I was tested for PSA every three weeks while going through a clinical trial at NIH. The initial drop when placed on HT was dramatic, although not as steep as that of your husband- and the rate slowed down as I got closer to nadir
with regard to the HT wearing off, I expect that the zoladex circulating in the blood decreases over time from the last shot, BUT the dosage is calculated to maintain the serum concentration above that which will saturate the binding at receptors in the pituitary gland in the brain- so you should be comfortable the zoladex effect is not wearing off in the three month timeframe-
also know that both the HT and the chemo are attacking the PCa cells, reducing the PSA accordingly. I had to stop chemo after only four cycles, and my next PSA showed the least rate of decrease, and then a small bump after that one (again at 3 week intervals); that is only a correlation, however. In early January I get my first three-month check on PSA, we shall see if I did hit true nadir at 5 months in early October.
there are studies that indicate a longer, slower approach to nadir (out to 6+ months in time) correlates with improved outcomes, so slowing down in the approach to nadir is not necessarily a signal of decreased effectiveness in therapies, it could be a good sign overall.
your husband has shown a remarkable response to primary therapy given his high start point- like me and my wife, you guys are "in the zone" for now (when primary therapy is working great)- enjoy it!
I say that like it is so easy to do... I know the effort it takes to do that; I have found that having things to look forward to in the near future helps me to be focused on other than PCa, and towards that end wife and I are heading to hot springs in SW Colorado (done that before) and snowmobiling (bucket list thingie) for the New Year's Eve weekend- maybe we can even stay awake long enough to ring in the new year at a pub 2 blocks from our hotel- like when we were young....
I still wake up each morning with "yup, I still got it" but it gets easier to cope with each day because we are "in the zone" for now.
as are you guys.
have fun, especially once the chemo cycles are done-
here's to fightin'
Dx @ 62yo
2012-15: PSA 6-14, 2x neg Bx
3/16 PSA 19.4
Bx G10/8 bulky mets P+RP LN
5/9 ADT PSA 29.5
NIH trial: PROSTVAC + ADT + chemo (4 rnds)
PSA nadir .05 on 10/4
10/25: PSA .06 Scans- no bone mets, nodes shrunkwww.healingwell.com/community/default.aspx?f=35&m=3634829