First of all ,I am not a doctor,I am just a patient.
I presume the surgeons that told you your father CCA was unresectable after they opening him up are GI surgeons; did the surgeon told you the REASON why the tumor cannot be resected at that time. Are they LIVER surgeon and not just general GI surgeons. If not ,seek a 2nd opinion by a liver surgeon is my suggestion especially your message above stated that "liver:shows evidence of pneumobilia(free air,may be due to the procedure of insertion of the stents) and stent seen in site..No definite FOCAL lesion seen in liver parenchyma...
No obvious extraneous mass lesion seen in the region of porta hepatis ... unless what it means is EXCEPT the original tumor,the new finding on this scan is irrelevant or unrelated to the subject being dealt with(ie: the original findings of the tumor.) and if otherwise, this is a very good news.
btw, THE SCAN NEVER REPORTED ANYTHING ABOUT THE COMMON BILE DUCT AND ANYTHING INVOLVED THE LEFT AND RIGHT HEPATIC DUCTS, PORTAL VEIN AND HEPATIC ARTERY JUST BELOW THE PORTA HEPATIS.
I know you may intent to just put out the most important part of the scan and may not the completed (full) report as you use the .... at the end of some sentences and i understand;but if your father did not have any other health related problems, then the following suggestion and the above ones may be of help to you.
"Previous CT Scan shows tumour at the level of porta....! But now the report said:"No obvious extraneous mass lesion seen in the region of porta hepatis ..."
What is your opinion in this regard???" .
This is rather surprising to me too. I guess the GEM/CIS works and shrinks the tumor completely (complete response?)or the stent works .(some stents are coating with chemotherapy agent to block further growth of the tumor at site of insertion. You need to bring this finding up and ask the oncologist why he/she want to stop the GEM/CIS chemotherapy since according to the recent scan, the tumor is no longer there and it seems the chemotherpy is working, ask for the specific reason not to continue the GEM/CIS.
How about getting another MRCP to confirm the CT scan findings for further treatment plans.
I am not in India, and not familiar how the medical systems work. But I know ,if financial matters is no concern, There are excellent private hospitals as well as specialty surgeon and doctors in most of the Asia countries that can provide the same if not better care for their patient than the States here.
Please know that my personal opinion is not intended nor implied to be a substitute for professional medical advice. If provided, information are for educational purposes.Consult doctor is a MUST for changing of treatment plans.