Hi, everybody. This is Rishi Agrawal.
This video is going to be an overview of lung cancer staging.
Staging uses the TNM system meaning tumor, node, and metastasis.
I'm going to go over each of those categories in other videos.
This is the roadmap for today.
We're going to talk first
about the description and uses of staging and then move to terminology and syntax.
And then finally, talk a bit
about site specific considerations in lung cancer staging.
So what is staging?
Staging is simply categorization of the extent of a disease.
Cancer is probably the best example, but there are other very common
staging systems,
for example, there are staging systems for heart failure and renal failure.
Sarcoid has a staging system ranging from 0-4,
and there's even cognitive diseases like dementia that are staged.
What's the purpose of staging?
One of the obvious purposes of staging is that it's a shorthand
way of communicating the disease extent to other practitioners.
For example, instead of saying that the patient has a 2 cm tumor
with metastatic disease to the contralateral mediastinum,
brain, and liver, you can just say that it was stage IVB.
Second, it's used to guide treatment, knowing the stage
is kind of like the first branch point for the initiation of treatment.
For example, whether surgery is indicated or not.
It doesn't tell you everything that you need to know about treatment, though.
Other details are important, of course, like the patient's performance status
and cancer genetics, but the stage is a good starting point.
Third is that it's used to estimate prognosis.
Here's a graph of two and four year survival based on the stage
of lung cancer.
You can see that these survival curves are very well separated,
meaning that the increase in stage carries with it meaningful,
real world repercussions in terms of survival.
Finally, it aids in research.
When studying a certain therapy, the patient population has to be defined.
Without a universally accepted staging system,
research would be extremely difficult to coordinate among institutions,
and it would be difficult to apply the results to your patient population.
When we talk
about staging, there's two common types of staging that you'll encounter,
and those are clinical staging and pathological staging.
Clinical staging is based on the collection of all the patient data
up to the initiation of definitive treatment.
It includes the physical exam, the lab results,
imaging and biopsy results.
Now, if the patient's treatment plan also includes
resection of the primary tumor
and regional lymph nodes, then that information is added
to the clinical stage to give us the pathological stage.
In some patients whose treatment plan doesn't involve tumor resection,
they won't get pathological staging, just clinical staging.
The clinical stage and the pathologic stage can differ,
especially if biopsies hadn't been obtained as part of the clinical stage.
For example, an enlarged lymph node on CT is positive for metastatic disease
only about 60% of the time, and lymph nodes that are hot on PET
are pathologically positive only about 75 to 85% of the time.
The way these are denoted in practice and in the literature
is by using the prefix 'c' for clinical stage or
'p' for pathologic stage right before the stage classification
or sometimes right before the T, N, or M category.
You might hear about other kinds of staging.
There's post therapy staging which is done after initial treatment
to measure response, most commonly in the case of neoadjuvant therapy.
There's autopsy staging which occurs after death.
And then there's retreatment staging, which happens when the patient
has a disease free interval and then they have a recurrence.
These are
two lists of words that were published by the American College of Surgeons.
This first list is used to mean tumor involvement,
and the second list is used to mean no tumor involvement.
I'm not saying that these lists are universally accepted, but
the main idea is that when we use a word that might mean something in our heads,
but it may mean something different in the heads of the recipient
of that report, so it's important to use the words that we choose wisely.
OK, for lung cancer staging specifically, we're currently on the 8th
edition of the TNM staging system, which was released in 2017.
TNM 7 was published in 2009.
I'm recording this in 2022.
So if you're watching this in 2024 or 2025,
you may want to check to see if there is a 9th edition of TNM.
TNM staging is used for non-small cell lung
cancer and bronchopulmonary carcinoid.
It can also be used for small cell.
However, in practice, small cell has a different
staging system that is separate from TNM.
The data for this staging system comes from 77,000 patients with cancer
diagnosed between 1999 and 2010.
TNM staging works by collecting data on tumor size
and extent of local invasion, regional lymph node spread,
and distant metastases including distant lymph nodes.
T, N, and M are referred to as categories not stages.
The stage is determined by combining the T, N, and M categories together
and using a table like this one to come up with a stage.
I'm going to be talking about each of
these categories in a separate video, so stay tuned for that.
All right. That's it for this video.
If you have any questions, please let me know in the comments below.
Thanks.