The practical problems of running a national lung cancer screening program are becoming apparent as Australian centres enter their second year of a five-year trial of low dose CT testing.
With a target of recruiting 2000 current and former smokers to undergo lung cancer screening, Australian centres have found themselves swamped with ineligible applicants while finding it difficult to reach the most at-risk individuals in rural areas.
Describing the progress of the International Lung Screening Trial (ILST), principal investigator Professor Kwun Fong a Brisbane thoracic physician, said centres in Perth, Brisbane, Melbourne and Sydney were about a quarter of the way to enrolling patients for the trial.
The trial’s target group is people aged 55 to 80 who have more than 30 pack-years smoking history. It seeks to evaluate the feasibility of an Australian model of lung cancer screening, and whether it can achieve the 20% reduction in mortality seen in the US National Lung Screening Trial (NLST).
Professor Fong said that recruitment to the trial had been done mostly through media and advertising campaigns, but about 1930 of the 3435 people who had volunteered were ineligible due to age or smoking status.
Trial co-ordinators from WA said they found it more efficient to use GP databases to identify people eligible for screening rather than sending out invitations based on age from electoral rolls.
Another issue identified in the ILST trial is whether there are sufficient radiologists to offer low dose CT screening to large numbers of people and capacity in the specialist medical workforce to provide follow up of results to people who have been screened.
“There aren’t enough thoracic physicians or oncologists to see them in tertiary care so we’ll probably have to work out how to do this with GPs,” said Professor Fong.
As well as implementation issues, the trial will also evaluate whether it is cost effective to screen for lung cancer. Estimates from the Queensland Lung Cancer Screening study showed that the average cost per patient was $3768.
However, mathematical modelling suggested that screening could cost $233,000 per quality adjusted life year (QALY) gained, putting it well outside the $50,000-per QALY acceptable threshold often quoted for cost effectiveness. The high cost of workup for false positive screening results was one of the main drivers for excess costs.
Professor Fong said a national lung cancer screening program would also have to manage public expectations about the effectiveness of tests and demand for screening, given that only high risk individuals would be eligible.
He noted that some private sector radiology providers are already offering opportunistic testing, and Silicon Valley companies are expected to offer more sophisticated screening based on gene markers of lung cancer .
And given the rapid pace of development of liquid biopsies and tumour DNA for lung cancer the low-dose CT screening model might be obsolete by the time the five year trial had been completed, he suggested.
“CT screening may be out of date already. Single modality screening is never going to achieve what we really want. Do we really need to be thinking of doing different combinations [of tests] instead of spending five years of doing a single modality?”