GP practices who order more chest X-rays have fewer patients with cancers diagnosed at a late stage, researchers have found.
It builds on a previous study which identified large variation in how frequently practices ordered chest X-rays that could not be explained by factors such smoking prevalence, deprivation or other staff and patient demographics.
But this is the first study to show that the variation is associated with different outcomes, the researchers noted in the British Journal of General Practice.
The analysis also found that patients at practices with higher use of chest X-ray have slightly better survival.
With only half of patients diagnosed with lung cancer being eligible for screening, the findings support the use of chest X-ray in improving early detection of the disease, they concluded.
The study looked at records for 192,631 patients diagnosed with lung cancer across more than 7,400 GP practices in England between 2014 and 2018.
Practices in the top fifth of chest X-ray testing had 23% fewer cancers diagnosed at stage 3 or 4, the analysis funded by Cancer Research UK found.
There was also a small improvement in one and five-year survival for lung cancer patients between the practices that most frequently sent patients for chest X-ray compared to those who used the test the least.
Although an observational study, the team said the analysis was done as rigorously as possible.
It suggests that increasing use of chest X-ray by GPs for symptomatic patients, particularly by focusing on practices that use the test infrequently, could improve lung cancer outcomes.
Dr Stephen Bradley, a GP in Leeds and a senior clinical lecturer at the University of Sheffield said their previous work showed a lot of the variation between practices in their use of chest X-rays which seemed to be down to practice culture.
Their latest research shows that the difference ‘does seem to matter’, he added.
It could be that some GPs had beliefs about how accurate a test chest X-ray is as well as exposure to radiation but in reality, it is a relatively cheap non-invasive test, that is quick to perform and interpret compared with CT.
But it is also difficult for practices to assess how they compare to other practices on ordering chest X-rays because the data is not freely available, he added.
‘Practically speaking this does give us a bit of a steer in recognising that chest X-ray is useful.’
He added that GPs and other practice staff needed to keep an open mind when patients are presenting with potential symptoms of lung cancer even if they are consulting for another reason.
‘It’s just about taking that opportunity when patients present to us. They might mention about coughing or weight loss.’
Even with screening only half of lung cancer patients would be eligible and only half of those eligible take up the offer, he added.
‘It is still important we pick up cases of lung cancer in general practice,’ he said.
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That is interesting. I understand the investigation of choice for SUSPICIOUS symptoms is not CXR but HRCT chest.
Which makes this a more complex observation than it first seems.
Do practices that request more CXRs also request more HRCTs?
And does outcome correlate with those too?
Researchers think they have excluded any other patient, staff and practice location factors, so it would be wonderful to have some insight fromn pratices at the two ends of sepctrum, as to how they think they differ in CXR use?