Wednesday, December 5, 2007

Chemo Catch-22

A friend of mine went to a chemo session with me last week and had some questions about my treatment. I thought I’d post it on my Blog because several other people have asked me similar questions. I though this would be of special interest to my fellow breast cancer patients.

Question: When you did your last MRI they said that a lot of the tumors had either disappeared or got smaller, so after your last chemo treatment, why do you have to wait 4 months to have another MRI? Is the chemo so long-living that it will take up to 4 months to take effect? Why can't you have your MRI in say, 1 month after today or 6 weeks after, then you'll see that there are only tiny little dots left, (if any) and then blast them again with a day's chemo? I don't understand the delay. Is it because you are having the Herceptin? But the Herceptin doesn't blast the cells, only acts as a buffer, right? So surely it would be best to eliminate all those cancer cells for good, then have the Herceptin, when you know they have gone, because otherwise the cancer cells can replicate and you won't even know. I'm confused. Why don't they do the scan sooner than 4 months?

Answer: I’m getting the MRI for the brain only and the PET/CT for the entire body. The MRI just shows the anatomical, physical view. A PET/CT scan shows a metabolic view. That means an MRI shows what’s there, e.g. an abnormal growth, while a PET/CT scan shows what’s happening, e.g. cancer cells feasting on sugar and rapidly growing and multiplying. So a PET/CT scan can show more than an MRI. It can pick up abnormal cell growth before the cells become large enough to become a visible tumor.

But even then, the PET/CT won’t pick up anything smaller than a pea. No scan can pick up microscopic disease. This is why doctors never say a patient is “cured” of cancer. They say there is “no evidence of disease”, or N.E.D. There is no way to tell if you’ve eliminated the cells for good. Ever. Cancer cells can lie dormant for years and years and one day, the right set of conditions will come together and those cells will become active again. This is why diet, exercise, and avoiding toxic chemicals in the environment are so important. You can never know what will trigger cancer cells to reactivate. What we DO know, however, is that many of the foods we eat and the chemicals we expose our bodies to provide stimuli for cancer cells to grow.

I still need to get an MRI of the brain, however, because for some reason, PET/CT scans miss some brain tumors while MRIs pick them up. I haven’t found a satisfactory explanation of why this is, so if any of you find one, let me know.

They can't do the PET/CT scan so regularly because it's radioactive. To do the scan, they inject a radioactive glucose solution into my veins. Too much of that and I'll develop MORE cancer. It's a real Catch-22. I need to have these radioactive scans to help me fight cancer, but these scans in turn give me MORE cancer. We have to weigh the risk of more cancer against the risk of dying of the cancer I already have.

I can't have non-stop chemo because then the chemo would kill me. We need to give my body a chance to recover from the chemo before we zap the cancer (and healthy) cells with more chemo. Another Catch-22. The chemo that can extend my life can also kill me. You see why oncologists have such a hard job? They have to find just the right chemo to save the patient without killing him. In fact, some people believe that cancer patients die from the treatment, rather than the cancer. There’s no way to prove it one way or the other.

Herceptin works in two ways: 1) It slows down or stops my particular kind of breast cancer cell (HER2+) from growing, 2) It tells my immune system to target my HER2+ cells. So Herceptin doesn’t directly kill the cancer cells the way chemotherapy does. But unlike chemotherapy, Herceptin is fairly targeted so it doesn’t damage my healthy cells as much as chemotherapy does. That’s why I can and will be on Herceptin for the rest of my life.

Thanks for asking the question. Please ask more questions, about anything at all.

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