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 prac