Wednesday, 25 May 2011

Prostate Cancer Radio Therapy


D day was here, I had tried in vein to delay the inevitable. I had written to the surgeon twice and he had responded both times by calling me back on my mobile. The results of these conversations were that I was taking the best possible course of action for someone in my position. It just seems a shame that I have to endure this primitive treatment probably nearing the end of its useful life. Radiotherapy is used to kill cancer by zapping your cells with high energy gamma rays, which are high frequency photons or light. The light that we are aware of is visible light. The photons that make this light up have different frequencies associated with them; the higher the frequency the more energy the photon has. Red has a lower frequency than blue light and so has slightly less energy. Lower frequencies than red, like infra-red have even lower frequencies and energy. Higher frequencies than blue have greater energies the higher the frequency. The next one up is ultra-violet and then microwaves which we all can see have greater energy. Normal visible light can pass through air quite easily and some liquids but it’s not so good at passing through most solids. The higher the frequency the easier the photons can penetrate solids. Gamma rays having such high frequencies give the photons very high energy which can interact with water in your body knocking out electrons from these molecules causing them to be charged positive cations. These cations, when in the body are called "free radicals", notably hydroxyl radicals. Ironically, these are known to be dangerous when inside the body for causing cancer.

These free radicals are electrically attracted to your DNA inside your cells and sometimes cause the DNA to break. Because broken DNA would most likely inhibit protein production and cause cell death, we have evolved mechanisms to repair this DNA when only one of the two strands of the DNA helix is broken. If both strands were broken the cell would die. However, the repair mechanism is not 100% because we don't normally experience free radicals in huge quantities, so by introducing lots of them in the area where the cancer is growing over a long period of time causes the cancerous cells to gradually die. They will continue to divide, but more slowly as more and more cells are either deformed or die.

Cancers are made from undifferentiated cells, a little like stem cells so they are not specialised cells doing any particular function other than dividing. For this reason they usually divide and grow more quickly than normal differentiated cells just like they do in embryos or early life. However, undifferentiated cells are not as good as normal differentiated cells when it comes to the DNA repair mechanism, that's why this method has so much success and children are so susceptible to radiation.


Unfortunately, when you have prostate cancer like me, this organ is right in the middle of your body close to all your favourite bits. As there are no air gaps in your body, other than within your lungs, organs are tightly packed together. To be able to zap your bad cancerous cells in the middle of your body, the radiation must first pass through all your good cells and organs to get there. Also most the high frequency, high energy photons will pass straight through your body and could create free radicals on the way out as well as on the way in. For this reason, they split the beam of gamma rays into three and focus these beams where your prostate is. Another complication is that the organs in your body are not always in exactly the same place, they move around a little according to how much you have eaten and drank and if you have any trapped wind. For this reason they have to concentrate the gamma ray beams on your prostate with a 10 to 15mm focus greater than the actual size of the prostate so as to be sure to always hit it wherever it moves to at the time. This obviously means that you always have around 15mm of good tissue directly in the focused beam that will also be affected.

They locate where your prostate is initially with a CT scan prior to treatment, placing marks on your skin where the entry points of the photon beams will go. As treatment is over a couple of months they have to make these marks permanent by giving you small tattoos. CT scans work by penetrating your body with other high energy photons, but not quite as high power as gamma rays. These rays are called X-rays. These are also damaging to the body for the same reasons as the more powerful higher frequency gamma rays and so the nurses make a hasty retreat while the scan is in progress.

Claire came with me for my scan yesterday morning at 8.40am in Northampton. We were not that early because we heard, just before getting on the M1, that there was a hold-up so we diverted to the Northampton road. We followed the instructions regarding parking but found that car park 5 was inaccessible from the main entrance because of road works within the hospital grounds. We took the exit and drove around the outskirts of the hospital until we found another entrance but car park 5 was full. To avoid being late we parked on a bit of waste ground that said it was for the nurses. Once in the hospital, they took my details and gave us a parking permit allowing us to park in most of the car parks around the hospital grounds. Unfortunately this was too late for us as we had already been given a parking ticket.
 


When having the treatment they try to minimise the movement of the prostate by ensuring that the prostate is as close to the same position as when you had your scan. They like empty bowels but a full bladder which keeps your good bits which are likely to be affected as far out the way as possible. I hopped onto the scanning bed and they pulled my trousers and pants down and my shirt up. I was pleasantly surprised that I didn't hear any sniggering before they put the single sheet of blue paper over my embarrassment. They had a fiddle around and stuck 3 stickers where they guessed were the best areas to start the beams and disappeared from the room while I had my scan. Once they had returned a few minutes later they asked me to stay down while they took a "few measurements". Once finished I was let up only to be told that I had to come back for the whole process to be repeated again next week. The reason being that, although my bladder was full, my bowels were far from empty. I have been having a little trouble in that department ever since I started taking the drugs for high blood pressure. The joys of getting older.


Anyway, I need to come off these drugs until the treatment is complete; but on the up side, these drugs might help after my treatment as one of the worst side effects of the treatment is that you become much looser than you used to be before it. Maybe I will be lucky and the two will sort themselves out once I start taking the drugs again?


From the research that Claire and I have been doing, I believe that they are close to finding a modern treatment for both breast cancer and the very similar prostate cancer. Men develop prostates and women develop breasts; I suppose it’s fair that we both have similar problems with our unique bits. It just seems a shame that I couldn't delay this treatment for a couple of years to give them a chance to get these alternative, not so radical, treatments up and running.


I put a few photos of Claire and Ian around our new venture to pad it out.

1 comment:

  1. What an excellent explanation of how radiotherapy works. So basically you put your tackle in the microwave and hit defrost!

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