Tuesday, August 4, 2009

on tumor growth and radiotherapy

Mom's radiotherapy finished early today; she was done before I had even finished my previous blog post. Dr. Tonnesen is on vacation this week, so we met with a different radiation oncologist named Dr. Bajaj (pronounce the "j"s like the "j" in "jump"; the name is Indian, not Spanish). Normally, our consults with Dr. Tonnesen have been on Thursdays, but Dr. Bajaj holds his own consults on Tuesdays, which is why we saw him today before wheeling Mom down the hall to get some blood work done.

We asked Dr. Bajaj a few questions that have been nagging at us. One question, which has bothered me for a long time, is why the treatment for GBM is standardized if, as Dr. Fine at NCI noted, each GBM is actually unique at the genetic level. Wouldn't it be better to develop treatments tailored to the individual? Dr. Bajaj politely but bluntly noted that no such treatments have been developed (an answer that seems to sidestep the question), but he also said that the standard treatment today reflects the most current research on the subject. "What was novel three years ago is standard today," he said. His point, I think, was that it's those innovative treatments that help hone the way doctors deal with GBM in particular, as opposed to gliomas in general. As for the genetic uniqueness of the tumor, Dr Bajaj said, "At the end of the day, it's still a tumor," i.e., all tumors, no matter what their specific genetic structure is, will respond the same way to radiotherapy and chemotherapy administered at the appropriate dosages.

Science involves constant self-correction, especially in areas where rapid progress isn't easy. Fighting glioblastoma is one of those areas: scientists have been researching the cancer for decades, and still have found no hint of a cure. The introduction of Temodar as a supplement to radiation was considered a major breakthrough a couple years back because it extended the median life expectancy of GBM patients from a few months to a little over a year (we've been over those stats before, so I won't repeat them here). Tests are done on patients in clinical trials; the results of those tests yield statistics that allow doctors to have an ever more accurate picture of which treatment works, in what way, and for how long. The treatment Mom is receiving now is the current standard therapy for GBM-- i.e., it's the same protocol in all legitimate cancer treatment facilities.

We also asked Dr. Bajaj about the neoplasm (new abnormal tissue, i.e., the new tumor growth) in Mom's brain. We had learned a while back about the spread of the tumor from her left hemisphere across the corpus callosum to the right hemisphere, and we were unsure whether Mom's current radiotherapy was adequately covering the neoplastic tissue. Did the beams have to be recalibrated and re-aimed so as to target the new growth, or was this adjustment being made automatically as the docs scanned Mom's head during each treatment? I told the doc that I was unclear on how, exactly, the process worked-- were the beams narrow, almost like the coherent light of lasers, or were they more along the lines of a flashlight beam, easily spreading outward according to a "butter gun" spread pattern?

The doctor told us that the radiation covered 4-5cm more than the target tumor area, which was a way to catch more than just the principal cancerous masses. He showed us a printout of the beam coverage in Mom's case, and affirmed that the radiation beams were more like flashlight beams than lasers. In other words, the points of intersection between the beams were all rather large, irradiating a significant volume of the brain at each spot where the beams crossed. We saw for ourselves that a large portion of Mom's brain was thus covered.

This was, at least initially, reassuring. Dad and I had begun to worry that the new cancerous growths were somehow being missed, that the doctors weren't making adjustments to account for the tumor's progress. Instead, we've seen that radiation treatment tends to anticipate the tumor's progress by covering more than the main cancerous masses. Still, it was vexing to realize how much the tumor had progressed during the time that Mom was off therapy and on daptomycin-- a period of about eight weeks. Doctor after doctor had reassured us that we needn't worry about rapid tumor growth yet. As much as 6 months could go by before the question became significant, or so we were told.

But we've learned not to trust the doctors' reassurances when it comes to Mom's health. Better to assume that some form of Murphy's Law is always in operation: entire armies of microorganisms looking for any excuse to invade Mom's immune system, and/or a tumor that seems to be worsening faster than the standard predictive models can account for. In this case, Murphy's Law says that, if the docs claim that Mom's tumor won't show significant progress for six months, then it'll actually show progress in two. Dad and I have made arrangements to talk with Dr. Tonnesen about this early next week, when the doc is back from vacation.

In fact, we plan to hammer him with questions about this issue. What we still haven't established is whether the tumor's progress, as reported on the latest MRI paperwork, reflects rapid neoplastic growth or is merely a slow and steady continuation of what we had been informed of many weeks ago, back when Dr. Benson had first spoken to me during Mom's second hospital stay. A corollary question is whether the radiation has had much effect on the neoplasm since the resumption of Mom's treatment, or if it seems that the cancer is a juggernaut racing through Mom's brain. I hate to say it, but this is a practical question, because it affects how we make arrangements for Mom's future, and for our future without her.

So we came away from our two doctors' appointments with mixed feelings. We're reassured that Mom's skin is healing well, and it's nice to know that surgery and in-tandem therapy have done something to stave off the progress of part of Mom's cancer. We're also reassured that the docs are doing what they can to cover every part of Mom's brain that has been affected by the cancer. But we're still worried about where and how the tumor is spreading, and we'd like a clearer notion of the big picture: how rapidly is the spread happening, and how effective, overall, has the resumption of treatment been?

Mom got up a little after 7AM today. I'm guessing she didn't sleep that well, perhaps because of her aches and pains from yesterday's walk. She's been fast asleep almost since she got home from therapy. The contingent from church has been called off to allow her to rest. They can come by another day.

UPDATE, 4:59PM: A family friend emailed me a link to a NY Times article about clinical trials for cancer. It's a must-read for people who are interested in this subject. Significantly, the article briefly mentions my own concern when it says:

In most studies researchers have not accounted for genetic differences in tumors.

As cancer-fighting technology continues to advance, I can only hope that more individualized therapies will become available. Cancer is essentially a genetic beast; the battleground therefore lies at the genetic level.


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