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Colon Cancer Treatment: Making the Right Choices

Posted Aug 24 2008 1:49pm
DAVID R. MARKS, MD: Hi, and welcome to our webcast. I'm Dr. David Marks. Chemotherapy is commonly used to treat cancer, but only a few chemo drugs are effective in treating colon cancer. This may be changing, though, because a number of new agents have shown promising results.

Here today to talk about these new drugs, are two experts. First is Dr. John Macdonald. He's an oncologist at St. Vincent's Comprehensive Cancer Center in New York City. Welcome.

JOHN MacDONALD, MD: Glad to be here, David.

DAVID R. MARKS, MD: Next to him is Dr. Michael Lieberman. He's a colorectal surgeon at the Weill Cornell Medical College. Thanks for being here.

MICHAEL LIEBERMAN, MD: Thank you, David.

DAVID R. MARKS, MD: When is chemotherapy used in colon cancer?

JOHN MacDONALD, MD: There are basically two parts of the disease that it's used in. One is what's called adjuvant therapy, when what you're trying to do is prevent a recurrence after a surgeon has done a resection of the colon. And that's really preventive chemotherapy. As they say, you're taking somebody who has a high risk for recurrence, and by giving them chemotherapy, typically for six months, you decrease it.

The other area, now, that's evolving quite quickly is the use of chemotherapy in patients who already have metastatic disease. In these patients, what you're trying to do is to reduce the metastatic disease, palliate them, make them live longer, decrease the symptoms due to the cancer.

More recently, we've become very interested as we have newer agents that are more effective in reducing the disease to the point where it might be surgically resected. Where a surgeon may be able to take cancer out of the liver and render the patient free of disease.

DAVID R. MARKS, MD: So is there any guideline as to what stage of disease the person has to be in to have chemo?

JOHN MacDONALD, MD: If you look at what's generally accepted in adjuvant therapy, everybody agrees that in Stage III disease, and that means the colon's been resected, and when the pathologist looks at it, the lymph nodes show some evidence of metastatic disease, there's no question that those patients benefit from the use of chemotherapy after resection. It decreases the likelihood that they're going to recur, and improves their overall survival.

The other group are patients with what's called Stage IV disease, which is metastatic disease. Again, you're treating them to reduce the disease, reduce the symptoms. And, potentially, with some patients, with a fraction of those patients, to eventually be able to surgically resect all the disease they have.

DAVID R. MARKS, MD: From a surgeon's perspective, what role does chemotherapy play in your management?

MICHAEL LIEBERMAN, MD: In terms of the peri-surgical management of patients with colorectal cancer, very useful techniques to make the tumors more amenable to resection, particularly in the rectum, have utilized both the combination of chemotherapy and radiation therapy prior to surgery. And then we would follow up with resection.

There's been some association with sphincter salvaging surgery by utilizing this technique for rectal cancers. And also downsizing the tumor, making it more amenable to a complete resection when it's in the rectum.

DAVID R. MARKS, MD: So it gives a person a greater chance of being cured with surgery?

MICHAEL LIEBERMAN, MD: Of resectability, and of functional improvement, by being able to preserve their sphincter, and give us a negative margin. So we've used that as a useful technique for rectal cancer. We've also seen utility in utilizing chemotherapy following liver resection for metastatic disease from colorectal cancer, and there's been some nice work that has demonstrated an advantage to adding chemotherapy delivered through a continuous pump placed in the operating room, at the time of liver resection.

There's some very interesting modalities, where we're interacting as a team, both the surgeon, radiation oncologist and the medical oncologist, in taking care of patients with this disease.

DAVID R. MARKS, MD: What are the agents that are being used?

JOHN MacDONALD, MD: The agents that are used, the main agent is an agent called 5FU, which has really been around for over 30 years. We know how to use it differently now. It's also now being used in combination with some newer drugs.

In the last 10 years, we've had several newer drugs which are really effective. One is called Camptosar. The other name is irinotecan. The third name for this drug is CPT11. But the combination of 5FU with this drug has almost doubled the response rate, seeing an improved survival. So that's been a real leap forward, as it were. Another drug is called oxaliplatin, which is experimental in investigational treatment, but is really quite valuable, and is going to be very useful.

Now there are even some oral chemotherapy agents. One called Xeloda, another called UFT, which are effective in colon cancer.

DAVID R. MARKS, MD: Are there any other agents that are coming down the road that may be even better than what we have?

JOHN MacDONALD, MD: I think one of the things that's been intriguing about colorectal cancer is, we understand more about the molecular genetics of this malignancy than almost any other human malignancy. So what we've been able to do is, we've been able to target the differences, the molecular differences between normal cells and colon cancer cells, and we're beginning to look at agents that affect that.

For example, agents that inhibit the epidermal growth factor receptor. There's a monoclonal antibody called C225 which is of interest. There are molecules, small molecules that inhibit the way this epidermal growth factor interacts with the colon cancer.

There are agents that inhibit the ability of the colon cancer to develop new vascularity, new blood vessels. These are called anti-angiogenesis strategies. There are a number of agents out there in clinical development, which are of real important and will be clinically available to many oncologists and combined modality surgical oncology, medical oncology, radiation oncology teams in the near future.

DAVID R. MARKS, MD: How does a patient find out about clinical trials that are ongoing right now? If they want to get involved in them?

JOHN MacDONALD, MD: One of the ways is to look at the cancer centers. Cancer centers in the United States participate in many national clinical trials, and all the cancer centers also have their own menu of local clinical trials. Certainly the National Cancer Institute has websites, and has information. The PDQ database, for example, which will allow people to know what clinical trials are out there.

And I think the other message is that clinical trials are frequently the best treatment for any cancer, because you're getting an opportunity to be involved on the cutting edge of what's out there.

DAVID R. MARKS, MD: Okay, good. We'll end it on good news. Thank you both for being here. Thank you for joining our webcast. I'm Dr. David Marks. Goodbye.

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