Posted By: Anonymous IMRT vs.standard external beam rad - 07-03-2002 06:40 AM
After 10 hours of commuting and cancer center consultation, my mind is exhausted so I'm looking for help for this distinction.

My mother had her radiation consultation yesterday. After 5 doctors, we've finally found one who is willing to talk and wants to be as aggressive as possible. He made a comment that I don't understand. He said that since my mother has cervical lymph node involvement, IMRT would miss too much of the cancer and he feels standard radiation would be better. I have read many articles on the advantages of IMRT for advanced head and neck cancers so his statement puzzles me. Can anyone explain this to me?

As an aside, I asked about amifostine. He is against it because he feels the increased benefit is only about 1% of patients but more importantly he is afraid it protects too much of the tumor to the detriment of killing all of the cancer cells. In the scheme of things, I think this is the least of my mother's worries so I'm not going to press the isssue.

Thanks for any feedback.

Cynthia
Posted By: Mark Giles Re: IMRT vs.standard external beam rad - 07-03-2002 10:15 AM
Hi, Cynthia.

First, let me say that I'm not a doctor. Second, let me say that I have not received radiation therapy myself. But after I had surgery to remove a T2 carcinoma of the tongue, I consulted a radiation oncologist to see if she thought it would be useful for me to have follow-up radiation.

One of the many topics we discussed was IMRT (intensity modulated radiation therapy). Like you, I was very interested in the possibility of focusing the radiation on the cancer itself, and sparing the surrounding healthy tissues, and thereby avoiding the debilitating side effects. However, the radiation oncologist explained to me that IMRT was not really appropriate for my situation. Since I had already had the tumor removed from my tongue, the purpose of radiation therapy at that point would have been to kill any stray cancer cells that may have spread to the lymph nodes of the neck, not to kill a single tumor.

Upon further reading, I now understand the concept. IMRT hits the tumor at different angles, at varying intensity, compensating for the density of surrounding tissue. It is highly precise, and can achieve pinpoint accuracy, even "wrapping" around healthy tissues as it kills the cancer cells.

But remember, Cynthia, the human neck contains about 200 lymph nodes. If we know that cancer has spread to one or more of these nodes, or maybe we're not even sure, but only suspect it may have, where do we point the beam? It would be like watering a lawn by walking around with a watering can, searching for brown blades of grass, and watering only those. Not only would it take us forever, but we'd never be sure we found them all.

I've read that IMRT has been used most successfully in prostate tumors (spares the bladder, pelvic nerves and blood vessels), breast cancer (spares the heart and lungs), certain types of brain tumors, and certain types of mouth and throat tumors. The operative phrase here is "certain types". There may well be types of oral cancer that are amenable to IMRT. But once lymph node involvement is suspected, unfortunately, the area needs to be "sprayed" with radiation. It's the only way to be sure that stray cancer cells are effectively killed. And after reading the posts to this message board, I would never be willing to endure a radiation therapy regimen, unless I knew it was going to do the job.

You mentioned articles touting IMRT in cases of advanced head and neck cancers. I'm no doctor, so I can only guess at the reasons. One possibility is that the tumor is entirely localised, with no suspicion of any lymph node involvement. A second possibility is that the goal is palliation. In other words, a cure is not expected, but by destroying a specific tumor which may be impinging on nerves, blood vessels, etc. the patient will enjoy a higher quality of life. But these are only guesses on my part.

As far as amifostine goes, I am a bit surprised that your mother's doctor is not in favor of it. The radiation oncologist I spoke with could not say enough good things about it. She did point out, however, that it does not eliminate the side effects, but only reduces them, and that it's not for everyone. (There are some nasty side effects to the amifostine itself). I agree with you, that this may not be an issue worth pursuing. But if you still have questions about it, maybe you could get a 2nd opinion from another radiation oncologist.

Hope this helps. Best of luck to your mother and to you.
Posted By: Brian Hill Re: IMRT vs.standard external beam rad - 07-03-2002 06:03 PM
Mark's response is right on target, and his analogy of the grass is most appropriate. In very localized oral cancers IMRT is being used at some centers to spare the salivary glands and the thyroid from exposure. But those patients who meet the protocols for IMRT of oral cancers must not have cervical involvement.
Posted By: Anonymous Re: IMRT vs.standard external beam rad - 07-03-2002 06:49 PM
Thank you Mark for taking the time to explain so well the differences.

We just found out she will be starting twice daily radiation on the 15th along with concurrent chemotherapy. Then the fun begins. frown

Thanks again.

Cynthia
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