Cancer information Cancer treatment

Colon Cancer 7

How accepted are the stents right now? Well things really changed in 1993. This was the first randomized controlled trial comparing the plastic rigid-type stents to the … this was actually the Wallstent that was used, a randomized trial and following this the stents really gained a lot of acceptance and began to be used much more frequently. This study, as you will recall, isn’t a perfect study in that patients were kept in the hospital for a long time for the plastic stents, for dilation and general anesthesia and such, but the important take-home message is that the expandable metal stents were just as effective technically and functionally, but the complication was much less significant for the expandable metal stents. Perforations, pneumonias, migrations, didn’t occur in this limited study. And that’s really held true over the last six or seven years. Self-expanding stents require minimal pre-stent dilation. As I mentioned, the smaller caliber stents can be placed typically without any dilation whatsoever. The technical success across the board, looking at different series, between 90-100% - and most importantly - the functional success. The patient actually gets relief of dysphagia again at a very significant rate.

What are the complications? Well they are slowly going down as operators gain more experience, but most significantly perforations now are occurring at a less than 1% rate. Serious complications including major bleeding, sepsis, perforation, across the board are somewhere in that 2.5-3% range all together. One caveat to keep in mind, your patients who have already received radiation therapy, bleeding, perforations, other complications occur much more frequently in this sub-population of patients.

Cancer treatment

Colon Cancer 6

This is just showing the stent now in position. The guide-wire and delivery system is very carefully being removed, but you can see the annulated portion of the tumor in this region here with plenty of stent on each side. This device can actually be removed, or you can adjust this position after its placement. Keep in mind, be very careful when you remove the delivery system. It’s possible to snag on any of the stents and pull it out. This is just showing an endoscopic view of the lumen. This is an 18 mm diameter and the patient is now swallowing contrast material and you can see that pass through quite nicely off the distal end. So again, a successful placement.

A second video clip just showing the placement of Wilson-Cook Z stent. Again it comes in different sizes. It’s coded and it has flared ends on both sides. That’s hopefully to anchor the stent once it is positioned. The delivery system here is a bit different. More of the typical sheath retraction delivery system. But just watch. The tumor is located here and the upper margin is about there, but just watch as this stent is deployed there will be very minimal retraction. So fairly precise measurements can be made and hopefully you can maintain that precision when the stent is deployed. Here you can see the stent being slowly released as the sheath is being withdrawn, and you’ll see the delivery system and guide-wire have been carefully removed through the stent. This kind of device doesn’t quite have the radial force, as mentioned, of the EsophaCoil so you have to be very careful. It may not be fully opened for a minute or two. Always allow plenty of time for full deployment of the stent. In some situations you may actually want to go back down with the scope afterwards and carefully pass a TTS balloon to kind of aid in the full expansion of the stent. So here we are removing the guide-wire, you can look inside and if you think you need to, suggested by the radiographs, you may want to pass a TTS balloon and help the stent deploy a little bit further.

Okay, slides again. Those are two examples where things went pretty well. Does it always go that way? Of course not. This is called a “birds nest sign”. This is an EsophaCoil where the distal and proximal portions of the stent were beautifully released, and in the mid-portion unfortunately the whole thing just coiled up. Just kind of happened that way. Fortunately this can be taken care of. You can remove the EsophaCoil by grabbing the proximal end and just carefully removing the stent, and then a second was placed allowing for adequate lumen stenting.

Colon Cancer 5

Finally, the last self-expanding stent is the Wilson-Cook Z stent. This is a stainless steel product with interlocking mesh triangles, again with a polyurethane coating to prevent tumor ingrowth. It comes in different sizes. One of the nice features of this stent is when it is deployed there is very minimal retraction. That is, when the stent pops in it doesn’t shrink down very much, so you can very accurately gauge the placement of this stent and that is really handy when you are placing a proximal esophageal stent where you are worried about respiratory compromise, and a few other applications as well.

This table is in your syllabus but it kind of outlines some of the specs of the different stents. But keep in mind, the size of the delivery system is very important. If you have a large delivery system that is going to require a number of dilation maneuvers perhaps to place that, whereas if you have a very small delivery system, 18 French or 24 French, it’s quite easy to pop this in without even a single dilation maneuver. Four of the five stents are now covered, and that’s important for preventing tumor ingrowth and also for sealing tracheoesophageal fistulas. The radial force is quite different. If you’ve ever felt the EsophaCoil, it has kind of a firm, strong feel. Whereas the Ultraflex seems quite flimsy but they have different properties there. And again, degree of shortening is very important. I’ve mentioned the Z stent has very little shortening that occurs.

I’m going to show a little video tape again. The placement of a couple of stents. For those of you who haven’t been doing this much, just to show … first, the EsophaCoil. This is typical adenocarcinoma of the distal esophagus. It’s important to note where the tumor is so you have to mark the tumor margins both externally and internally. This is injecting radiocontrast, either lipid or water soluble. There’s already a mark distally. I think you can just see it, and now injection proximally into the margin of the tumor so you can gauge your stent placement. You have to size your stents. They come in different sizes, different diameters of course. We try to get at least 2-3 cm of stent beyond the proximal and distal margins in order to allow for the shrinkage which may occur. Once the stent is passed through the stricture area, the EsophaCoil has kind of a tricky delivery system. You have to release three different tabs. The first tab is the distal release, which releases the … kind of a string release device which allows the distal part to be released. And you turn the device and release the proximal portion of the stent. Again, you notice the shrinkage which occurs, a fairly significant amount. It kind of bunches up and then finally the middle part right across the stricture is released, which allows the full deployment of the stent and hopefully the coils are all fitting together nicely like they are supposed to. Again, keeping in mind that this is important when you gauge what size of stent you should put in. If you have a 6 cm tumor you probably want at least a 10 cm or 12 cm stent, especially when using a device like this.

Colon Cancer 4

What about rigid prostheses? Those of you who have passed a couple of the Celestin type or other rigid type tubes probably get a visceral response just looking at this slide. It’s a fairly uncomfortable procedure both for the endoscopist as well as the patient, but basically this is where a rigid plastic tube is shoved through the distal tumor with the use of a pusher-tube device. What’s the problem with this technique? Well, technically it’s difficult to perform. These tubes are big. The outside lumen is about 18, the outside of the diameter of the tube is typically 16-18 mm in size, so it requires fairly aggressive either single or serial dilatation maneuvers in order to allow the tube to be eventually advanced. Frequently general anesthesia is necessary for the patient to tolerate this procedure. Again, when you are pushing fairly vigorously with this device, or with the dilation maneuvers, perforation is a concern. Looking at all series, it averages about 10%. These are not small perforations. These are usually the big rips. The mortality per procedure, across the board for placing this type of tube, is about 2-4%. So it’s quite significant. Once these tubes are in position they don’t always stay there. The migration rate averages between 20-40%. They can pop proximally or distally as well. So again, migration and perforation, significant problems.

Laser photoablation is ideal for an exophytic, non-circumferential type of tumor. Again that fleshy type of tumor. And with a couple of laser sessions you can see that the tumor melts away, and with further efforts you can see the laser being fired. This is again with the YAG laser. You can create a pretty significant lumen. What are the downsides? Obviously it is expensive technology. It typically takes a couple of sessions at least to get the patient to this point where the lumen is a relatively decent patent size, and also downstream the tumors come back, the patients have to return. On average, patients who have laser photoablation therapy as their only endoscopic therapy average 4-5 endoscopic therapies during their remaining lifetime. So that’s one of the downsides as well.

The new kids on the block are the self expanding metal stents. They were first modified for esophageal use about 1991. This is an example of the Schneider Wallstent in place. The advantage of this type of device - obviously those of you who place it are quite aware of this - but it can be mounted onto a delivery catheter where it’s held in check with a sheath. When the sheath is withdrawn the stent is deployed, and then it provides a force against this esophageal tumor, hopefully providing a nice lumen such as seen here where the lumen is about 18 mm. There are now currently four commercially made stent devices. This is an example of the EsophaCoil, made by Medtronic. This is a nitinol device, nitinol alloy which is a combination of nickel and titanium. It is kind of a flat ribbon which has a nice memory feature, so the stent kind of recoils back to its original position after deployment. It has excellent radial force. It’s a nice stent to use in the distal esophagus, for example, when extrinsic compression is a concern. Once deployed, the coils are supposed to slide nicely and snug together hoping to prevent ingrowth of tumor. This is the Ultraflex device, both in the uncovered and covered. Again, a nitinol-type of compound metal. It has a very soft flexible feel to it so it’s a handy stent to use when there is a sharply angulated stricture. This is the Schneider Wallstent. The version on the right is the Wallstent I, which has a good radial force but the trouble was it was packaged into a 38 French catheter. Fairly stiff delivery system, which then allowed this stent to be deployed. Schneider has subsequently made the Wallstent II version which still provides a good lumen size, 18-19 mm lumen size, but this device is now packaged onto a 6 mm diameter catheter. So a very thin flexible catheter that can be placed much more easily and without the usual pre-dilation maneuvers compared to the old Wallstent version.

Colon Cancer 3

What’s the best technique? Well, obviously one that can be accomplished quickly, conveniently for the patients where they are not tied to an endoscopy center repeatedly, the lowest cost, and the lowest morbidity and mortality. Palliative management, a number of guidelines; we’ve got to confirm the diagnosis. The location, length, other characteristics of the tumor are important to define. Is this primarily an exophytic tumor or rather is this extrinsic compression from a tumor outside the esophagus perhaps? Is there a fistula present, and has adjuvant therapy being contemplated?

This is an example of an esophageal tumor, primarily exophytic as you can gauge by the roughened tissue within the midportion of the esophagus. This was a squamous cell malignancy. Now how should we manage this tumor? If you look at the relatively ancient literature, back in 1845 there was a Frenchman who used a decalcified elephant tusk - basically a hunk of ivory - the center was bored out and he placed that into the esophageal tumor unsuccessfully, unfortunately. Ten years later an Englishman named Sir Charles Simmond used a piece of carved boxwood, a six-inch piece of wood. Jammed it into an esophageal tumor and the patient did well for about three months.

So those are the first reported cases of so-called endoscopic intervention, but our therapy has actually evolved since then. In the modern era it is important to at least consider now radiation therapy. There are special protocols designed to shrink tumors rapidly over a short period of time, such as over ten fractions, but importantly, the response rate is quite variable especially for the responses for adenocarcinomas. The time to see tumors shrink is also quite variable. It can take as long as six weeks, even in the responders, before you’ll get a significant effect - although the duration is usually around the time of five or six months where the benefit will be maintained. Importantly, stricture formation in patients who have radiation therapy can be a significant complication where endoscopic therapy is again called upon.

Since the advent of the fiberoptic endoscope, a number of interventional technologies have evolved, and listed here in the order in which they appeared. Dilation therapy, simply using a bougie or a balloon dilator is simple, quite easy to perform, but as you would imagine, the benefit is quite short-lived and typically, repeated dilatations are necessary. Aggressive dilatation can result in a dilatation in up to a quarter of the patients. Injection therapy is also quite simple, technically. You basically inject absolute alcohol or some other solutions into a kind of fleshy, soft, exophytic tumor where it works the best, and you may see some fluffage which occurs with that. But again, as you can imagine, with extensive fibrotic circumferential tumors this therapy doesn’t work very well.

Colon Cancer 2

What about the second indication, for effective palliation? Again, very limited numbers here so take this certainly with a grain of salt, but effective palliation can be achieved with an expandable stent. The duration of therapy when stents were positioned averaged about 17 weeks. One patient went as long as 64 weeks. What are the problems? Certainly migration in the colon with colonic motility and especially when the stent is placed at an anatomical curve, the splenic flexure for example, those stents are much more likely to migrate. So the numbers are still quite high. From Dr. Baron’s study of 25 patients, again the concern is migration in about 20%. Perforation occurred in four patients and that was primarily, they thought, due to the balloon dilation performed before the stent was placed. One interesting point, when they placed the stent, provided contrast material to check its site and to rule out perforation, and found an unrecognizable site of proximal obstruction in a couple of patients. So obviously that’s a limitation of this process.

This is very flexible. The endoprothesis device, it’s very flexible and the nice thing about that is it can be mounted on a very very small delivery system. Again, this has now been recently approved by the FDA. This is the delivery system with the typical stent mounted approach where the sheath is then withdrawn and the stent is then released. You can see the radiopaque markers which aid in fluoroscopic placement and guidance. Again, the retraction is a problem. There is a fairly significant amount of retraction which occurs with these devices so you kind of have to measure that as best you can. The main advantage is, as shown, it can be passed through the biopsy channel of the colonoscope and here we will see the stent being placed across the stricture here, the stent is being deployed. You can see the kind of shrinking down again. This is where the stricture is and now you can see contrast material, I hope you can see that, passing through the stent itself.

There are 10,000 cases per year in this country of esophageal cancer, and unfortunately most of those are un-resectable at time of presentation. The five-year survival was quite poor, and the life expectancy averages about six months in patients with un-resectable disease. Now as endoscopists, and physicians, our goal is to relive the most bothersome symptom for the patient, that is, the one that affects their quality of life most significantly, and that is dysphagia, and at the time providing nutritional access and also a means to prevent aspiration.