Hi.
There is no accurate means of saying how long anyone has, but of course, there is the experience of other patients.
While the presence of bone metastasis is not reassuring, it is not a herald of death within a few months.
Much of survival will depend on what stage of the disease he is in, is he still receiving any hormones? If he is then this is a good thing. Patients who are non-responsive to hormones would have a shorter median survival (this means about half of patients reach this mark, the other half does better) of the order of 14 to 18 months
Another important aspect is how strong your grandfather is- whether he is able to carry out his daily activities with little or no assistance. Other issues are the presence of other diseases like diabetes, hypertension, kidney and heart disease. If he is perenially bedridden, the estimate of a year and a half may be shorter- whether this is only because of the cancer or his age/other problems.
My father was just re-diagnosed and is asking himself the same question (Pgh, PA). I was just wondering how your father is doing? Is his PSA level very high? I read that is typically is a good indicator of the amount of cancer cells in one's body. Also, if it doubles within 6 months that is not a good sign. Have the doctors discussed anything that might help slow it down from spreading - like supplements to try or anything? Thats what I'm trying to look into - although, I know there is no miracle pill, I'd rather try something - anything!
None of us one can estimate the time we have left with our loved ones, but I pray he is with you long enough for you to tell him everything you ever wanted to, and without much suffering. My thoughts and prayers are with you and your father.