Last week I finished 38 x-ray treatments on the Varian Linear Accelerator with IMRT for my prostate cancer. This device uses a variable leaf collimator for continuous dose adjustment as the beam rotates around the patient. Each treatment is preceded by a CT scan with a built in CT scanner mechanism on the accelerator. This is performed for purposes of alignment of the target area to the beam which rotates about a fixed axis, coincident with the center of the target.
Along with the 76 Gy of x-ray therapy is hormone ablation with Lupron. The standard treatment for advanced prostate cancer, Gleason 8 in my case, is hormone ablation and radiation therapy to the prostate.
Initially, the trick to impeding the growth of the cancer is to suppress testosterone which is needed for reproduction of the cancer cells. The pituitary controls the signaling for testosterone secretion from the testes. The adrenal glands secrete a small amount of testosterone as well. Lupron suppresses the signaling by the pituitary gland. This is effective for a period of time, perhaps as long as 24 to 36 months.
Eventually the cancer becomes resistant to this approach and enters the so-called refractory or castration resistant stage. In response to the lower testosterone titer in circulation the cancer cells produce more testosterone receptors, called AR for Androgen Receptor. The number of AR’s multiply by 3x to 5x, increasing the sensitivity of the cells to what little testosterone (or dihydrotestosterone) there may be in circulation.
Blocking the androgen receptors is an approach to treating castration resistant cancer, but it does have limitations. This will be explored in a later post.
An observation from a patient’s perspective. Insurance will generally not pay for off-label or experimental therapy. So unless the patient is self-insured, the treatment profile will follow the board approved protocols for a given diagnosis. This isn’t a bad thing, but often a medication or other treatment will show effectiveness in other applications. While the doc has some discretion here, the insurance company may not approve payment. And, they may decline to pay months down the timeline when their internal review staff have had a look at it. They make their profits by declining services, not offering to pay for it.
Initially I had hoped for the possibility of participation in a treatment study if this disease went south, as it is likely to do. What I was told is that because I have had 2 cancers, throat and prostate, I am almost certainly disqualified from participation. This was disappointing but I understand the reason for it. Even so, I am barred from a Hail Mary pass down the road.
So, what now? Well, it is watchful waiting. While PSA numbers are given less importance in checkups for ordinary patients owing to the history of overtreatment, for a post-treatment Gleason 8 patient like myself, the PSA number is a direct indicator of disease progression. Once the disease becomes castration resistant, I suppose that some kind of AR therapy is next. The docs have been evasive when asked. Apparently there are several paths available. But I suspect they would rather the patient focus on the present and not the damaged bridge miles ahead of the train. We’re all headed for that bridge, it’s just that some are further up the tracks.