As I understand it, when PCa is treated with radiation therapy, the theory is cancer cells are more vulnerable to radiation because they divide more rapidly than normal cells, and they do not repair damage from radiation, while normal cells can.
The situation seems to be complicated if the person has BPH, since that would also contribute to the total PSA.
So the PSA comes from Normal prostate cells + BPH prostate cells, + PCa cells.
If someone started with a low volume PCa, that was treated with radiation therapy, verses someone with a large volume PCa that was treated with radiation therapy, wouldn't that imply the NADIR for the small volume PCa would be higher than the NADIR for a large volume PCa, since the low volume PCa also would have more normal cells, that would be less damaged than the radiation?
The reason I ask this question is because I see various places indicate that after radiation therapy the PSA should be less than a certain amount, but wouldn't that PSA value depend if it was a large volume PCa verses a small volume PCa?
It is easy to understand if the entire prostate is removed, because in that cause there should be zero PSA, unless something was left behind.
Any thoughts how they determine what the NADIR should be after radiation therapy?