可能应当定期筛查PSA。

这项纳入268名40多岁男性的前瞻性研究显示，基线PSA≤1.0 ng/ml的男性无1人在10年内发生高危疾病，15年内也仅有3%发病。研究者指出，该研究结果提供了一种有效的年轻人群危险分层方法，可以减少不必要的检查及其后续效应。

Weight博士采用了奥姆斯特德县队列的数据。自1990年以来，该县大多数居民在梅奥医院及其附属中心接受医疗服务。本次分析纳入了268名男性，他们均在40多岁时进行了基线PSA检查(中位年龄45岁)，并接受了经直肠超声和直肠指诊。目前这些受试者已接受了多达20年的随访，中位随访16年。在这一队列中，192人的基线PSA水平≤1.0 ng/ml，76人＞1.0 ng/ml。两组受试者在家族史或直肠检查结果方面均无显著差异。

结果显示，在整个后续随访期间，基线PSA水平较低的男性发生PSA超过年龄别切点的风险，显著低于基线PSA水平较高者(10% vs. 50%)。截至随访结束时，低PSA组共发生6例前列腺癌，且均为低危疾病。相当于发病率为1.6例/1000患者·年，平均在15年后被诊断。高PSA组发生前列腺癌的人数增加1倍以上(12例)。在这些患者中，10例为低危疾病，2例为高危疾病。相当于发病率为8例/1000患者·年，平均在10年后被诊断。

Weight博士指出，基线检测值是15年结局的良好预测指标。以基线水平1.0 ng/ml作为切点，预测前列腺癌发生的敏感性为67%，特异性为74%。如果将切点降至0.7 ng/ml，敏感性增至83%，特异性则降至46%。“我们承认的确存在过度诊断和过度治疗的问题，但如果完全抛弃PSA检查也是危险的。早期检测PSA可以帮助我们确定哪些男性可以安全地推迟再次检查，哪些人则能从更频繁的检查中获益。”

主持本次吹风会的芝加哥大学医学中心泌尿结局与转化研究部主任Scott Eggener博士表示，上述结果表明，早期单次PSA检查结果可能有助于指导患者随访。他指出：“任何检查都是为了确定最可能获益的人群和宜限制筛查以减少潜在危害的人群。如果一名男青年的PSA水平很低，我们就可以放心地建议他多年后再复查，如果PSA水平高，可能就需要更频繁地随访。”

Weight博士和Eggener博士均报告无相关利益冲突。


BY MICHELE G. SULLIVAN
Elsevier Global Medical News
Breaking News
ATLANTA (EGMN) – Men in their 40s with a low prostate specific antigen can probably safely delay additional testing for 10-15 years.
Young men with a higher baseline level, however, are twice as likely to develop prostate cancer over the same time period and should probably have their PSA tested at regular intervals, Dr. Christopher Weight said at the annual meeting of the American Urologic Association.
His prospective study of 268 men in their 40s showed that none of the men with a baseline PSA of 1.0 ng/mL or less developed high-risk disease by 10 years and only 3% developed it by 15 years. The findings could provide an effective way to risk-stratify young populations, reducing unnecessary testing and the consequences that sometimes follow it, he said.

“We have to admit that we overdiagnose and overtreat men,” Dr. Weight said at a press briefing. “But there is danger in completely throwing out the PSA test. Testing men early can help us identify those who can safely delay additional testing and those who will benefit from more frequent tests.”

Dr. Weight, a urology oncology fellow at the Mayo Clinic, Rochester, Minnesota, turned to the Olmsted County cohort for the study data. Since 1990, most of the residents in the county have received their medical care through the Mayo Clinic and its affiliate centers. A linked health records database provides information for long-term population-based studies.

His analysis included 268 men, all of whom had a baseline PSA drawn sometime during their 40s (median age 45 years). The men also had a transrectal ultrasound and digital rectal exam. They have been followed now for up to 20 years, with a median time of 16 years.

Among the cohort, 192 had a baseline PSA of 1.0 ng/mL or lower and 76 had a level of more than 1.0 ng/mL. There were no significant between-group differences in either family history or the results of the rectal exam.

Over the full follow-up period, men with the lower PSA level had a significantly lower risk of exceeding the age-specific cut points for PSA than did men with the higher levels (10% vs. 50%).

By the end of the follow-up period, there were six incident cases of prostate cancer in the low-PSA group, all of which were low-risk disease. This translated to an incidence rate of 1.6 per 1,000 patient/ years, with a mean of 15 years until diagnosis.

Twice as many men in the high-PSA group developed prostate cancer (12). Of these cases, 10 were low-risk disease and 2 high-risk. This translated into a rate of 8/1,000 patient-years, with a mean of 10 years to diagnosis.

The baseline measurement was fairly predictive of 15-year outcomes, Dr. Weight said. A cutoff of 1.0 ng/mL at the initial test had a sensitivity of 67% and a specificity of 74% for predicting the occurrence of prostate cancer. Changing the cutoff to 0.7 ng/mL on the initial test resulted in a sensitivity of 83% and a specificity of 46%

The results show that this single, early PSA level may be helpful in counseling patients about follow-up, said Dr. Scott Eggener, who moderated the briefing.

“The goals of any test are to identify the cohort of people most likely to benefit, and those people in whom screening can be limited to minimize the potential harms of the test,” said Dr. Eggener, director of urology outcomes and translational research at the University of Chicago Medical Center. “If a young man has a very low PSA, we can feel comfortable in recommending that he have another test in several years, somewhat like what's done with a screening colonoscopy. If the level is higher, this patient probably needs to be followed more frequently.”

Neither Dr. Weight nor Dr. Eggener had any financial disclosures.