专家组反对低剂量CT用于联邦医疗保险患者肺癌筛查

美国联邦医疗保险证据开发和覆盖范围咨询委员会（MEDCAC）成员在4月30日会议上称，证据不足以支持应用低剂量计算机断层扫面（LDCT）对联邦医疗保险人群进行肺癌筛查。专家组特别指出，总体上，他们对联邦医疗保险人群LDCT肺癌筛查获益大于伤害的充分证据缺乏信心。

Rita Redberg博士 

联合健康保险（United Healthcare Medicare & Retirement）全国医学主任Curtis Mock博士称：“当我意识到我们的责任首先是不应伤害患者时，我认为将我们的预期结果外推至联邦医疗保险人群是不可能的。”联邦医疗保险和医疗补助服务中心（CMS）接受了两项正式请求，启动LDCT肺癌筛查全国覆盖分析。美国预防服务工作组（USPSTF）已将基于年龄和吸烟史的高危肺癌患者接受LDCT肺癌筛查列为B级推荐。Rita Redberg博士 

大多数专家对全国肺部筛查试验（NLST）中有关联邦医疗保险人群的数据并不满意。该研究纳入50,000余例无症状成人，年龄55~74岁。结果显示，接受LDCT筛查患者肺癌死亡率和全因死亡率分别下降16%和6.7% （N. Engl. J. Med. 2013;368:1980-91），每320例患者接受筛查可避免1例患者死于肺癌，每219例患者接受筛查可预防1例全因死亡患者。

然而，符合联邦医疗保险条件的患者（65~74岁）约占受试患者的25%，小于符合NLST入组标准人群占美国人口约36%的比例。

MEDCAC主席、加州大学旧金山分校医学教授Rita Redberg博士称：“我担心我们真的没有太多的联邦医疗保险患者数据，当然也没有75~80岁人群的数据，特别是NLST试验中有关该年龄组人群危害的数据。”她认为：“手术死亡率随年龄增大而增大， 早期出现的获益也会逐渐消失，因为对抗获益的死亡因素越来越多。”

专家组还指出，他们不能确信如果对联邦医疗保险人群实施LDCT（平均效应剂量为1.5 mSv）肺癌筛查，其危害程度能否达到最小化。

密歇根大学安娜堡分校内科教授Allan Fendrick博士说：“对于获益和伤害不清楚的人群，我担心伤害将成为筛查的障碍。”

同样，马里兰州贝塞斯达国防医科大学副教授Harry Burke博士称：“我认为较低的阳性预测值导致对筛查者的伤害，你能否权衡伤害与受益是一件非常困难的事情。”

最后，专家组认为，他们充分相信在临床试验之外对联邦医疗保险人群进行LDCT肺癌筛查缺少有临床意义的证据。

MEDCAC 副主席、康奈尔大学患者导向比较疗效研究项目主任Art Sedrakyan博士说： “我认为最重要的不足在于，所基于的全部数据，包括大规模NLST试验和其他试验的高质量文献，应该能够让我们充分相信某一部分人群在获益大于伤害方面优于另一部分人群。”

CMS在制定覆盖全国的LDCT肺癌筛查决策时将考虑专家组的意见，有关决策预计在11月中旬之前公布，并将有30天的征求公众意见时间。

 

By: REBECCA KERN, Oncology Practice Digital Network

AT A MEDCAC MEETING

Evidence is insufficient to support lung cancer screening with low-dose computed tomography in the Medicare population, members of the Medicare Evidence Development and Coverage Advisory Committee said at a meeting on April 30.

Specifically, the MEDCAC advisers said that, on average, they had low confidence there is adequate evidence that the benefits outweigh the harms of lung cancer screening with low-dose computed tomography (LDCT) in the Medicare population.

The Centers for Medicare & Medicaid Services accepted two formal requests to initiate a national coverage analysis on lung cancer screening with LDCT, which the U.S. Preventive Services Task Force gave a grade B recommendation for people at high risk for lung cancer based on age and smoking history.

"I think it’s almost impossible to extrapolate to the Medicare population the expected results that we would get when I feel it’s our obligation to first do no harm. I didn’t hear that the evidence is there to support benefit beyond harm," said Dr. Curtis Mock, national medical director of United Healthcare Medicare & Retirement.

 

Most of the MEDCAC advisers said that they were not satisfied by the Medicare-population data in the National Lung Screening Trial (NLST). That study of more than 50,000 asymptomatic adults, aged 55-74 years, showed a 16% reduction in lung cancer mortality and a 6.7% reduction in all-cause mortality when patients were screened using LDCT (N. Engl. J. Med. 2013;368:1980-91). One cancer death was averted for every 320 patients screened, and one death from all causes was prevented in every 219 patients screened.

But Medicare-eligible patients – those aged 65-74 years – represented about 25% of patients in the trial, less than the nearly 36% NLST-eligible in the U.S. population.

"I am concerned that we don’t really have a lot of data in the Medicare population, certainly not in the 75-80 [year-old age group], particularly on the harms in the age group that was included in NLST," said Dr. Rita Redberg, MEDCAC chair and professor of medicine at the University of California, San Francisco.

"Surgical mortality increases as one gets older, and the benefits of early detection tend to disappear as you get older because there are more competing causes of death," she said.

The MEDCAC advisers also noted that they were not confident that the harms of lung cancer screening with LDCT (average effective dose of 1.5 mSv) would be minimized if implemented in the Medicare population.

"The harm I worry about will be the intervention of this test on people for which we know nothing about the benefits and harms," said Dr. Allan Fendrick, professor in the department of internal medicine at the University of Michigan, Ann Arbor.

Similarly, Dr. Harry Burke, associate professor at the Uniformed Services University of the Health Sciences in Bethesda, Md., said, "I think the low positive predictive value drives harm. Whether you can balance that harm with the benefit is a very difficult business."

Lastly, the advisors said that they strongly believe there are clinically significant evidence gaps when using LDCT for lung cancer screening in the Medicare population outside a clinical trial.

"The most important gap that I see is based on totality of the data – both from this large NLST trial but also high-quality publications from other trials – to be able to come up with a cohort where we would have much higher confidence that the benefits outweigh the harms than other subgroups," said MEDCAC vice chair Dr. Art Sedrakyan, director of the Patient Centered Comparative Outcomes Research Program at Cornell University, New York.

CMS will take the expert panel’s recommendations into consideration as it develops its national coverage decision for lung cancer screening with LDCT, which it plans to issue by mid-November, followed by a 30-day public comment period.