Telling your father he has Cancer

As a medical student I've always wondered how I would handle the situation when I first have to tell a person and their family they have a life threatening disease like cancer.
Today, just five minutes ago, I told my father he has cancer. Last night I feared tears would flow from my eyes and I wouldn't get the words out, knowing the probably prognosis, I felt it would be impossible to get the words out and stay positive.
No tears came, I said the words, "you likely have cancer" (I coped out and didn't make it a definitive as it surely is) like I was telling him "you have an ulcer." Now I want to cry, I imagine whats transpiring in his mind as I write these words. The first realization that something, Cancer, is inside him, and what will now happen in his life...is he scared, of course, is he resilient, does he think he'll beat it, does he think of his family and how they'll cope, if I know my father this is probably the closest to the truth...
What should I do, whats my role now... as close as I am with my dad, sharing emotions has never been our strong suit, his most controversial talk with me was when I was 16 and he sat me down and told me "sex is like water, you need to survive," probably anticipating my sexual maturation and wanting to let me know that my thoughts were natural.
What worries me most, is that my father recently saw his closest friend succumb to pancreatic cancer. The worst of all cancers, still thinking about the ordeal makes me cringe with horror... the pain, the slow degeneration, his friend my uncle "a poet at heart" dealt with the disease in the most courageous and beautiful way... naive to what was to come along each step he amazed us with his resilience. My dad doesn't have the benefit of being naive to whats coming. He's seen it, recently, he was there for his friend, for their family, he looked after his children like his own, and demanded that my mother, my brother, and I to do likewise. Does he have someone to trust with his own family? does he trust that my brother and I are old enough and mature enough to take care of my mom...
Does he cry..does he.. do I want to know...
My dad has always had all the answers, he's never been frieghtened of anything, he's never shown weakness... am I ready to see it, do I need to force it out of him... what should I do
I can't write anymore.