Treating Early Stage Rectal Cancer With Endocavitary Radiation


July 28, 2009 — Treatment for rectal cancer usually involves surgery, which can have serious long-term side effects, particularly if a colostomy is required. For select patients with early stage disease, endocavitary radiation therapy – or endocavity radiation therapy – offers an alternative to surgery with similar local control rates. Siteman Cancer Center radiation oncologist Parag Parikh, MD, explains how it is performed and why it is offered at only a handful of centers nationwide.

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On this edition of Cancer Connection, we’ll talk about endocavitary radiation, what the procedure is and who’s a good candidate.

Host: Thanks for downloading this podcast from the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis. I’m Jason Merrill. Of the 150,000 cases of colorectal cancer diagnosed annually, more than 40,000 are rectal cancer. At a few centers in the country, an alternative to open surgery exists for early stage patients called endocavitary radiation therapy. To tell us more is Parag Parikh. He is a radiation oncologist at the Siteman Cancer Center. Dr. Parikh, thank you for joining us.

Parikh: Thanks. Thank you for having me.

Host: Let’s start at the beginning. What is endocavitary radiation?

Parikh: Endocavitary radiation is the use of focal radiation therapy delivered directly to a tumor, such as the tumor in the rectum. The way we perform this procedure is we work hand in hand with our colorectal surgeons. We place the patient in a position like they would have a digital rectal exam or a colonoscopy, and we use a special proctoscope to aim the radiation therapy device directly at the area of a rectal tumor.

Host: Now you said you work in conjunction with surgeons. Is this an alternative for some patients who would have gone on to surgery in the past?

Parikh: Absolutely. The use of this therapy is best for patients with early stage rectal cancer big enough that it would require a large operation. But in select patients, as long as we can debulk the tumor and they are otherwise eligible, we can use this as well as some external-beam radiation in lieu of a surgery where the rectum would be removed.

Host: What are the benefits? Are there fewer side effects in having this procedure rather than surgery?

Parikh: Definitely. In patients who receive external beam followed by endocavitary radiation for early stage rectal cancer, we are able to control the cancer to the same degree as we can with more radical surgery without the long-term side effects of changes in bowel habits, the risks of anesthesia or the hospital stay of a big procedure. Patients who receive endocavitary radiation end up coming in for two outpatient visits where they go home the same day.

Host: So two outpatient visits: How many hours and how much time commitment is it for a patient?

Parikh: Well, the whole total course of therapy normally involves one week of external-beam radiation, which are daily visits Monday through Friday for about 15 minutes to half an hour a day. This is followed by a month or month and a half break, at which time the patient returns as an outpatient for an endocavitary radiation procedure. That morning the patient would go to the outpatient surgery center, where they’ll be lightly sedated for us to perform the endocavitary radiation, which normally takes approximately half an hour. Then they are awoken and returned home to return in one week for the same procedure. After that, they’re done with therapy and followed by their local physician or the colorectal surgeon.

Host: You mention early stage patients. Is that really who this is focused on? Is that the best candidate?

Parikh: Absolutely. These patients who receive endocavitary radiation normally have what we call T1 or T2 tumors. These are real rectal cancers that do have the propensity to spread but may not need large operative procedures for their removal.

Host: Well for those patients, what would the standard protocol have been for them in the past?

Parikh: In the past it’s been very hit or miss. Before, knowing that these patients had tumors that could recur, almost all of them received large rectal operations where a large portion of the rectum was removed. This was very effective in eradicating the cancer but had many side effects, as you can imagine. There was then an urge to treat all these patients with just local surgery, maybe trying to remove a polyp endoscopically or just removing a small amount of the tumor. More research recently, especially by groups at Minnesota and Memorial Sloan-Kettering, has shown that the recurrence rates after these procedures were higher than expected, which means that a local excision alone may not be adequate treatment for these patients. We think that the use of a debulking procedure, external beam and endocavitary radiation may be the best combination for these patients: Enough treatment to get rid of the cancer but not too much treatment to cause the side effects of a big surgery.

Host: You mentioned it in the beginning, but how is the procedure specifically performed?

Parikh: The endocavitary radiation procedure is performed as an outpatient procedure with the colorectal surgeon and the radiation oncologist. The patient comes in in the morning to the outpatient surgery center. They are lightly sedated and placed in a position where they can receive a colonoscopy or proctoscopy. A specially outfitted procotscope that is compatible with our radiation source is placed right over the tumor or tumor scar by the colorectal surgeon and then held in place during the course of the radiation delivery while the patient is asleep. The patient is then woken up and returns home the same day.

Host: How involved was the Siteman Cancer Center in developing the procedure?

Parikh: Drs. Ira Kodner and Robert Myerson worked very diligently in developing this procedure almost 20 years ago. They’re one of the few U.S. institutions that offered this procedure and have published on it extensively over the years. We have shown in the patients that we select for this procedure that the local control rates are well within what you would find from doing a much bigger operation, and we continue to offer it to selected patients who we see.

Host: How would people know if they are eligible for the procedure?

Parikh: What I would recommend is that patients obtain their colonoscopy reports and any reports from other physicians that they’ve seen and come and visit both colorectal surgery and radiation oncology at the Siteman Cancer Center. At that point, we would repeat a proctoscopy, review the extent and stage of the cancer, perhaps even do an ultrasound at that time, and can give patients good advice on whether they would be a candidate for this procedure.

Host: So you said that Dr. Kodner and Dr. Myerson had begun doing this 20 years ago, but still there aren’t a lot of places doing this currently, correct?

Parikh: Unfortunately, no. The procedure takes a new type of cooperation between colorectal surgery and radiation oncology, and it was hard to duplicate this collaboration at other centers. Many other centers had purchased this endocavitary unit only to find that it did not perform as well as they might have expected. But because at our center we in radiation oncology work so closely with colorectal surgery, we’ve been able to successfully implement this. It takes the combination of the surgeon’s knowledge of the anatomy of the lesion as well as the radiation oncologist’s knowledge of the physical characteristics of the machine. The machine administers radiation only to a very superficial depth of tissue, so improper placement even by a few millimeters means that you’re not targeting the lesion.

Host: Dr. Parikh, thanks for joining us.

Parikh: Thanks for having me.

Host: For more information about rectal cancer, visit the Siteman Cancer Center online at or call 800-600-3606. Thanks for downloading. Until next time, I’m Jason Merrill.