SIB: how is it different from SBRT boost?

[duckcalldan]

Basically the title. Now that my cT3b is, after PSMA PET scan revealed a sub-cm (7mm) pelvic lymph node lesion, cT3bN1, my agreed-upon RT plan (28 IMRT fractions to the whole pelvis, followed by 5 fraction SBRT boost to my prostate tumor) is in question. My insurance won’t likely approve any SBRT or brachy boost for node-positive PCa (though there are always appeals).

With that in mind, my RadOnc is proposing the same 28-fraction VMAT treatment but with a focal boost to prostate and affected node (70 Gy to prostate and seminal vesicles, 50.4 to whole pelvis and 66-70 Gy to the affected node). I am on Orgovyx and Nubeqa and will have 9 weeks of hormone therapy before RT begins, so the tumors should shrink considerably.

So…Simultaneous Integrated Boost (SIB): is there any disadvantage to that vs a SBRT boost from a curative standpoint? I know that cure is far from a given for N1 PCa but I want to be aggressive as I can early on. I’m happy to forego the SBRT (or brachy) boost if I will get an equivalent amount of radiation strength from my VMAT treatment.

My VMAT would occur locally (Tacoma, WA) and, if approved, I’ll go to Swedish in Seattle for SBRT with a RadOnc that works closely with Dr Meier, a CyberKnife expert.

Thanks to my fellow fighters. 💪

[Tall_Allen]

It's the same thing.

[NanoMRI]

I see in your bio that you considered RP - which I chose. After my unsuccessful salvage RT to prostate bed, I then chose to fight my remaining pelvic lymph node cancer with salvage extended pelvic lymph node surgery using the frozen section pathology method. That was nearly seven years ago and I carry-on with a most successful outcome.

[maley2711 in reply to NanoMRI]

Did you have whole pelvic RT, and when that failed the surgery?

[NanoMRI in reply to maley2711]

No, I chose to limit the RT to prostate bed. It was after the salvage RT nadir of 0.075 that I chose the salvage ePLND, based on the findings of the Ferrotran nanoparticle MRI.

[GP24]

If there is a positive node, there are usually smaller ones which cannot be detected yet. Therefore whole pelvis radiation is better for this situation, see this trial:

urotoday.com/video-lectures...

[maley2711]

The trials I have seen found SIB to give results similar to brachy boost, with perhaps even a more favorable SE profile. The local tumor must be located favorably...fortunately mine was , per my RO.

[Mgtd]

For what it is worth I had IMRT 25 sessions to prostrate and had the whole pelvic area done as a precaution. I had the same dosage as you posted.

I elected to do a total of 6 months of Lupron. Two before and 4 after after radiation.

Side effects were OK and I am now in that wait and see stage. I now get my PSA done every 6 months and I go back to my RO in January for a yearly follow up.

I have had a slight rise in PSA but nothing to be really alarmed about. Based on that my MO has me scheduled me for a blood biopsy test before my next appointment. I think she is curious if the 0.03 rise over the last year in PSA we are seeing can possibly be an early biochemical recurrence.

Honestly I maybe her personal test of the effectiveness of the blood biopsy test. I am more then willing to go along with her curiosity. Maybe just maybe we can get a head start on a potential recurrence.