0:01

The most important things for a radiologist is how

0:03

to use lung rads in interpreting lung cancer screening cts.

0:08

We'll talk about why Lung RADS was developed Core principles

0:11

of Lung rads the most recent updates in the

0:15

December, 2022 version.

0:17

And importantly, this new concept of step management

0:20

lung rats is used not only in the US

0:23

but it's used around the world in many screening programs.

0:26

We're now at our third version.

0:28

It's been in use for 10 years.

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We have a committee of 12 individuals

0:32

that are multidisciplinary

0:33

and help to make these updates impactful

0:36

and it impacts patients

0:37

who are enrolled in lung cancer screening programs.

0:40

It's been cited in well over 200 publications as well

0:44

and uses a standard

0:46

for lung cancer screening interpretation.

0:49

The first version came out in 2014 shortly

0:52

after the preventative services task force

0:54

recommendation Medicare coverage.

0:57

We had an update in 2019

1:00

and the most recent update was in December, 2022.

1:04

Lung rats provides a common lexicon in definitions

1:06

for interpreting screening cts to standardize practice

1:10

among radiologists for communicating

1:12

with ordering providers.

1:13

It defines a positive screen addresses uncertainty

1:17

and positive screen management facilitates quality

1:21

insurance improvement.

1:22

Particularly you can use it to look at your radiologists

1:25

and how they interpret lung cancer screening cts similarly

1:29

to how your practice probably does that already

1:30

for screening mammograms with your radiologists

1:34

and long ads will evolve as new evidence comes to bear.

1:39

The central tenets of lung rads are to look at nodules

1:42

by their size and their consistency.

1:45

We look at their size at baseline

1:47

and look for growth versus stability with time

1:50

nodule Consistency is on the solid to ground glass

1:54

or nonsolid continuum.

1:56

We have added cystic nodules in the most recent

1:59

update for lung rats.

2:01

And then you can have benign appearing calcifications

2:04

or fat that would indicate the nodule is benign

2:07

and not lung cancer related.

2:09

Importantly, we have the concept in lung rats of benign

2:13

and benign behavior versus clinically active cancer.

2:17

And this really makes you ask, well, what is cancer?

2:20

Is any nodule that has cancer cells under

2:22

the microscope cancer?

2:24

Well, technically yes, from a histopathologic standpoint,

2:27

but if it's not behaving like cancer in the human,

2:32

if it is sitting there

2:33

and not growing as a small nodule, the benefit

2:37

to treatment such as surgical resection is outweighed

2:41

by the harm in resecting something

2:43

that would be over-diagnosis

2:45

and not likely to do anything in

2:47

that individual over their lifetime.

2:50

It's a difference between living with cancer

2:53

and dying of cancer.

2:55

Cancer detected that will impact you

2:57

during life cancer detected that will not.

3:00

And the likelihood of

3:01

that is based on some of these criteria.

3:02

We've talked about size, growth, and consistency.

3:07

We know that using Lung RADS reduces the number

3:10

of false positives

3:11

that were seen in the national lung cancer screening trial

3:14

from about one in four to one in 10.

3:16

And so we know that it is impactful

3:19

as an application in patients who are undergoing screening.

3:23

Let's first look at nodules by their consistency.

3:26

We have solid nodules, pure ground glass nodules

3:30

through which you can see branching vessels

3:31

and nodules that have a bit of both components,

3:34

solid and ground glass.

3:36

So I ask, which

3:38

of these three nodules is most likely to be cancer?

3:42

Well, solid nodules are the most common.

3:44

So it's kind of a trick question.

3:46

We see more solid nodules than any other nodule type part.

3:49

Solid nodules are most likely to be an invasive cancer

3:52

that will impact the person who has this finding.

3:56

And ground glass nodules are likely carcinomas,

4:00

adenocarcinomas in situ, and this gets the nodules

4:03

or cancers that somebody can live with versus dying of.

4:07

So not an easy question to answer.

4:10

We get some of our size thresholds for what nodules go into

4:13

what categories based on information like this from the

4:16

International LCAP program and doctors, uh, Claudia Husky

4:20

and David Yitz, who are pioneers in lung cancer screening,

4:24

performing the first lung cancer trial in the US

4:27

and one prospective cohort many years

4:29

before the National Lung Screening trial, uh, was performed

4:33

and it was their evidence

4:34

and their data that helps support the performance

4:37

of doing a randomized trial.

4:39

In looking at over 21,000 individuals

4:43

who had baseline cts in their practice over a five-year time

4:46

period, they looked at nodule size

4:49

and they looked at the positive screen rate as well as

4:53

what happens downstream in terms of workup.

4:56

And so looking at nodules that were five millimeter

4:58

or larger, 16% um, of patients had an abnormal screen

5:03

or a positive screen.

5:05

If they went up just one millimeter to six millimeters, 10%

5:09

of people had a positive screen

5:12

and 36 per percent less downstream tests are performed

5:16

because of having a lower positive screen rate.

5:18

And for each millimeter you go up, your positive screen rate

5:22

of course goes down,

5:24

but at some point your positive screen rate will be so low

5:26

that you're missing actionable cancers.

5:29

So where's the right trade-off?

5:32

They also looked at the nine month delay in cancer diagnosis

5:35

across each of these categories

5:37

by going from five millimeters to six millimeters

5:41

to define a positive screen

5:42

and decreasing the positive screen rate.

5:45

No patient had a nine month

5:46

or longer delay in their lung cancer diagnosis,

5:49

but when going from six millimeters

5:51

to seven millimeters leaving a 7% positive screen

5:55

rate, 5%

5:57

Of people had a nine month

5:58

or longer delay in their cancer diagnosis.

6:01

And this continues to grow up

6:03

as you increase these nodule size thresholds.

6:06

So in lung rads for solid nodules,

6:08

which is the preponderance of nodules,

6:10

you'll see six millimeters as an important cutoff between

6:14

positive and negative screens.

6:16

Categories two versus category three.

6:18

So this is some of the evidence

6:20

that was used in developing lung rads.