Radiation is high energy x-rays. When you are depositing energy into a target with the latest technology, you’re able to kill off a tumor and you’re able to preferentially address a given region and to spare the adjacent tissues around that region. There are different types of radiation, but therapeutic radiation is high dose energy that gets delivered to ablate and kill off tumors.
The mechanism is that it’s damaging the DNA of a cancer cell. So when cancer cells try to divide, they die off after having radiation. Radiation works by killing off the cancer cells through damaging their DNA.
When cancer cells try to divide, which is all that cancer cells do, they essentially die off.
A common thought around cancer cells is that cancer cells divide and continue to divide because the DNA within them is different.
We have cancer cells throughout our lifetime and our body has a pre-programed way of killing off abnormal cells. The cancer cell is the cell that got away. The body did not realize it was abnormal and that particular cell continued to divide and continued to divide. So the normal process of the body saying, “This cell’s not behaving the way it should,” fell through the cracks.
The damage that the radiation performs on the cancer cell DNA is called double stranded DNA breaks. That’s a fancy way of saying the damage renders the cancer cell unable to continue to divide, and when it tries to, it dies off. Essentially, during radiation therapy, the cancer cells are dying off and the normal tissue is healing itself in between each of the treatments.
It’s not possible for the cancer cell to heal itself with the doses we’re giving.
Radiation’s been around for well over 100 years, and it’s not a binary thing where you turn on a switch and there’s radiation. You’re able to really modulate the doses and determine what doses to give, and to which areas you’re delivering it, with such accuracy you’re able to give the appropriate dose for the appropriate cancer.
Not every cancer requires the same dose, and not every normal tissue repairs the same way. Radiation oncologists have to memorize what doses every single structure in the body can tolerate, what percentage of whatever structure can tolerate with each dose, and that goes part into the training of being a radiation oncologist.
The tolerance of the rectum is different than the tolerance of the bladder. The tolerance of nerves is different than the tolerance of brain tissue.
Each of the organs and systems that we have in our body have a different ability to repair itself when it’s faced with high energy ionizing radiation. When you go outside get a sunburn, you don’t stay with that burn forever. Your body heals itself. When you have a cut, your body heals itself. If the cut is too big you need to have stitches. It’s the same sort of analogy that you would give with radiation toxicity or radiation healing. There’s a certain dose at which your body will be able to heal, and that’s really the skill of the radiation oncologist to paint the dosage just so to allow your healthy cells to heal while the cancer cells gets destroyed.