Lessons from NELSON study: implementation trials the next step in lung cancer screening

Lung cancer

By Mardi Chapman

18 Aug 2020

Countries should be building their national lung cancer screening programs given the clear cut evidence that screening is effective, that the benefits outweigh the harms, and that it can also be cost effective.

Speaking at ATS 2020 Virtual, Professor Harry de Koning said the next step was implementation trials in each country to answer remaining questions such as the relative safety of biennial versus annual screening in lower risk individuals after an initial baseline CT was negative.

Professor de Koning, chief investigator on the NELSON study published earlier this year in the NEJM, said individual countries might for example shape their programs by tweaking the age range of participants, pack years or smoking and years since smoking.

“But it’s not easy to say what we should do,” he said.

For example, the number of eligible people in Europe ranged from about 11.5 million if enrolling 60-80 years olds with a minimum of 40 pack-years or a maximum of 10 years since quitting smoking to almost 25 million if enrolling 60-80 years olds with a minimum of 25 pack-years and 25 years since quitting.

“We probably need personalised risk calculators to say at a certain cut off below that we should not invite them and above that, we probably should. But we do not have enough information yet whether it could be safe enough to do for instance two-yearly screening if your baseline CT scan is negative.”

He said a European implementation trial 4 IN the Lung Run planned to enrol 24,000 people will help identify the most effective and cost-efficient strategy.

Presenting some of the highlights from the Dutch-Belgian NELSON trial, Professor de Koning noted that as well as detecting more cancers in the screening group, an important finding was the “enormous stage shift” in lung cancers detected.

Stage IV lung cancers represented just 10% of cancers in the screened group compared to 46% of cancers detected in the usual care group while stage I cancers were 60% in the screened group compared to just 13% in the usual care group.

Lung cancer mortality at ten years follow-up was 2.50 per 1,000 person years in the screened group compared to 3.30 per 1,000 person-years in the usual care group – a lung cancer mortality rate ratio of 0.76.

The difference was evident after 1-2 years of follow-up, Professor de Koning said.

The study found no significant differences in other causes of death between the screened and control groups. Larger numbers of participants were required to demonstrate any statistically significant impact on all cause mortality.

Professor de Koning said the NELSON study was powered for high risk males who made up about 85% of the participants.

“Very importantly, our trial had a small amount of females included but a huge effect – 0.41 [at 8 years], 0.52 [at nine years] and 0.67 [at ten year follow-up] lung cancer mortality rate ratio.”

USPSTF recommendations to change

In the same ATS 2020 session on lung cancer screening, Dr Michael Barry from Harvard Medical School said the NELSON study had provided evidence for proposed changes to the US Preventive Services Task Force recommendations.

He said compared to the USPSTF’s 2013 recommendations the new draft proposed dropping the start age for screening from 55 to 50 years and reducing the pack-year smoking threshold from 30 to 20 years.

“A program that annually screens people ages 50 to 80 years who have at least a 20 pack-year smoking history and currently smoke or have quit within the past 15 years would reduce overall lung cancer mortality by 13.0%,” he said.

Screening would avert about 500 lung cancer deaths and lead to 7,000 life-years gained per 100,000 persons.

Dr Barry said screening for lung cancer in people with lighter smoking histories and at a  younger starting age might also help mitigate racial and gender disparities in screening eligibility.

He noted that all people enrolled in a screening program should receive smoking cessation interventions as quitting was still the best way to reduce lung cancer deaths.

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