When to do 'advanced' tests?

[Proflac]

Hi All, At what point in the advanced Pca journey is a Foundation One liquid biopsy (or similar) a useful test to influence treatment decisions? My husband is still hormone sensitive - MHSPC (we think) and taking ADT plus Zytiga. The last PSA had increased from .92 to 1.3 from tests 2 weeks apart. That was a month ago and we now await results of latest bloods this week. It had gone to 1.1 a month previously and then dropped down, so we were hoping this might be just another blip. (still has prostate – see profile). If PSA is raised again however, then my feeling is that we need to think about taking some action. Not had a bone scan for a year, last CT was Nov.2020, Never had PSMA PET CT or any of the advanced scans. Germline saliva test showed no relevant mutations. Would a liquid biopsy to look at somatic mutations etc. be useful at this point in informing treatment decisions? Or should we wait? Ditto with PSMA PET CT or other advanced scan. We would have to self-pay for both (UK). Blood test for biomarkers should be easy to get, but will it be useful this stage? Costs are not a major issue for us thankfully. PSMA PET CT would have to be at private centre but could be arranged within a few weeks I think if required. Or would AXUMIN scan be sufficient if that was easier to access? Is there likely to be any actionable outcome from any of these tests at this stage? We are in the UK, so if relevant or considered helpful down the line, LU177 would be available theoretically. He has not yet had docetaxel (cancelled last year due to Covid) so I suspect that might be the next step at some point? Would any of these tests be of any utility in looking at that treatment option – or are they irrelevant to that decision? Not discussed as yet with the oncologist, but our consultant is of the opinion more generally that there is no point in doing tests if they wont change clinical practice – and I guess he is right! At what stage or PSA level (or some other marker?), would folks think that such tests would be a sensible way forward? Sorry for the long post. As a thank you, I offer this photo of the sunrise outside my house in Nottinghamshire this morning. Really lifted my soul.

[LearnAll]

With a man who never had Surgery ,Radiation or Chemo ...and has 100% intact prostate, the upper limit of safe PSA is determined by a simple formula....and that is;;...If his Prostate Gland size is 40 ml then the upper safe limit of PSA should be 4.0. Similarly, if Prostate is 30 ml in size, the upper safe limit is considered to be 3.0. This is according to a well known, prostate oncologist in USA.But with bone mets, just PSA is not enough to reach any decision...Bone specific Alk Phos must be checked along with PSA. If Bone ALP is below 20 mcgm/L , then no new mets are likely to be there.

If PSA is just dancing up and down between 1.0 to 2.0, I will only watch and enjoy the dance.

[dhccpa in reply to LearnAll]

Hope to hellck you're right about that.

Mine shrunk from 53 cc before starting Lupron to 18 cc 20 months later. PSA was 0.7 in October and November 2020 tests.

[GP24]

I think you should get the test early even though you may not need the results right now. It takes quite a while for the test to complete and this can turn out to be a long time at a later stage of the disease when you want to make decisions quickly because the PSA value increases rapidly. Also, the quality control of the lab prefers when the biopsy tissue is not old.

[Proflac in reply to GP24]

Thanks GP24. Do you mean get the liquid biopsy test early? We already have a germline test - with no actionable mutations in that. I dont think a tissue biopsy is a possibility at the moment.

[GP24 in reply to Proflac]

You had a germline test but you should also get a somatic test based on tumor tissue. A BRCA2 or 1 mutation can be detected in both of these tests independently. The somatic test is mostly done using the tissue from surgery which is still kept at the pathologist. This tissue will not change and the results will be same if you do the test now or later. It just gets a bit more problematic to analyse this tissue the older it gets.

I think Foundation One has a lab in the Netherlands where they can do this Foundation One CDx Test for you. Here are details about the test:

assets.ctfassets.net/w98cd4...

However, you can also simply ask the pathologist that you want your biopsy slides tested for BRCA2 or BRCA1 and ask him to send them to a lab in the UK which can do this test. This test is often done for breast cancer, so there should be labs in the UK which can offer this test and the pathologist will know where to send it.

You do not need this test now but if you can afford it why not get it while you have plenty of time to get it done? The results will most probably be required later.

[GP24 in reply to GP24]

The somatic tissue test can also be done from the slides of the biopsy before the radiation.

[Proflac in reply to GP24]

Thanks for your reply

[Tall_Allen]

Beautiful sunrise!

I agree with you and your consultant that there is no point to any testing unless a treatment decision would be changed as a result. If his PSA is pretty stable, there is no reason for action. If it begins to rise steadily, a bone scan/CT may show progression. When that happens, docetaxel is probably your best next step.

There's no need for a PSMA scan. You have no baseline, and it would undoubtedly show more cancer than the bone scan/CT - but what would you do with that info?

As for a biopsy of a metastasis, it may be a good idea if any metastases are large enough and in a convenient place to biopsy. First priority should be histology and IHC, then, if there is enough tissue, a genomic analysis. Genomic analysis of CTC and cfDNA can be done if a biopsy is difficult. Unfortunately, there aren't a lot of actionable mutations.

[Proflac in reply to Tall_Allen]

Thanks. Can you help me out with 'histology and IHC' He has a range of tests in the blood draw - is that what you mean? what specifically should we be monitoring in this regard?

[Tall_Allen in reply to Proflac]

Histology means they look at the cell types. Immunohistochemistry (IHC) reveals the proteins expressed by the cancer. They can tell a lot about the cancer using these tools.

[Proflac in reply to Tall_Allen]

Thanks for your reply. What kind of sample would we need for this?

[Tall_Allen in reply to Proflac]

Ask their pathologist.

[GP24]

If the CT showed lymph node metastases I would get a PSMA PET/CT now. This is the best scan currently. Unfortunately it will probably show many more lymph node metastases and maybe a few bone metastases. You can fight these with a Lu177 therapy or continue with Abiraterone and Chemo. My choice would be Lu177.

[Proflac in reply to GP24]

Thanks for your reply.