i am not going to reccomend any therapies in this post. i only want to say that NO! it is definitely not too late. healing is always possible, and if you father truly has a desire to live then he will find a way. some people develop cancer becaue their time on earth is over, some because they choose for their time to be over, some due to bad decisions earlier in life. aks him if he wants to live and would be willing to try an alternative therapy. if the answer to both is yes, then get on with choosing a protocol and making it happen. people have recovered from cancer further along than your father, it can happen. also pray and have some faith, The Creator responds to faith.
its been my experience that no matter the outcome making a concerted effort toward health and wholeness alwlays pays off in high dividends, physcially AND emotionallly.