Dr Tracy Leong
The evidence of lung cancer screening benefit is now so strong that it will inevitably come to Australia, the only question being how it is implemented, according to local experts.
Presentations at the recent ERS 2020 virtual congress showed that the discussion around lung cancer screening has moved on from the major efficacy trials such as NLST and NELSON to focus on the issues of implementation and cost, says Dr Tracy Leong, Director of Bronchoscopy, Department of Respiratory and Sleep Medicine, Austin Health.
Speaking on a limbic webinar about the highlights from ERS, she said that with meta-analysis now showing a 20% reduction in lung cancer mortality with screening, many of the sessions at ERS were addressing issues such as eligibility for screening, false positives and practical questions such as whether there are enough radiologists and respiratory physician to manage the many nodules found on imaging.
Dr Leong said it was encouraging to see progress in areas such as the use of risk tools for eligibility rather than just relying on age and smoking history. And advances in CT technology mean that radiation doses have been reduced to the equivalent of three chest x-rays she noted.
Australia now awaits the results of the ILST study which has local sites, in about two year’s time, and also the outcome of a Cancer Australia inquiry into implementation of cancer screening ordered by the Minister for Health.
“So I think that screening in Australia is coming, it’s just a matter of deciding what’s the best form to put that in,” she said.
In the meantime, it is important to embrace minimally invasive and precise ways to sample the nodules that will be found on lung cancer screening, particularly as studies show more than a half will be in the peripheral lung.
“Nodules are becoming a hot topic – they are to us what the polyp is to the gastroenterologist, and they are an increasing problem,” she said.
Since these nodules are small – less than 20mm – there is a need to look at micro-sampling techniques with high precision that can obtain a high tissue volume sufficient for diagnostic testing.
Dr Leong noted that standard bronchoscopy under fluoroscopic guidance is a relatively imprecise technique – “This is accepted as like the flip of a coin – the chances of you hitting your mark and getting a diagnosis are less than 50%,” she said.
Newer techniques such as 3D image guidance with conebeam CT have shown encouraging yields of more than 80%, while robot bronchoscopy has recently been shown by Dr David Fielding and colleagues in Brisbane to have a diagnostic yield for small lesion of 88%.
And techniques to increase sample volume could include transbronchial cryobiopsy as currently used in interstitial lung disease, said Dr Leong, although the pneumothorax rate of around 6% was an issue.
“We are doing a few of these things in Australia,” said Dr Leong, highlighting the work of Dr Daniel Steinfort at the Royal Melbourne Hospital in areas such as video bronchoscopy and electromagnetic navigation and conebeam CT.
“But really looking forward what is on the horizon is using a lot of these techniques, particularly the cryoprobe to be therapeutic and not just diagnostic. Looking at this as an augmentor of the immune response, as part of immunotherapy” she said.