No I know this not from google but from someone that I knew who died from it and as far as using the word "track" this is the word that the Dr used to keep an eye on the progress of the disease so I am not sure why you find that so unusual.
As i've stated in previous posts, there isn't 1 specific PERFECT tumor marker that we follow for someone with cholangio...
We look at CEA, CA 19/9, Biliary Insulin-like growth factor (sometimes)... its important to have pre-op/pre-treatment values to compare to post-treatment values for follow up. This Doc may have followed the only tumor marker that was drawn pre-treatment... this DOESNT mean that everyone follows this specific marker for that type of cancer. do you understand?
Did your friend have Ulcerative Colitis or Primary Scherolsing Cholangitis prior to his diagnosis of cholangio ca... and was the cancer Adeno (glandular, most common- about 80% of cholangio ca) or squamous cell varient? (far less common)
For a lot of other cancers tumor markers mean much more... Breast Cancer and the BRCA1 and 2 mutations have been researched a shit load and are now used in genetic counseling of family members... other cancers we are still WAY behind... for example- pancreatic cancer research is my area of interest. That is def one son of a bitch that you don't want to get... My old med school anatomy professor told me if you get pancreatic CA "Get yourself a bottle of champagne, a blonde whore and kiss your ass good bye" LOL Sadly, times haven't changed much.