PET/PSMA scan results after 3rd LU-177. Should I go ahead with SBRT or complete 4th LU-177?

[bellyhappy]

PSA Marker came down marginally from 0.227 to 0.202 . Results of PET/PSMA scan today compare with scan on May 2021:

1. The previously noted PSMA avid sclerotic bone metastases demonstrate interval resolution of PSMA uptake. The current scan shows multiple non-PSMA avid sclerotic bone lesions, which are suggestive of treated bone metastases.

2. No definitive scan evidence of PSMA avid nodal metastasis is noted.

3. Small foci of mildly increased PSMA update are seen in both lobes of prostate gland, which show interval increase in uptake when compared with the previous scan.

4. There is interval detection of mildly PSMA avid right sacral sclerotic bone metastasis.

The oncologist and radiologist are happy with the effectiveness of the LU-177. But radiologist is suggesting I consider doing SBRT or IMRT to take care of the lobes of prostate gland and the right sacral sclerotic bone.

Looking for advice if I should go ahead and do the SBRT or continue the 4th infusion of LU 177.

[noirhole]

I would finish the LU-177 and then start the SBRT or chemo to target non PMSA tumors.

[GP24]

In Germany there is no fixed number of cycles. You decide based on a PSMA PET/CT if it worked well or not. So there is nothing to "finish". I would take a treatment break and get another PSMA PET/CT next year and decide based on that. You have to expect that there will be new mets then, so the radiation of the small tumor lesions currently visible will be not effective. Get another Lu177 cycle then.

[Tall_Allen]

Congratulations on the improvement! I agree that you should not have any further Lu177PSMA treatment at this time because there is not enough to treat. Further treatment will have high toxicity for you and little benefit. Give your kidneys a break from all that destructive radioactivity.

SBRT to the right sacrum in a single dose is worth considering. It's usually a safe spot to irradiate. I'm not sure if there is any benefit, but it couldn't hurt.

I'm not sure if there is any benefit to SBRT to the prostate, however. Two major randomized trials showed there was no benefit after multiple metastases have been detected. Also, the PET scan you had is notorious for false positives in the prostate because it is excreted via the urinary tract.

[MateoBeach]

There is no reason not to apply the law of diminishing returns in evaluating your situation. You may have already received the benefits it can offer. And further treatments may give more toxicity than benefits as you don’t have enough remaining PSMA avidity. Previous studies of SBRT to the prostate were not done right after hitting it with Lu-PSMA treatments. So the conclusions may not be applicable. “Evolutionary extinction” of cancer suggests a “first-hit” (the Lu treatments) followed immediately with a “Second hit” with another different treatment and not allowing it to recover. That could be the SBRT to the prostate and the bone met. Or it could be a round of chemo or other. This is routinely done and SOC in some other cancers like childhood blood cancers and can lead to cures. But it has not typically been tested in clinical trials in APC. Perhaps the surprising efficacy in the PEACE-1 trial may be due to this effect of combining treatments rapidly.

Personally I would favor the proposed SBRT for these reasons. And perhaps follow immediately with some chemotherapy. Best of luck. Paul

[slpdvmmd]

when I talked with Nat Lenzo in Australia he said they have a cohort of patients with combined sbrt and lutetium and he felt they were additive forms of treatment.

[Brysonal]

Our radio onco said PSMA PET scan was not used as the basis of the STAMPEDE trial data so ordered basic ‘stampede trial type scans’ which only picked up one bone met. On that basis she recommends treating the primary even though the PSMA pet scan had picked up 8. Good Luck

[Chewiemo]

are you hormone sensitive? I am and I’m about to have 6th dose. Psa is undetectable and bone scans show healing. I had Mets in spine, pelvis and ribs.