Today, we’re speaking to Dr Steve Bradley, GP and Senior Clinical Lecturer based within the School of Medicine and Population Health at the University of Sheffield.

Title of paper: General practice chest X-ray rate is associated with earlier lung cancer diagnosis and reduced all-cause mortality: a retrospective observational study

Available at: https://doi.org/10.3399/BJGP.2024.0466

It is known that there is wide variation in the use of chest X-ray (CXR) by general practices, but previous studies have provided conflicting evidence as to whether greater utilisation of them leads to lung cancer being diagnosed at an earlier stage and improves survival. This observational study analysed data from the English national cancer registry on CXR rates for individual general practices, along with stage and survival outcomes; it found earlier stage at diagnosis and improved survival for patients diagnosed with cancer at practices that used the test more frequently. Increasing use of CXR by GPs for symptomatic patients, particularly by focusing on practices that use the test infrequently, could improve lung cancer outcomes.

Transcript

This transcript was generated using AI and has not been reviewed for accuracy. Please be aware it may contain errors or omissions.

Speaker A

00:00:00.640 - 00:01:06.820

Hello and welcome to BJGP Interviews. I'm Nada Khan and I'm one of the Associate Editors at the Journal. Thanks for taking the time today to listen to this podcast.

In today's episode, we're talking to Dr. Steve Bradley. Steve is a GP and senior clinical Lecturer based within the School of Medicine and Population Health at the University of Sheffield.

Early diagnosis of cancer has been an area of research that is Steve's real strength. And we're here to discuss his recent paper here in the BJJP titled General Practice.

Chest X Ray Rate is Associated with Earlier Lung Cancer Diagnosis and Reduced All Cause Mortality A Retrospective Observational Study. Hi, Steve, Great to speak again and to talk through this paper.

I suppose I want to start by saying that, yes, we know that earlier diagnosis of cancer is a good thing because it can lead to earlier stages of diagnosis and treatment. And you start the paper with a short discussion about screening for lung cancer.

But talk us through why this, this alone won't solve delays in lung cancer diagnosis and what else we need to be doing.

Speaker B

00:01:07.540 - 00:02:14.620

So, yeah, this context is really important because screening is a hugely important development and the UK has led in many ways on lung cancer screening using low dose ct. And this, we hope is going to be very, very beneficial for patients.

But it would be a mistake to think that this is going to solve the problem of lung cancer. And there's a few reasons for that.

One is that only about half of people who get lung cancer would have been eligible for screening because screening concentrates on the highest risk population. And also we know that only about half of people who are invited for screening actually choose to participate in screening.

So the upshot for general practice really is that most patients are still going to be coming through by symptoms and in the same way.

So screening is good news in terms of lung cancer detection, but we still need to do as well as we can in terms of picking these patients up through symptomatic pathways. And actually, this is something we touched on in an editorial for BJGP about a year or 18 months ago, I think.

Speaker A

00:02:15.020 - 00:02:20.300

Yeah. So talk us through that. What was that editorial focusing on? Just for people who may not have had a chance to read it.

Speaker B

00:02:20.620 - 00:03:10.660

So it really was really discussing the situation where we are now in terms of awaiting for a national screening program for lung cancer screening and also considering the role of general practice.

So we set out that, just as I've said, that the role of gps is still going to be very important for lung cancer detection, but also that there are certain considerations that are important for GPs in terms of understanding what the program is, because a lot of patients might come to us to talk about lung cancer screening.

So it's good for us to have a basic understanding of what's involved and also some issues around the data that lung cancer screening uses, particularly smoking status.

So it becomes particularly important for our smoking records to be as accurate as possible because a lot of decisions around eligibility for lung cancer screening may. May hinge on that.

Speaker A

00:03:10.740 - 00:03:20.340

And just talk us through. So what were you trying to do in this paper?

So in this paper you were looking at people sent for chest X rays in different practices, but talk us through why you wanted to look at this.

Speaker B

00:03:20.980 - 00:04:06.250

Yeah, so this, this study was really inspired by earlier work which looked at rates of endoscopy requested from general practices and how that might affect outcomes for upper gastrointestinal cancers in terms of. Of when they are detected, what stage they are detected at.

So One of my PhD supervisors, Matt Callister, had had this idea for this project, I think, going back around 15 years or longer, as to whether we could look at practices in terms of how much they use chest X ray, and then look at what happens to patients who are diagnosed with lung cancer, in terms of what stage of lung cancer they are diagnosed with, when they are diagnosed, and also with their survival as well. So that's really what we aim to do in this paper.

Speaker A

00:04:06.490 - 00:04:17.050

Talk us through just briefly what you did and just. Yeah, it was quite a big study. But yeah, just briefly, how did you go about doing this?

Because you looked at quite a lot of data, didn't you, to try to look at these different associations?

Speaker B

00:04:17.849 - 00:05:13.860

So we took data on general practices from 2013 to 2017. So this is general practices in England. And we used the kinds of data that's available on general practice profiles.

That website is also known as fingertips. And we got information on how often different general practices were requesting chest X ray in a year from the Diagnostic Imaging Data set.

And then we also got data on lung cancer outcomes from the National Cancer Registry from the year after. So 2014 to 2018.

So we put those together and we had Data on around 160,000 patients diagnosed with lung cancer in that period and information on general practices. Around 7,000 general practices.

Speaker A

00:05:14.500 - 00:05:23.780

Let's go to what you found here. So what was that association between the rate of practice chest X rays and stage of cancer diagnosis? What did you find here?

Speaker B

00:05:24.520 - 00:07:23.330

So what we did was we broke up practices in terms of how often they were requesting chest X rays, and we did that in two ways. One was in five groups into quintiles and that was adjusted based on factors like demography of the practice, smoking status, et cetera.

And then we had another set of categories which was just based on what we call natural frequency. So just numbers that weren't into three categories that weren't adjusted.

And the purpose for that was we wanted to be able to have a way that people in practices or who are working in the health system could just eyeball figures and get a sense of where practices were and how this might affect outcomes. So we had those different categories.

And for the quintiles we found that practices in the top quintile of chest X ray requesting had both improved stage of diagnosis. So we find an odds ratio of 0.87 favoring early stage diagnosis. So that's stage one or two compared to late stage, stage three or four.

So an odds ratio of 0.87. So that's, that's a really quite substantial improvement. And also improvements in survival.

So hazards ratio of 0.92 favoring one year survival for that top quintile, 0.95 for five year survival as well. And that five year survival that's using only patients who survived to at least one year.

So that's, that improvement isn't just a reflection of the improved one year survival. So we feel this is really quite important.

The other categories with the three different groups that what we call the natural frequencies, we didn't see the quite the same scale effect in the top grip, the top third group, but that's, that's really probably a dilutional effect because they're broader categories. So the top group isn't showing us the same scale of effect.

Speaker A

00:07:23.650 - 00:07:39.410

And you've sort of alluded to this, but you know, each practice will have its own specific population and demographics. Was there anything at a practice level that influenced the rate of chest X ray requests or stage of cancer diagnosis or survival?

Speaker B

00:07:40.740 - 00:08:39.100

So in terms of how often practices request chest X rays. So we've looked at this previously in a paper published in bjgp.

It was called something like association of chest X ray rate and general practices and populations. And what was surprising just was really how minimal the effect of any differences at all are and recorded characteristics between general practices.

So I think in its entirety what we looked at, all of the factors, including differences in populations and practices, accounted for less than 20% of the variation. So most of the variation that's happening is not from things that we can record or understand.

Probably most of this variation is to do with human beings and cultures and what we believe about chest X ray and how valuable we think the test is and adjust our habits and things like that. And that's important because those things can be changed and we can influence those things.

Speaker A

00:08:39.900 - 00:09:03.270

Yeah. And I think that's sort of where I was going to go next, really. And I guess the question is why?

So why would practice level, sort of rates of chest ray, chest X ray ordering impact on lung cancer diagnosis and survival? And I know that the data here might not have answered that question, but what are your best guesses about this?

And you've alluded to this a bit in terms of human factors.

Speaker B

00:09:04.150 - 00:10:40.920

Well, I mean, I think the mechanism this would be working is that if people are doing more, they're taking the opportunity to organize more chest X rays for these very common symptoms. And if you look at the NICE criteria, which they say we should consider an urgent chest X ray, they're really very broad, common symptoms.

Things like cough, shortness of breath, weight loss, chest pain, also raised platelet count, tiredness.

So really symptoms that people mention all the time, People might mention this as an aside, or they might mention it during a chronic disease review or something else.

So there is probably flexibility in terms of what primary care teams do, in terms of what they do with those kinds of disclosures, whether they organize tests like chest X ray or not. So lung cancer is challenging because it usually presents with symptoms which are very common, very non specific.

For example, a cough is the most common symptom, but cough is a very common symptom in general.

So our thinking is really that if teams are more vigilant about how they investigate these common symptoms with chest X ray, they'll be picking up disease earlier.

It's important to say there are limitations with chest X ray, but I think this evidence really gives us some grounds to say we should should use the test, even understanding that there are limitations in terms of accuracy. And although it isn't always successful in picking up lung cancer, it does do it a fair amount of the time and we can use it effectively.

Speaker A

00:10:41.560 - 00:11:07.350

So we both used to work in Leeds where there used to be an open access chest X ray clinic or a self request chest X ray service. So this is where people aged 40 and over could, with symptoms potentially suggestive of lung cancer, could just walk in and request a chest X ray.

Do you think that services like that should be made more widely available if more chest X rays potentially could lead to earlier diagnosis?

Speaker B

00:11:07.750 - 00:12:58.690

Yeah. So this is a self request chest X ray service. So not to be confused with open access which tends to be used for the way that we request chest X rays.

You know, you request, the GP requests it on the computer and then the patient turns up within two weeks, say, and they're able to just get it at their convenience. So, yes, self request services have been used in Leeds now for well over a decade and also are being used in Manchester and elsewhere.

So, yes, I do think these could be used more widely and we know that they are successful in reaching the right patients, patients who have a history of smoking and patients from less affluent communities as well.

And we know also that the proportion of these, these chest X rays that are leading to cancer diagnosis is around equivalent of what gps request as well. I think these services are a good thing, really, because there are patients who find it hard to access general practice to get appointments.

There are patients who also don't want to talk about their symptoms and are worried that they're going to be given a lecture about smoking if they come with respiratory symptoms. And so it just suits some patients.

I think in principle it's a sensible thing to do, but I think, particularly at the current time, where access to general practice is so difficult, or even where it isn't, even where it isn't that much of a problem, patients still have a perception that it is going to be very difficult to get a general practice appointment. So I do think it's a valuable thing to do. And we published a paper in BJGP at the start of this year.

It was recommendations from the Roy Castle Lung Cancer Foundation Group on symptomatic diagnosis. And that was one of the points made in there about expanding these services.

Speaker A

00:12:59.090 - 00:13:19.030

And you've mentioned about some of the limitations of chest X rays, and I know that you've done a lot of work around chest CT as well. And what do you think the role is of a chest ct? And do you think that patients with symptoms suggestive of lung cancer.

Is there a balance between requesting a chest X ray or chest CT in general practice? What are your thoughts about that?

Speaker B

00:13:20.310 - 00:15:30.850

It's difficult.

The guidelines internationally almost all say that for most potential lung cancer symptoms, except for hemoptysis, coughing up blood, the chest X ray should be the first line test. But we know that there are problems in terms of accuracy.

It's missing around about a fifth of cases of lung cancer, which is not something we should be complacent about because this is such a devastating disease and we need to pick it up as soon as possible.

But there are really practical limitations around ct, and particularly in a country like the uk where we just have a lot less access to CT than other high income countries like Australia and the us. So I do think it's a balance actually.

I think it would be a mistake to just give into a council of despair and that we think chest X rays rubbish and isn't worthwhile, particularly when it's going to be difficult for us to get CTs for our patients. But at the same time CT's kind of drawbacks as well, even if we did have perfect access in terms of over diagnosis as well.

So in terms of what we should do practically, this is a kind of classic problem for gps, particularly in countries like the uk, where we have limited access to ct. And in theory all English gps now have access to urgent direct access ct.

I think it's probably more complicated on the ground and I'm not sure if that theory has translated into practical reality for a lot of GPs working in England. So I think GPs really just need to use their intuition quite often. I said just use. It's actually a really difficult thing to do.

But it depends, in short, it depends on how worried you are, you are about your patient and how concerned you are. And also it is the case that a lot of these symptoms overlap with other serious conditions, not just cancer.

So even if you do get the perfect test that rules out lung cancer, the job isn't over there. You, you probably do need to think about other serious conditions as well.

Speaker A

00:15:31.650 - 00:15:48.630

Fair enough.

And yeah, we could sidestep into whole discussion here about so called gut feelings and when clinicians feel inclined to make certain decisions based on that intuition, that clinical intuition as you describe, which I think is a better way of conceptualizing gut feelings. Really.

Speaker B

00:15:48.870 - 00:16:14.720

Yeah, I mean I think we could be, we could be frustrated by this and, and, and want clearer guidance and clearer evidence at the same time. This is really our job as clinicians and it's something we should take pride in and how we think through these problems.

And this is why, this is why we're, we're here. So it is, it is one of the difficult aspects of the job, but it's also an aspect of the job we should take pride in as well, I think.

Speaker A

00:16:14.800 - 00:16:26.080

And Steve, this is sort of, you know, your, really your area of focus and research and knowledge, but is there anything else you want to add here about chest X rays in general practice? Just before we wrap up?

Speaker B

00:16:26.240 - 00:17:23.730

I think the take home here really is the chest X ray is a useful tool. The radiation dose is negligible. It's equivalent to a few days of natural exposure to radiation and the test is useful.

So if the possibility of lung cancer is crossing your mind, I think a good first step is doing a chest X ray.

And it's worthwhile knowing what just having the odd glance at what the NICE NG12 symptoms for possible lung cancer are because it's really surprising how broad these are. And a lot of our patients will come to us with these, with these symptoms.

The other thing is that an increasing...