Gastrointestinal cancer-10-Colon

GASTROINTESTINAL CANCER PART-10

Welcome to the tenth part of educational series on GastroIntestinal Cancers. We learned in part 9 about treatment of stage 1-3, role of pathologist, chemotherapy,newer medicines for colon cancer.

Question: Now Dr. Chiragbhai, what about the stage 4 colon cancer? What palliative treatments are available?

Answer: First of all, let me remind you that colon cancer is one of the few cancer types where cure is possible in many patients, even in stage 4. This is nearly impossible in most cancer types.

Que: That is amazing. How do you do that?

Ans: Well, majority of metastatic disease in colon cancer is confined to liver, lung, peritoneum. Especially at relapse, most patients have only liver metastases. And this i.e. liver metastases are frequently amenable to complete resection. At presentation, about 10% patients have resectable metastatic disease, but the percentage is much higher at relapse.

So, if the patient has resectable disease in metastatic sites and primary, they should all be removed either in one operation or in two stages.

Que: Do you mean that all such patients can undergo surgery, and how many are cured?

Ans: Of course not all patients are resectable. And there are strict criteria for selection, since this is a major surgery.

First of all, R0 resection i.e. ability to remove all gross disease, should be possible at all disease sites. Debulking has no role. Patient fitness, surgical expertise for liver resection, and ability to manage postoperative care are also important. Disease should not be a rapidly growing one. PET scan is useful in determination of all disease sites, to avoid unnecessary resections, especially at first presentation.

About 30% of these patients are cured after such a surgery i.e. achieve a 5 year survival. This is great compared to most metastatic cancers, where 5 year survival is less than 5%.

For patients with borderline operability or clearly inoperable disease, chemotherapy preferably with a monoclonal antibody(bevacizumab or cetuximab) should be given.

23-40% (in different published series) of such patients can be converted to operable disease. Such patients frequently achieve a prolonged survival.

In fact, systemic therapy has become so effective and with so many options, that even without operation, a number of patients now survive for up to 3-4 years.

Que: This is very interesting and heartening to note that one can now cure or control such advance disease, even in stage 4.

What about certain genetic tests you had mentioned, in part 8?

Ans: Yes, this is also very interesting, since we now have ability to predict what medicine will work for which patient or tumor, based on certain tests. Something similar to antibiotic susceptibility test for various bacteria. One example is: cetuximab is a drug that works in colon cancer only if patient’s tumor has a wild type K-RAS gene i.e. if patient’s tumor shows mutation, one should not use this drug. There are few other examples which we can talk about at some other time.

Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 98243 12144, 98988 31496

Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com

Shyam Hem-Onc Clinic. 402 Galaxy, Near Nehrunagar Circle, Ahmedabad.