What do you suggest if my grand father had adenocarcinoma and i want to know what causes it or what contributes to you getting it?

Depends: "Adenocarcinoma" is a general term for a cancer that begins in the glandular elements of an organ. Thus, adenocarcinoma can refer to cancer of breast, lung, pancreas, stomach, bowel, etc. Your risk would depend on where that cancer was, what age it occurred, and who else in family had cancer. If grandfather was only cancer case, and if it was at an advanced age (over 50), hereditary not likely.