0:01

The next few cases will cover the approach

0:04

to evaluating treatment response in

0:06

patients who have undergone local-regional

0:08

therapy for hepatocellular carcinomas.

0:12

I'm going to start by just sort of

0:15

outlining a few general principles that

0:17

go behind some of the treatment options

0:19

that are available for patients with HCC.

0:22

While treatment options are multifactorial and

0:25

often require a multidisciplinary approach.

0:28

There are some general considerations

0:30

that outline many of these decisions.

0:32

And the first is that every patient is sort

0:34

of evaluated to see whether they can undergo

0:39

surgical resection of the lesion itself.

0:43

This is an option that really allows

0:45

for curative therapy, ideally.

0:48

They would like to resect these tumors if

0:50

possible, but as it turns out, most patients

0:53

are not really eligible for surgical resection,

0:56

either due to the amount of tumor involvement

1:01

or extension at the time that they are presented

1:03

to the referring providers, or, and or, because

1:07

of the degree of underlying liver dysfunction.

1:12

So either they have a lot of disease and

1:14

the liver is not doing very well, so they

1:16

can't undergo surgery in a very safe manner.

1:19

So the next option that I look for

1:21

is potentially liver transplant.

1:25

And this also allows for a curative option

1:28

in patients with hepatocellular carcinoma.

1:31

Now there's some eligibility

1:32

criteria for patients who are

1:34

allowed to get a liver transplant.

1:37

Some of these criteria include the size of

1:39

the hepatocellular carcinoma, the number of

1:42

hepatocellular carcinomas in the patient.

1:44

I'm not going to go through those

1:45

criteria, but one of the issues that

1:48

happens with transplants is there are

1:49

issues with lifelong immunosuppression.

1:52

You know, that has its own risks, but also that

1:54

there is a overall shortage of transplants.

1:58

So there's not enough transplants to

2:01

go around to supply all the patients

2:04

who need their livers transplanted.

2:07

So then for patients who are ineligible

2:09

for surgery or transplant, there

2:11

are a number of local-regional

2:13

therapies that one could consider.

2:16

And some of these can be used in patients

2:17

who are waiting to get a liver transplant

2:20

as a means to maintain their eligibility.

2:23

So when we talk about local-regional treatment

2:26

or therapies for hepatocellular carcinoma,

2:29

they can really be categorized as percutaneous

2:33

ablative therapies or transarterial therapies.

2:40

Now under percutaneous ablation therapies you

2:42

have a variety of options that you can do and

2:45

some of the more common ones that are used in

2:48

this day and age are radiofrequency ablation

2:51

or microwave ablation and these utilize thermal

2:56

ablation in order to induce tumor necrosis.

2:59

So you percutaneously enter a catheter or an

3:01

electrode essentially to the liver tumor, and

3:05

you current, in the case of a radiofrequency

3:07

ablation, or microwaves, in the same thing of

3:10

microwave ablation, and use thermal ablation

3:13

techniques in order to kill the tumor itself.

3:16

Now, there's certain criteria that

3:18

patients have to meet in order to be

3:19

eligible for radiofrequency ablation.

3:21

Ideally, these liver tumors are small, less

3:26

than three to four centimeters in size,

3:28

Ideally, when you look at them within the

3:30

liver parenchyma, these tumors are located

3:32

within a centimeter of the liver parenchyma

3:35

itself, and they're not close to any major

3:37

vessels or not very close to the biliary tract.

3:40

So when we look at it in the setting

3:42

of a tumor board, these are evaluated

3:43

by interventional radiologists and they

3:45

assess whether the patients are, uh,

3:47

candidates for this type of therapy.

3:50

The transarterial techniques both take

3:52

advantage of the fact that HCCs are a very

3:55

important derive their blood supply, therefore

3:58

their nutrients, from the hepatic artery.

4:02

So they're fed by the hepatic artery, and

4:04

if we are able to deliver chemotherapeutic

4:07

agents, or radioactive agents, through

4:09

the hepatic artery, you can induce direct

4:13

treatment of the tumor itself, and you

4:15

can also have an embolic effect, i.e.,

4:17

cutting off that blood supply to the tumor.

4:20

The two main treatments that are used for

4:22

transarterial therapies are transarterial

4:24

chemoembolization and radioembolization.

4:30

And this is done using a

4:31

radioactive element, uh, Y90.

4:34

And these generally are for more widespread

4:37

disease that needs to be treated.

4:39

It's not very, sort of, localized hepatocellular

4:41

carcinoma widespread disease within the liver.

4:44

However, radioembolization tends

4:46

to work better if there's evidence

4:48

of tumor thrombus in the vessels.

4:51

As opposed to, uh, not thrombus, in

4:53

which case sometimes would be better.

4:55

And in both these instances, you're

4:56

accessing the hepatic artery.

4:58

With TACE, you're giving

4:59

a chemotherapeutic agent.

5:00

With radioembolization, a radioactive agent

5:02

that is directly treating the tumor itself

5:04

and has a secondary effect of reducing its

5:07

blood supply, thereby, um, inducing necrosis.

5:11

So, in addition to developing a LI-RADS

5:13

to assess for liver lesions, the LI-RADS

5:15

committee, um, also developed a standardized

5:18

approach to evaluate patients after

5:20

they've received local regional therapy.

5:22

You know, the basic thing that you're

5:24

looking for after any sort of these

5:25

treatment regimens is an avascular cavity.

5:28

So if you have a hepatocellular carcinoma

5:31

that has arterial hyperenhancement within

5:34

it, and you have treated this tumor via one

5:37

of your techniques that you have over here,

5:40

you're looking for an avascular cavity.

5:42

Inside of it should be as dark or as black

5:45

as possible with a very, very thin rim, if

5:47

any, rim of tiny enhancement over there.

5:50

And so in terms of the treatment response,

5:53

LI-RADS sort of categorizes lesions as follows:

5:57

So you can have LI-RADS treatment

6:00

response equal non-viable.

6:03

That tells you that the tumor has

6:05

been treated in its entirety, there's

6:07

no internal lesional enhancement.

6:09

And if there's any enhancement, it's the

6:11

expected enhancement you see associated with,

6:13

uh, sort of the treatment effect of the tumor.

6:16

On the other hand, you can have LI-RADS

6:18

treatment response viable, so that

6:20

tells you that there is persistent

6:23

enhancement within this lesion.

6:25

It could be a regular nodular mass

6:27

like enhancement, and that enhancement

6:30

within it can have arterial phase hyperenhancement,

6:31

it can have washout, or

6:34

it has enhancement that's similar to

6:36

what it looked like prior to treatment.

6:39

In the middle, you have a LI-RADS

6:41

category that is equivocal.

6:44

So in these instances, you're just

6:46

not sure whether it's been adequately

6:48

treated or if there's a residual tumor.

6:50

And those patients are evaluated on short

6:53

term imaging follow-up to see if anything

6:55

has come of that finding that you saw.

6:57

And the subset of patients

6:59

will be LI-RADS non-evaluable.

7:01

These are ones who have imaging

7:03

studies that are either missing

7:05

certain sequences or are too motioning.

7:08

You just can't evaluate the presence

7:09

or absence of a residual tumor.

7:12

In terms of lesions that are qualified

7:15

as a viable tumor, LI-RADS has a specific

7:18

way that it wants to standardize how you

7:20

measure residual or recurrent disease.

7:23

For example, if you have an

7:24

HCC over here, it gets treated.

7:27

As a result, you have a cavity over here,

7:30

and, you know, much of it remains avascular,

7:32

but you still have, you know, an area over

7:35

here that is persistently vascular.

7:40

The best way, or the correct way,

7:41

to measure this is as follows:

7:43

You take the longest dimension through

7:45

the enhancing area of the treated lesion

7:47

without crossing the lesion itself.

7:49

So that instance would be somewhere

7:51

from here all the way to about here.

7:54

You take this measurement, provide

7:56

that measurement, and say that's the area

7:59

of residual viability associated with

8:02

this treated hepatocellular carcinoma.