He is at the advanced stage. he didn't feel any pain when the cancer was invading up his liver. how can that be possible?

Silent killer: Cancer is a silent killer & it crept up on him slowly. People tend to ignore these 7 symptoms. C- change in bowel or bladder habit a- a sore that doesn't heal on skin or on mouth u- unusual bleeding or discharge from rectum, bladder, or vagina t- thickening or lump in the breast tissue i- indigestion or difficulty swallowing o- obvious changes in a wart or mole n- nagging cough or hoarseness.