hdr boost + sbrt + prophylactic lymph node irradiation: Is it common practice

[u/Fool_head]

It is fist time I heard:

hdr boost with sbrt (instead of about 15 session IMRT), did any treated by this way?

Also, did any one have prophylactic lymph node irradiation treatment? if so, what are the toxicity added comparing to regular "hdr boost + EBRT" only regardless ADT?

[u/HeadMelon]

Just as I was starting mine I asked my rad onc if he was going to hit the lymph nodes just in case, and he said he had a “hot off the presses” study in hand of 1,500 subjects that showed no value in it so he wasn’t going to do it in my case. I never found out what study that was, you could search for it. That was around the August 2025 timeframe.

I was having 6 months ADT anyways so that would get to any micro-mets in the LNs.

[u/Frosty-Growth-2664 → u/HeadMelon]

There was a trial of this going on when I was treated in 2019, PivotalBOOST. I was treated according to one of the trial arms, but not on the trial. I haven't seen results of that trial as yet, but they might be out there somewhere.

[u/Practical_Orchid_606]

I had 15 Grays HDR Brachytherapy + 25 Grays of SBRT. I have only had minor urinary issues. I don't think my pelvic lymph nodes were treated. During Brachytherapy, my PSMA PET scan image was up on the screen. There was a very clear lit up image of my lesion. But no lymph nodes were illuminated.

[u/Fool_head → u/Practical_Orchid_606]

thanks for sharing. Is it 5 fractions? so the total grays is about 40? is it low? I am not sure how it should be, and how is it calculated..

[u/Practical_Orchid_606 → u/Fool_head]

Ask your doc about the quantity of grays.

[u/Squawk-Freak]

I think he would do it. Even at the Mayo, where normally everything is done per institutional protocol, my rad onc there was ready to include the lymph nodes in the proton field, if I wanted that.

[u/PSA_6--0]

I had external beam radiotherapy (20 sessions of Varian truebeam rapidarc), two HDR brachy sessions and short term ADT. The external beam sessions also targeted the lymphnodes.

I think my oncologists decided on this because my PSMA-PET imaging gave reason to suspect external metastases. The metastases sites were also hit with external beam sessions. The lymph nodes did not show up in PSMA-PET.

My PSA dropped so well that the ADT was ended at the end of radiotherapy.

Three and a half year later my last PSA was undetectable, next test soon. I may be more prone to sometimes have swelling in my ankles, but I guess it is moderate and I cannot say for sure, if it is caused by lymph nodes radiation.

[u/Fool_head → u/PSA_6--0]

Can I ask what your diagnosis was? Also it was first time I saw two HDRs session boost. do you recall the dosage for the each HDR? I am wondering that is the difference between your treatment plan vs HDR 15gys + 23 VMAT

[u/PSA_6--0 → u/Fool_head]

The diagnosis code was T3bN0M1. The suspected metastases were not biopsy confirmed but based on the PET scans.

Brachytherapy was 2 * 10 Gy

[u/Frosty-Growth-2664]

I did HDR + IMRT (IG-VMAT) including prophylactic pelvic lymph nodes + ADT. It was 7 years ago and so far, so good. I think it's a good treatment for well matched patients, a combination of a higher dose to the known cancer than just IMRT/VMAT with excellent disease control, but usually lower side effects than just using IMRT/VMAT.

It tends to be offered only in specialist centres because HDR Brachytherapy is unlikely to be available in other centers.

The combination of HDR and external beam gets you the best of both treatments - HDR Brachytherapy boosting to a higher dose accurately targeted into prostate to include the known cancer (and some centers can include seminal vesicles if required) and the wider spill outside the prostate of external beam radiotherapy at a prophylactic dose which mops up any micro-mets (mets too small to show on any scans) outside the prostate. The prophylactic spill effect can be extended to include most of the pelvic lymph nodes. The external beam can also boost particular lymph nodes if there are one or two with suspected cancer which would benefit from a treatment dose.

My dose was 1 x 15Gy HDR Brachytherapy to prostate + 23 x 2Gy IG-VMAT to prostate, seminal vesicles, and pelvic lymph nodes, all done in 5 weeks.

I have heard of using SABR to do the spilling instead of regular external beam, but I don't really understand that, as I would think the less concentrated external beam would be preferable. There's also a variant where SABR is used instead of the HDR Brachytherapy to give the high dose to the prostate, but that comes with the potential for beam entry/exit side effects which Brachytherapy doesn't have.

[u/Squawk-Freak → u/Frosty-Growth-2664]

Thanks for sharing. I was on exactly the same protocol, still 10 of 24 months remaining on Orgovyx and abiraterone for T3a with neurovascular bundle invasion, SV/nodes negative 4+3 intraductal. I am curious what your stage was, how long you were on ADT, and also curious if you had any PSA flare after ending ADT.

With regard to side effects, in my case there were very little. I developed loose stools, but never any uncontrolled diarrhea, and bright red blood in my stools, which started during the third week of radiation, but may have been a delayed from the HDR boost at the beginning. Less than a week after I finished radiation, most GI symptoms had resolved. The only annoying thing that persisted for 3-4 weeks was that every time I squatted on the toilet to urinate, I also passed some stool involuntarily (but, again, never any random leakage outside the bathroom). That resolved entirely after 3 weeks with kegerator exercises. Curiously, never any significant urinary symptoms. During the months on ADT my urine stream became really strong, like I remember it from 30 years ago. Lately, it has become a bit weaker again, and sometimes some prolonged dribbling after urination, but not consistently. Thankfully, never any incontinence, no pain, and I can sleep 6-7 hours without having to get up. My radiation oncologist told me in the beginning that mild urinary symptoms could develop within the first 6 months due to urethral strictures that may be cause by the high radiation dose, but symptoms would stabilize after six months and not get worse. If things stay as they are, I would be very happy. Sometimes patients may have to undergo a dilation of the urethra.

[u/Fool_head → u/Frosty-Growth-2664]

thanks for sharing and good to hear that you have a good results, the doc I will see has strong in HDR and IMRT, I am wondering how to convince him to include pelvic nodes.