Can you receive additional proton treatments years after radiation?

Someone came into this forum a few months ago and talked about getting proton radiation after having a lifetime of radiation. They said it was possible and is done in some medical Centers.

Not sure if he’s going to and talk about it, Just wanted to bring it up so you know it can be done some places.

If you’re not talking about proton being done in exactly the same place it was done before then that’s no big deal.

The answer is yes (maybe). I never use the word “cured” (even for myself at 5+ years post-proton radiation with no evidence of disease).

Key question is did you use a rectal spacer for your initial radiation treatment?
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Dr. Rossi has a lot of information about proton in his portion of this 2023 Mid-Year PCRI conference: https://www.youtube.com/live/WTqPnSRYtW4
—> Starting at 3:38:45

He speaks about “proton after proton” during the Q&A at around timestamp 4:53.00.

Q&A session: a lot of interesting topics:
—> 4:25:00: Proton & Insurance
—> 4:30:45: Proton SBRT
—> 4:34:30: Proton & ADT
—> 4:36:55: Proton & Supplements
—> 4:39:00: Proton & Diet
—> 4:40:00: Proton & Repurposed Drugs (Statins; Metformin)
—> 4:42:00: Proton & Post-Treatment Side-Effects Urinary
—> 4:46:00: Proton & Hyperbaric Therapy
—> 4:48:15: Proton & Pre-Existing Bowel Issues
—> 4:49:40: Proton & Hydrogel
—> 4:53:00: Proton & Re-radiation
—> 4:56:30: What happens to the prostate?
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Interesting. Never heard of this. I’m curious since I had Proton therapy. When you say in the same location, I thought my prostate was completely radiated. How does protons in the same place (as the previous lesions) become no big deal. Wouldn’t that be anywhere ratiated as well? Not sure wyat your mean Jeff.

I believe there are varying opinions on this. I had 20 sessions of IMRT (photon). 8 months later, PSMA PET scan showed increased uptake in a portion of my prostate. I asked my RO if it could be radiated again. A flat "no" was the answer. "You received a lifetime dose"

RO left the practice and I asked my new RO the same question. "While we don't like to, in some cases it can be done, however, I wouldn't even consider it until 3 years after the initial treatment since side effects can take that long to appear." So, the answer I got was a definitive maybe. This was with photon though. Don't know if proton makes a difference.

@robertov What external radiation (both photon and proton) does is to damage DNA at the cellular level. (See attached graphic.)

External radiation doesn’t simply “radiate the prostate,” it damages cellular DNA which prevents prostate cancer cells from multiplying. Cancerous prostate cancer cells do not have healthy DNA repair mechanisms, and over time they die off (which we observe as PSA decreasing).

Non-cancerous prostate cells are damaged as well, but they have healthy DNA repair mechanisms and can (usually) repair the radiation-induced DNA damage. They survive external radiation treatments and continue producing PSA (though at low “new normal” levels).

This also is why it’s helpful to maintain hormone therapy for some time after radiation treatments have ended. Radiation damage to prostate cancer cells’ DNA can continue long after the radiotherapy itself has been completed. So by keeping the androgen receptors inhibited or suppressed by hormone therapy, you can suppress that DNA repair mechanism for months. This is why ADT is a very important component to kill prostate cancer cells.

@brianjarvis
Thanks Brian for explaining this since it is often confusing for members to understand the whole process of how RT and ADT work together and work over extended period of time.

There is also very often confusion about proton and photon and sometimes members think that proton is somehow "milder" radiation but it causes the same damage , it is just more precise - it does less damage to non-targeted areas around. Radiation is radiation and many side effects are seen years down the road, unfortunately. 😟

@mjp0512 Dr. Rossi has a lot of information about proton (& photon) radiation in his portion of this 2023 Mid-Year PCRI conference: https://www.youtube.com/live/WTqPnSRYtW4

He touches on re-radiation at about timestamp 4:53:00.

@brianjarvis = Thanks, Brian!

@surftohealth88 Actually, both “radiation is radiation” and “many side effects are seen years down the road” need further explanation.

Photons and protons are as different as night and day.
> photons are massless packets of electromagnetic energy (like X-rays); photons lose energy continuously along their entire path.
> protons are heavy, positively charged subatomic particles; protons travel a specific distance, then create an intense burst of energy right at the end of their path.

The practical application of these concepts is significant.
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As for “many side effects are seen years down the road” —> Remember that what radiation doesn’t hit, it won’t affect. Much planning should be taken not to overshoot the prostate in order to avoid hitting nearby otherwise healthy tissues and organs (i.e., minimize entry-dose, scatter, and exit-dose). By applying radiation precisely and accurately, there should be no side effects seen years down the road.

Below is an article I get from a site that sends me frequent medical information. It about Proton Therapy. In a nutshell they say: For prostate cancer, however, the most important question has never been whether proton therapy is technologically impressive.

The question is whether patients experience better outcomes.

The latest evidence suggests that for most men with low- and intermediate-risk localized prostate cancer, the answer is probably no.

It's pretty long and most way over my head, but some might find it interesting??
https://www.medscape.com/s/viewarticle/proton-therapy-prostate-cancer-what-should-clinicians-do-2026a1000m94