0:00

This one I think should have been relatively straightforward.

0:04

This was a case of, um,

0:08

a large right-sided, tongue-based carcinoma that, uh,

0:12

is H P V positive.

0:14

So let's go over the normal anatomy of the subsite of the oral pharynx.

0:19

So we talked earlier about the oral cavity.

0:22

Now what we did is that we moved our yellow box more posteriorly.

0:26

So the anterior portion of the oral pharynx is the circum valley

0:31

papilla and the anterior tonsor pillar,

0:34

the posterior margin is gonna be the posterior pharyngeal wall.

0:37

The superior margin is gonna be at the level of the soft palate.

0:41

The inferior margin is gonna be the level of the molecular,

0:44

and then the lateral margin are gonna be at the level of the tonsil.

0:47

So the anterior tonsil pillar, the posterior tonsil pillar, and the tonsor foa.

0:52

So this is a schematic illustration of a tongue-based cancer.

0:56

Here's a schematic illustration of a soft palate cancer.

0:59

This is a schematic illustration of a tonsil cancer.

1:02

And here's the illustration of the posterior pharyngeal wall.

1:05

And these are all tumors here that are involved in the tongue base,

1:09

the soft palate, the tonsil, and the posterior pharyngeal wall.

1:14

So when we actually look at the staging system

1:19

or oral pharynx cancers, um,

1:23

what's in the United States,

1:25

the majority of oral pharynx cancers are going to be H P V positive.

1:30

So when we look at the staging,

1:31

the first thing that we should always do is measure the size of the lesion. So,

1:36

T one, if the tumor's less than two centimeters, it's T one.

1:39

If the tumor's two to four centimeters, it's T two. And if it's greater than,

1:44

uh, four centimeters, it's a T three.

1:48

The T four lesions are tumors that invade the larynx,

1:52

involve the extrinsic muscles of the tongue,

1:55

involve the medial oid muscle, the hard palate, or the mandible.

2:00

So in general, what you can do is you can describe some of the muscles,

2:04

I think Ashish.

2:05

What what I would try to do is that when I look at these,

2:10

if this tumor is involving this very, very lower area here,

2:16

this is the region of the root of the tongue.

2:18

So if I see a tumor that's involving the root of the tongue and the root of the

2:22

tongue as defined about the level of the circum valley papilla,

2:26

then I will specifically mention that in general,

2:29

because the tumors that we see in the United States are H P V positive,

2:34

their majority are gonna get treated with radiation and chemotherapy.

2:38

So I have to admit,

2:39

I don't talk too much about the involvement of the individual muscles,

2:44

but what I do specifically say is whether these tumors cross the midline.

2:50

Now, I just re uh, returned from India.

2:53

In the us as I mentioned before, the majority of oropharynx cancers

2:58

Are actually H P V positive. But in India, um,

3:03

they still have a lot of oral Ferris cancers that are H P V

3:08

negative. Now,

3:10

the reason why that's important is because the staging system is different.

3:15

So I gave a joint session with some radiologists and some E N T surgeons,

3:20

and the E N T folks told me the reason why there's a high

3:25

prevalence of H P V negative tumors in India is the

3:30

fact that there's still a lot of smoking and drinking in that population.

3:34

Whereas the United States, it has decreased. So as a result,

3:39

T one to T three is still between zero and four centimeters as

3:44

you see here.

3:46

But this is where it becomes more important to

3:51

identify the specific muscles of involvement.

3:56

So a T four A is invasion of the larynx and deep extrinsic muscles of the

4:01

tongue, medial OID heart palate. This is what we talked before.

4:05

But in T four B,

4:06

then you have to talk about invasion of the lateral OID muscles, the OID plates,

4:11

and nasal pharynx, the skull base or encasement the carotid artery.

4:15

So in H P V positive patients, we just have T four lesions,

4:19

but in H P V negative cases, there's T four A and T four B.

4:24

And because essentially T four A means that they could be surgically resectable,

4:29

then we do need to comment on the specific involvement of the, uh,

4:33

adjacent muscles that the tumor is either involving or not involving.

4:38

So in general, when we talk about depth of invasion for oral cavity,

4:43

that's particularly due to squamous cell carcinoma.

4:46

So the depth of invasion is, is a histologic diagnosis.

4:50

It's not a radiological diagnosis,

4:53

and people tend to confuse tumor thickness with depth of invasion.

4:57

Depth of invasion is actually a line drawn from the base basement membrane.

5:02

So here's a basement membrane,

5:03

you extrapolate it over and what the pathologist does is they look for tumor

5:08

that's below this line that

5:12

approximates the level of the basement membrane.

5:15

So they make that measurement from here to here.

5:18

And if that measurement is actually greater than five,

5:22

I believe it's five millimeters, um,

5:24

then that would be upstage at two a T two.

5:28

If it's greater than 10 millimeters, it upstages it to a T three. But again,

5:33

it's important to know that what we see radiologically is not necessarily depth

5:37

of invasion, that's just tumor thickness.

5:39

So specifically depth of invasion is a histologic diagnosis and not a

5:44

radiological diagnosis,

5:45

and it's predominantly used for squamous cell carcinomas.