First, welcome to the board!
I'm glad you have already had some informative posts from some of the survivors with advanced prostate cancer, and I'm in that group too. The trio of books recommended by Tom ("Gleason9") and GUAMJOHN are superb - great for all of us patients, but especially for patients with advanced disease. These doctors really know what they are talking about based on long experience with hormonal therapy, chemotherapy, and other options for advanced patients.
Unfortunately, many doctors treating prostate cancer patients are not that well informed or experienced when it comes to treating patients with advanced cancer.
Here's a key point: survival of high risk prostate cancer patients in the US is 95% at the ten year mark, provided they get good treatment. Except for a very, very few patients, prostate cancer does not kill quickly, unlike all other major cancers.
I'm glad to learn your dad is already on hormonal therapy. One typical way of delivering the key family of drugs, known as LHRH-agonists, is by a shot, every 1, 3 or 4 months, and I suspect that's what your dad is getting. It's clear that it has had the expected minimum impact, driving his PSA down from 12 to the range of 0.6 to 1.7.
However, one drug is typically not enough to do the job. The LHRH-agonists (such as Lupron or Zoladex, etc.) are designed to minimize the production of testosterone from the testes, and, if well delivered in the overwhelming majority of patients, they do that well. However, for about 10% of patients, there are drug delivery problems, oddities in the patient's individual biology such as shorter than normal time to clear the drug, or both. Therefore, the experts consider it vital
that the patient be tested for both testosterone level and DHT, which is made from testosterone and is far more potent as a fuel for the cancer. It's probably okay to omit these tests if the PSA has dropped to the low hundredths, such as 0.05 or lower, but your dad's is not that low.
Also, even when patient's have experienced the desired plunge in testosterone, the adrenal glands, after being alerted to the body's shortage of testosterone, can ramp up their indirect production of testosterone. Often this is only about 5%, a concern, but not a major issue. However, in some men the adrenals can jack up the supply to around 40% of normal. Moreover, whatever testosterone is present can still be converted to far more potent DHT (dihydrotestosterone).
Therefore, the experts strongly advise using more than just one drug for most patients with challenging cases (metastatic qualifies as challenging). The drugs known as "antiandrogens" - Casodex (now generically bicalutamide) or flutamide (much less desirable - less effective and harder to manage) are the "first line" antiandrogen options for blocking the docking sites on the cancer cells so that the cancer fuel (mainly testosterone and DHT) cannot be delivered. The drug finasteride or the drug Avodart (dutasteride) go a long way toward eliminating the conversion of testosterone to DHT, and they also help in other ways, such as reducing the needed supply of blood to the cancer. This is a short course in hormonal blockade; the books provide a clear and detailed explanation.
In short, just one drug is probably not at all enough for your dad.
Regarding the side effects that you mentioned, the doctor should have gone over countermeasures to minimize them. However, many doctors are ignorant about countermeasures, and quite a number are even ignorant about the side effects. The books do an excellent job about them, especially "Invasion."
I would like to highlight just one side effect now: hormonal therapy often leads to a decrease in bone density. It's very important to get bone density measured with a bone mineral density scan. Most of us need a drug from the drug class known as "bisphosphonate." Often a milder drug from the class will do, such as Fosamax (generic alendronate now available), or Actonel, but for metastatic patients, Zometa is often the drug of choice. It's very powerful.
This is getting long so I'll mention just two more points. Lifestyle tactics - well described in the books - appear to be very important to success for us more advanced patients. They involve diet/nutrition/supplements, exercise and stress reduction.
The other point is that some patients with just a few metastatic hot spots do very well on hormonal therapy after those spots are targeted with radiation. This field of research goes by the awkward name "oligometastatic" prostate cancer.
Take care and good luck,