1. Yes, I have often performed in-between PSA-measurements. I don't think there is much of a trouble with the PSA-bounce, since you see the bounce usually after treatment and not during it.
I usually perform a PSA-measurement immediately at the beginning of RT and then 5 weeks later. It's not helpful in all patients and in some, the test results will rather confuse you. There are patients who may benefit from this approach, because you will spare them from aggressive treatment.
I've had a patient starting RT with a PSA of 0.4 ng/ml and who at week 5 had a PSA of 0.7 ng/ml. He was tolerating treatment bad, so we decided to stop at week 5. Follow up showed further progression and he was metastatic, as suspected.
I normally do this in-between testing only in patients I know of having a high PSA-velocity. If the PSA was rising at a rate of 0.1-0.2 ng/ml over 3 monthly intervalls before RT, then the test won't help you guide treatment. Patients with a doubling time which is considerably less than 6 months are better candidates for the approach.
Wiegel has studied this:
http://www.ncbi.nlm.nih.gov/pubmed/12240547
He has shown that patients who don't fall off with their PSA by week 6 can almost never be cured with RT.
2. I do not give concurrent ADT for node-negative patients. RTOG 9601 has now reported long-term results with a potential survival benefit of 4% with the concurrent use of 24 months of bicalutamid with RT (after 10 years!), but:
a) this is a 90s trial, meaning that patients recurring after salvage-RT had very little chance of getting any other treatment. Docetaxel was the option in the 2000s, no enzalutamide, no abiraterone. It's thus questionable, if the OS-survival would still happen, if the trial was run again today, especially if we speculate that ADT is not curing patients but rather "pushing" progression "down the road".
b) the patients in the trial, that benefited were mainly those with high PSA-values (>0.7 ng/ml, especially >1.5ng/ml). Patients with PSA-values <0.7ng/ml didn't seem to benefit. Nowadays you shouldn't be getting salvage RT patients referred to you with PSA-values that high and should ideally treat them at PSA-levels <0.5 ng/ml.
c) staging before RT in the trial was done with a CT-pelvis. I presume that since lots of patients in the trial had high PSA-levels, that some of these patients actually had macroscopic recurrences at the time of RT. Nowadays modern MRI would have picked up these patients and you would have good reasons to perform dose escalation or give hormones to RT in those selected cases.
For these reasons I am not convinced, that giving ADT should become standard of care for all patients with salvage RT. One could consider it however for patients with high psa-levels. I would give it for pN1-patients as well.
3. I would be cautious about Docetaxel in non-metastatic patients.
The Stampede data are good, but more than half of the patients randomized has systemic metastasis. We do not know if the locally-advanced & pelvic-node-positive patients will benefit that much from Docetaxel as well. Looking at the CHARTEED data, we know that mostly "high-volume" systemic metastatic patients benefit from Docetaxel, not the "low-volume" disease patients. A patient with a locally advanced N0 M0 tumor is not a patients with "high-volume" disease. The GETUG-12 trial
(
http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(15)00011-X/abstract ) for locally advanced disease did not show an OS-benefit, but only a PFS-benefit. I would await long-term results from this trial, as well as subgroup analysis from the Stampede trial and results from the currently recruiting RTOG-trial before going for Docetaxel in the non-metastatic patients together with RT.
