Just to update my contribution to this thread, yesterday my clinical oncologist handed me back to my medical oncologist for the next phase of my treatment. As my PSA has continued to increase (it currently stands at 6.97, up from 3.83 in two months), my Zoladex is to continue indefinitely, and I will be staring Apalutemide next month. I have just started on Medroxyprogesterone to try and get the worst of the Zoladex side effects under control before starting the Apalutemide.
The consensus is that we are no longer trying to cure my PC, but to prolong my life. Not the best news I have ever received, but after talking at length to my oncologist, I remain relatively upbeat as any prolongation may extend to a decade or more. I am currently 77 and symptom free.
On the plus side, following extensive tests there is no trace of distant mets and my PC remains advanced but localised. The pain in my legs continues to baffle, with an ultrasound scan and an appointment with a podiatrist in the pipeline.