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Diagnosing Lung Cancer: Chest x-rays, CT scans and the role of Primary Care

Thursday, February 1, 2024

In this article we talk to Dr Stephen Bradley, GP and NIHR Academic Clinical Lecturer at York Street Practice and University of Leeds. Stephen shares with us the challenges of diagnosing lung cancer and how the use of chest x-rays and CT scans offers potential benefits. He also elaborates on what the role of primary care should be in the national lung cancer screening programme.


Why is focusing on early diagnosis of symptomatic lung cancer in primary care important? What are some of the benefits to patients?

Quite appropriately a lot of attention has been paid to implementing screening with low dose computed tomography (LDCT) for patients who don’t necessarily have symptoms of lung cancer, but many patients will still have their lung cancer detected because of symptoms, rather than screening. This is because screening focuses on those at highest risk because of smoking, because cancers can develop between screening rounds and because large proportions of patients do not participate in screening.

Traditionally people have sometimes speculated that by the time lung cancer symptoms develop its “too late” for patients to benefit. We know this isn’t true, not least because we now have much better treatments. Lung cancer outcomes have improved and this is probably partly because we now do a better job of identifying lung cancer symptoms earlier. For example, haemoptysis (coughing blood) used to be a fairly common symptom of lung cancer, nowadays less than 5% of cases present in this way, probably because GPs and patients take action before this arises.

But there’s still a lot of room for improvement.  For example, a recent study in Thorax by Dr Monica Koo and colleagues has shown that patients with symptoms are commonly not receiving imaging within the recommended two weeks. An excellent accompanying editorial by Dr Katherine Hickman (primary care respiratory society) explores some of the issues arising from that research.

How can chest X-rays be used in part of this early diagnosis? What are any benefits/shortfalls of their use?

Chest x-ray is recommended by NICE for a wide range of symptoms and presentations, including some that might not be immediately obvious, like raised platelet count on a full blood count. The guidelines advise chest x-ray is the first test for all symptoms apart from those with haemoptysis, or for whom there is a particularly high degree of concern. Chest x-ray is a useful test as it has a low dose of radiation, it is relatively cheap and is widely accessible to GPs. The main drawback is that it potentially misses around 20% of lung cancers.

The challenge of diagnosing lung cancer for GPs is that the most symptoms of the disease, like cough, are extremely common in general.

The challenge of diagnosing lung cancer for GPs is that the most symptoms of the disease, like cough, are extremely common in general. This means that the chance of any one patient’s cough being caused by a cancer is generally very low (well under 1%). We also know that for almost all symptoms the chance of having lung cancer despite a normal chest x-ray is very low indeed. The one exception is haemoptysis – the risk of which despite a negative chest x-ray remains around 3%, which really vindicates NICE’s guidance that these patients should be have further investigation regardless of chest x-ray findings (unless a benign cause is identified, like dental bleeding).

Chest x-ray’s strengths mean it can be used in very high numbers (around 1.8 million chest x-rays are requested from general practice in England per year) in patients who individually have quite low levels of risk because of common symptoms. GPs and patients should be aware though that chest x-ray is by no means perfect and that people who have had a normal chest x-ray might still need a CT if their symptoms persist. This is very challenging for GPs and research will hopefully soon be underway to find out if GPs should use CT instead of chest x-ray as the first line test for more patients. Why is direct access to CT scans an important part of early diagnosis?

Direct access allows GPs to arrange CT for patients they are particularly worried about. The NHS announced in 2022 that all English GPs would be given direct access to CT. Some guidance has been issued as to which patients GPs should consider for CT, but there is probably room to improve this. While GPs now officially have direct access to CT, it’s not clear how much this policy has changed things on the ground since the numbers of CTs being requested from primary care do not seem to have increased substantially following the announcement.   

What should the role of primary care be in the national lung cancer screening programme?

General Practices have reach into many communities, and can often connect with our most underserved citizens in a unique way.

The importance of primary care to the success of the new national lung cancer screening programme has not been fully appreciated.  For the programme to bring optimal benefit, we need as many eligible patients as possible to participate. General Practices have reach into many communities, and can often connect with our most underserved citizens in a unique way. When patients receive invitations to participate in the screening programme many people will bring these to their GP to ask whether they should take part.

Although GPs working in areas in England where we’ve had pilot lung cancer screening programmes (‘lung health check’) will be familiar with the principles, my sense is that for many GPs awareness that there is a national programme on the way, and the importance of this, is low. Many GPs and their teams routinely contact patients who have missed screening for other cancer programmes (e.g. cervical and bowel) to encourage them to participate. We need to harness this support for the lung cancer screening programme also.