Yes, this is a good reason to question what tests have been made to the point and what the doctor or doctors have said. Cancer is not easily missed, especially at the stage this person is describing.
I am sorry to hear of your situation and do take the time to read more on Jesicha's Hope, there are treatments that are demonstrating very good outcomes. Chemo works for a time but as the cancer progresses, it weakens the body so that it cannot recover.
I wish you well.