PSA 1 month after SBRT

[thatsnotme]

67 yo with Gleason score 7 localized prostate cancer.

I completed high dose SBRT a month ago and just got my first PSA results. My PSA dropped from 10 pretreatment to 7.1. I was expecting a much greater decline. I see the Dr next week. Should I be concerned that the the decrease is not more?

[GP24]

You could get a PSMA PET/CT to see if it is really localized.

[Jpl506]

One month is too soon to begin checking. You should wait at least 3 months. SBRT has a median time to PSA nadir of 30-36 months and it can bounce around for a while following treatment. The ride can be quite unsettling at times but it’s a marathon not a sprint.

[Tall_Allen]

You should not be having a PSA test at only one month after SBRT. It is inconceivable to me that any competent RO would ask for this. 3 months is standard for the first one.

[Wloi in reply to Tall_Allen]

Hi, Tall Allen and all, I were to have my first Eligard shot yesterday after my left Pelvis radiation 3 months ago but I was shocked to see my PSA has increased by 0.04 to 0.22 as compared to my 2nd month PSA which was 0.18 (before radiation, PSA = 0.48). My doctor has arranged a PSMA scan next week to check if there are new metastasis area (it is suspected maybe the pelvic bone near the left side lymph nodes). My first Eligard shot was also re-scheduled to next week after the PSMA scan.

Any thoughts about the PSA increase while comparing 2nd month and 3rd month PSA after radiation? The only difference as compared to all my previous blood drawn is that I have a gym and sauna session right before going for the 3rd month blood test. I thought that it should not have much impact since I do not have the prostate anymore. Many thanks!

[Tall_Allen in reply to Wloi]

This is a totally different situation from the OP.

[MateoBeach in reply to Wloi]

if you are under hydrated after workout and sauna it will significantly raise PSA value due to concentration. Rehydrate before lab tests and draw at same time. Check hematocrit to verify.

[MateoBeach in reply to MateoBeach]

Or just weigh yourself.

[Wloi in reply to MateoBeach]

Thanks. MateoBeach,

I am quite shock with the 3rd month PSA test results which I have expected further drop as my 2nd month test result was quite good (more than 50% drop). I asked my doctor to give me the shot at the appointment. However, he said let's have another PSMA scan to see how things have been progressing and see if further radiation is required before starting Eligard (1 week later) since the last scan was in Jul22. I concur with you that dehydration might be the cause of PSA rise and I also read that PSA bounce might be another reason as dead prostate cancer cells in the blood stream can cause temporary PSA rise.

I am now 50-50 on the next PSMA scan results, whether I should be happy to have a clean one or some new spots revealed.