Getting ready for radiation

This week we started down the path to understanding the radiation treatment coming up. When the tumor was removed it was not yet clear if it was cancerous. In fact, the previous needle biopsy had shown it to be benign so the surgeons really started out the surgery under the pretext that they were dealing with just a tissue growth that could be solid or cystic but not cancerous. Of course when the pathology report came back with the diagnosis, we then knew it to be cancerous. In a known cancerous resection the surgeons would have removed additional tissue around the tumor to make sure that as much as is possible all the cancerous cells were removed. In Tim’s case, the tumor was up against the skull and spinal column so there wasn’t much more tissue they could remove. After talking with the radiation oncologist, I don’t think there would have been much difference in the surgical approach even if they knew the tumor was cancerous.

So at this point the belief is that there are “microscopic” tumor pieces in the area of the surgery. These are the target for the upcoming radiation treatment. The process is quite fascinating as to how the treatment gets set up. The idea is to irradiate the tumor site and surrounding tissue/bone to create the margin that was not done during surgery and to also make sure that no other tissue receives radiation. The team creates a treatment plan that involves creating a 3 dimensional object to be irradiated. This process is called simulation and in addition to deciding on what exactly to irradiate, also produces the plan as to how to go about doing it. The radiation used in this case are x-rays and they will be administered from several (8-10) different angles, intensities, and beam sizes. In the volume to be irradiated, these different beams will become additive and outside of the volume they do not. So essentially in the volume, the full dose gets administered and outside very little. This is of course a computer assisted process, but it also takes a lot of consultation of experts to get right. It’s supposed to take 10 working days to compute.

The total dose will be in the range of 36-50 gray. They have to nail this down based on the continuation of chemo that Tim has chosen. It is likely to be at the lower end. Radiation measurements are weird I have to say. A gray is a measure of absorbed radiation and although related to an amount of energy, it is really energy absorbed per mass of tissue that is absorbing it. If your whole body took 36 gray you would be dead in minutes. But this amount of radiation will be administered over 5 weeks in daily sessions into a small mass. If the same amount of energy to be used for the localized area were administered to the whole body at once it would be a very small number of gray, about 0.15.

The other part of the simulation process is to make a thermoplastic mask so Tim’s head can be precisely positioned each time he goes in for the radiation dose. That was also done this week just prior to the most recent CT scans being done. With his head positioned on the CT table with the mask a new scan was done to assist in the simulation process. This scan will be combined with previous scans of the tumor so that the correct volume can be identified for radiation treatment. The mask making and new scan visit was pretty short, only about 45 minutes.

So now, it’s wait for the plan to be created. In about two weeks the sessions will start and last for about 5 weeks of weekday daily visits. These should take about 20 minutes in and out. Tim might be able to just drive himself over after school depending on schedules.
Next week is the first evaluation scan timeframe (3 months out). New scans will be done to see if any other cancer sites have developed. I think it will primarily be looking at the lungs to see if any cells have set up house there and started to grow. The expectation from the doctor is that nothing will be found but we continue to pray that that is the case.

--bob

A break from vincristine

I had wanted to write about the effects of vincristine since those side effects had started to be a major topic of discussion. Tim was getting more and more neuropathic. He had already developed tingling and numbness in his fingers and toes. Balance became difficult because the automatic small muscle impulses don’t happen anymore. And he had developed a pain symptom that felt like he was standing on gravel in his bare feet. This was not looking good.

But as has been his course, he has adapted somewhat to the side effects. After a few days of foot pain and some Tylenol, that has subsided. He still has no reflex action but we are told this is normal. And his gait has changed but in subtle ways. He has difficulty running and maintaining balance. But the good news in all this is that he gets a break from vincristine for a few weeks.

Yes, that’s’ right. The protocol has this built in break from weeks 10-12 where no vincristine is administered. So his last hospital stay really was a double whammy rather than a triple whammy. I think it’s good to be off the vincristine because he was getting worse being on it. The last hospital stay was also delayed so that Tim could go to homecoming and he was able to do exactly that. Other than being really tired afterwards and a scrape from running around in the park, he did really well. That took care of Friday and Saturday but then on Monday it was back in the hospital for cyclophosphamide and dactinomycin along with the “other” drugs (anti-nausea, a steroid and mesna). But no vincristine, yeah! He was a pretty tired pup from the weekend and hospital stay and so missed the early part of the school week.


At the end of that week was the marching band competition known locally as D-III. All of the high school marching bands compete at the BSU football stadium at 15 minute intervals. At the end while the judges tally their scores, the BSU marching band performs. It’s quite a show and a highlight of the marching band season. Tim was able to do his thing on the tuba but sitting in the pit as was planned. His school placed 3rd in their group and 3rd for the overall sweepstakes prize. Pretty good stuff and I’m glad he was able to help the band along the way.

Tim has also decided to stay on the cyclophosphamide for the duration (get off the clinical trial) because he is doing very well so far and feels that taking the more aggressive treatment approach is a better choice. The oncologist did say that if the treatment gets to be too much he would be comfortable with reducing the triple whammy sessions. So that decision is past us now.

Next up is the visit with the radiation oncologist to set up the radiation protocol which should start in a few weeks. But what’s really great is that he has no visit to the clinic this week at all and next week is just a round of diagnostic tests. It’s time to do a CT scan of the neck, chest and abdomen and of course get a blood count.

We’re hanging in there and time is moving along of course. We’re about one quarter of the way done already!

--bob