Where do (potential) future mets come from? Prostate? Or existing mets?

[rsgdmd]

So, I am de novo stage 4 with mets to 6 spots in different bones and have my last (6th) chemo scheduled in 3 weeks. PSA has dropped from 28.2 to just over 1 as of last week. Once 6th chemo is done, will have new scans done about 4 - 6 weeks later and meet with MO as to what's next.

I know situations such as mine are treated systemically; no surgery or radiation to prostate. My question is why not. If there are future mets, aren't they likely to come from the prostate itself, rather than from an existing met? If so, wouldn't reducing the burden of disease (via radiation) or removing the source (via surgery) be a positive? I understand there are risks involved with radiation and/or surgery. This is more of a theoretical question, at this point.

Thanks

[Tall_Allen]

"If there are future mets, aren't they likely to come from the prostate itself, rather than from an existing met?" No. And you put your finger on the reason. Spread from the prostate is only important at the very beginning. In fact, if there are more mets than 3 on a bone scan, treating the prostate (called "debulking") doesn't slow progression at all. Then met-to-met spread takes over. You also have many more metastases than just the ones you can see on scans.

prostatecancer.news/2018/09...

If you have a bad reaction to Zytiga, you can take Nubeqa.

[rsgdmd in reply to Tall_Allen]

Thanks, that's what I thought. Will be re-trying abiraterone, starting at 1/2 dose, after chemo is done and if still a problem, switch to daralutemide. I'm a good candidate for Keytruda with MMRd and MSIh and high TMB. Now, the question is might radiation therapy help make the tumor more "hot" for immunotherapy to possibly work better?

[Tall_Allen in reply to rsgdmd]

You don't want to incur the extra side effects from radiation for no reason. Chemo provides plenty of antigens.

But if you are MSI-hi/dMMR, there have been almost miraculous remissions with Keytruda. I'd discuss moving onto that immediately.

[rsgdmd in reply to Tall_Allen]

6th and final chemo coming up soon, then scans and then meet with doc. She's already talked about it.

[Soumen79 in reply to Tall_Allen]

Two questions TA -

1. What msi means for cancer aggressiveness?

2. Keutruda doesnt have any chance if msi is not high?

3. Is msi a progressive thing? Means in long run of treatment can it change?

[Tall_Allen in reply to Soumen79]

1. more aggressive

2. Very little effect with no msi-hi

3. Not progressive.

[Soumen79 in reply to Tall_Allen]

Thank you TA 🙏🙏

[Hidden]

My understanding. Micro-metastasis are shed to the vascular and lymphatic systems from any existing metastatic lesion or tumor. Once in their “network highway”, they look for a place to colonize and grow.

GD

[Rev214]

My thoughts exactly! It seems that once stage 4, only treatments aimed @ reducing pain by radiation is radiation even considered .

[Seasid]

I radiated my prostate very recently 4.5 years after my initial diagnosis as multi metastatic in my bones with more than 15 mets.

The RO ordered PSMA PET scan and CT with contrast and the SUV max value of my prostate was 14.

My therapy was and still is Degarelix injections only. I also had early docytaxel chemotherapy treatment 6 cycles.

95% of my prostate was full of cancer before radiation.

I had no visible mets on any scan.

My PSA was 1.5 and we decided to SBRT my prostate with MRI Linac 5 fractions 38 Gy.

After the 4th fraction my PSA dropped to 1.2.

I made this decision as I wanted to avoid local spread of my prostate cancer to my rectum etc. As my PSA was slowly rising from 0.2 to 1.25 in the last year and so. Therefore indicating CRPC.

I wanted to avoid the escalation of my treatment to chemotherapy, or Enzalutamide.

Chemotherapy is not good for you and Xtandi can breed out in 15% of people neuroendocrine cancer.

I also wanted to avoid side effects of the chemo and/or Enzalutamide and to save them for later.

I don't have side effects from the radiation and hope that everything will stay this way.

My biggest concern now is that I am osteoporotic now and I have to see soon the endocrinologist.