If he hasn't had any long period of hormone treatment before, then the prostate cancer is usually powered by testosterone. The hormone treatment will prevent the body producing testosterone, and that will stop the cancer growing, and it can even shrink. This should also reduce any pain from bone mets. PSA is likely to fall to single figures and can even drop lower than 1 (although possibly not with a starting point of 1000).
This treatment can last many years, but eventually the cancer mutates and learns to grow even without testosterone (referred to as castrate resistant, although the hormone therapy is being used instead of castration nowadays). When the hormone treatment starts failing other drugs are added to try and slow the cancer growth, e.g. bicalutamide (150mg, a higher dose than you're on now) typically adds something like 6 months to the effectiveness.
The loss of testosterone has side effects, most specifically to sexual function. However, there are others too such as loss of body hair obtained a puberty (and conversely, prevention and sometimes reversal of balding, loss of body odor). He may also get many symptoms of menopause, such as hot flushes, and osteoporosis. The latter when added to bone mets significantly increases risk of bone fractures, and additional medication may be given to try and counteract that.
The bone biopsies - my guess is they want to be sure this is just prostate cancer and not some other type of cancer. Prostate cancer is relatively easy to slow down in the initial stages with hormone therapy as above, but many other cancers aren't, and if they find some other types of cancer, additional treatments may be required or they could be looking at different medium term prognosis.
Edited by member 10 Apr 2019 at 11:26
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