Jemison5

I am trying to find out what my father has. He went to the hospital after becoming very jaundice about 2 weeks ago. The doctor's determined he had clogged bile ducts,and did a temporary surgery to put in stints. They found a mass in his duct and did a biopsy.They are telling us he has a cancer called klatskin's cancer. The first biopsy came back negative for cancer and they said they wanted to do another biopsy. They had to do another surgery to put in longer stints and do a second biopsy. We have not been told the results of the second biopsy yet, but the doctor seems convinced we are dealing with Klatskin's bile cancer. I am so confused??? How do they assume that is what this is? How do we find out for sure, and where is the best place to be to handle this? If anyone can help me understand this better, I would love to hear from you. We are being told he has five months or five years to live. He is 65 and has been a drinker for many years. There is no cancer in our family. Is this hereditary? Thanks, Jemison5