Talk Cancer

Question:

Actually, there is a technique invovling phototherapeutic agents. These are ingested by the patient and remain inactive until irradiated by the appropriate wavelength of light. Since the inner portion of the body is dark, the drugs are only activated when laser light is guided to the affected portion of the body by a fiber-optic cable. Lasers, of course, are high-intensity light sources which can be tuned to specific wavelengths. In this case, a particular wavelength is chosen because the body is largely transparent to it (so it doesn’t burn good tissue) and because it will activate the drug molecule. The advantage to this technique is that the drug is harmless until until specifically activated by a physician, and other parts of the body are unaffected, since they are not irradiated or did not absorb the drug in high concentration. I was involved in this type of research about 5 years ago, and at that time is was still largely experimental. I don’t know how much progress has been made in the meantime. Gary Strahan, PhD – Hide quoted text — Show quoted text – A friend of mine has an infant niece fighting a brain tumor.  He mentioned that he had heard of a new surgery that involves treating the tumorous area with a chemical that only adheres to the cancerous tissue, and then destroying that tissue with a laser that only attacks the treated area.  He would like to find out more about this procedure, so I’m checking the ‘net. Cancernet didn’t yield anything (except for a good article on laser usage in cancer treatment in general.) Can anyone tell me more about this procedure, or where to find more information? Thanks, Geoff Bowerman Geoff, I’m not a doctor, but what you’re describing sounds like Boron Neutron Capture Therapy – might want to look for that on Cancernet or Oncolink.  Best of luck to the little girl. Kathy p.s.  BNCT does not use a laser.

Response:

I may be mistaken, but I think you’re referring to an experimental treatment in which the patient is given bromo-deoxy-uridine (BrDU) intravenously, which is incorporated into nucleic acids, especially in rapidly growing tumor cells.  The tumor is then hit with laser light in BrDU’s frequency of absorption.  I’m sorry that I can’t give you an actual reference, but I came across this a while back. — Medical Student Stanford

Response:

- Hide quoted text — Show quoted text – A friend of mine has an infant niece fighting a brain tumor.  He mentioned that he had heard of a new surgery that involves treating the tumorous area with a chemical that only adheres to the cancerous tissue, and then destroying that tissue with a laser that only attacks the treated area.  He would like to find out more about this procedure, so I’m checking the ‘net. Cancernet didn’t yield anything (except for a good article on laser usage in cancer treatment in general.) Can anyone tell me more about this procedure, or where to find more information? Thanks, Geoff Bowerman

Geoff, I’m not a doctor, but what you’re describing sounds like Boron Neutron Capture Therapy – might want to look for that on Cancernet or Oncolink.  Best of luck to the little girl. Kathy p.s.  BNCT does not use a laser.

Response:

– Hide quoted text — Show quoted text – A friend of mine has an infant niece fighting a brain tumor.  He mentioned that he had heard of a new surgery that involves treating the tumorous area with a chemical that only adheres to the cancerous tissue, and then destroying that tissue with a laser that only attacks the treated area.  He would like to find out more about this procedure, so I’m checking the ‘net. Cancernet didn’t yield anything (except for a good article on laser usage in cancer treatment in general.) Can anyone tell me more about this procedure, or where to find more information? Thanks, Geoff Bowerman

Hi,      I think what you are refering to is called Photo Acivation Therapy which is (as far as I know) being experimented on animals as a possible binary therapy modality for brain tumors.  In this modality some Iodinate or Brominated Uridine compound is used.  The compound get preferentially uptaken by the tumor DNA.  Then some low energy photon source, like a laser or synchrotron is used to treat the tumor.  The Iodine or Bromine in the DNA produces Auger electrons(I think), and this is what provides the local targeted therapy.      The above explanation is from my vague recollection and superficial understanding of this method.  If  you wish to get more information, you can send me email, and I will refer you to some people I know who work in this area.                     —- Nilendu

Response:

- Hide quoted text — Show quoted text – A friend of mine has an infant niece fighting a brain tumor.  He mentioned that he had heard of a new surgery that involves treating the tumorous area with a chemical that only adheres to the cancerous tissue, and then destroying that tissue with a laser that only attacks the treated area.  He would like to find out more about this procedure, so I’m checking the ‘net. Cancernet didn’t yield anything (except for a good article on laser usage in cancer treatment in general.) Can anyone tell me more about this procedure, or where to find more information? Thanks, Geoff Bowerman

It sounds like you are describing photodynamic therapy.  The treatment is based on sensitizing tumor cells with an agent that makes them susceptible to photoirradiation.  The trick, of course, is to find an agent which binds to cancer cells and not normal ones. One agent is hematoporphyrrin derivative (HPD)  It is absorbed by all cells, but normal cells excrete it better than cancer cells.  The agent is given systemically, and then some time later, the tumor is irradiated with light.  It can be a laser, but it doesn’t have to be.   I’m not an expert on photochemistry, but I think the HPD, after being hit by a photon of light, produces free radicals which are very toxic to the cell.  The best application for this therapy is tumors such as those in the esophagus or bronchus (breathing tube).  These can be directly visualized after photosensitization, and then irradiated with the laser.   It is important to mention that the laser is not the type which will burn the tumor as you would normally imagine; it is just a bright light which activates the HPD. Patients who have this treatment are carefully warned to stay out of the sun for up to 6 months, because they get a *nasty* burn from activation of the HPD deposited in the skin. I have heard of dramatic results with this treatment, but it is still experimental.  As you would imagine from this description, I see no way it could be applied to a brain tumor, since you would have a hard time exposing the brain tumor to a bright light! Mark Pleatman, M.D.

Response:

A friend of mine has an infant niece fighting a brain tumor.  He mentioned that he had heard of a new surgery that involves treating the tumorous area with a chemical that only adheres to the cancerous tissue, and then destroying that tissue with a laser that only attacks the treated area.  He would like to find out more about this procedure, so I’m checking the ‘net. Cancernet didn’t yield anything (except for a good article on laser usage in cancer treatment in general.) Can anyone tell me more about this procedure, or where to find more information? Thanks, Geoff Bowerman

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