First PSA test after IMRT

Just completed a course of 43 IMRT sessions in late November. First post-treatment RO appointment is next week. PSA test yesterday and online results today show no change. 3.1 pre treatment and 3.1 post treatment.

Online research suggests many ROs obtain first PSA 3-6 months after the completion of treatment.

Since I don't meet with my RO until Monday, I'd like to know if this non-reduction in PSA is significant and what is the purpose of obtaining a PSA only 5 weeks after the completion of treatment.

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age 63
3/1/2015 PSA 1.9, nodule noted on prostate
5/20/2015 biopsy (15 cores), 3 cores were positive. Nodule: Gleason 3+3 in 1 of 3 cores (1mm) and right mid: 3+4 in 2 of 2 cores (4mm)
7/20/15 Bostwick - Nodule: Gleason 3+3 and < 5% of the sample; and right mid 3+4 and 10% of the sample and Gleason 4 comprising 10% 0f the cancer
7/22/15 Oncotype DX - GPS 14 , 11/2/2015 PSA 3.1
Started IMRT 9/22/2015

Nope - it's not significant at all and serves no purpose other than to scare you. It shouldn't have been done, imho. Exploding prostate cells (cancerous or not) churn out PSA, so it may take years to learn anything definitive.