The same disease meaning the same cancer, or just some type of cancer? You can still think logically about it. If the same cancer, how old were they when symptoms appeared? At what age are most people who suffer from that condition? What was their initial prognosis? Is this condition known to be genetically related or caused? Has a doctor ever said you were at higher risk for it? Are you in a risk category otherwise?

This is obviously important to you and it comes up often in your posts; I'm just suggesting you try to train yourself to think about it more scientifically.