My tumor maker: ca 19-9 is 105. Does this mean its cancer?

Not necessarily. Ca 19-9 is not to be used to screen for any cancer as it is nonspecific test. Why is it done on you? Any symptoms or any abnormal signs? It can be elevated in different condition such as in pancreatitis, hepatitis, biliary obstruction, or other biliary disease. It may also be elevated in various GI cancer such as colon, liver, pancreas, biliary etc. Follow up with your md for further evaluation.