Second-line Regimen Combined With Radiotherapy Versus Without Radiotherapy in Patients With Locally Advanced/Oligometastatic ICC After Failure of First-line Treatment：an Open-label, Randomized, Controlled Phase II Clinical Study

Inclusion Criteria: * (1) Advanced or metastatic intrahepatic cholangiocarcinoma confirmed by histopathology that cannot be surgically removed. (2) Failed to receive first-line standard treatment. (3) Definition of oligometastatic/locally advanced unresectable BTC disease: not a candidate for surgical resection at all sites: surgery to all sites not recommended by multidisciplinary team, or unfit or declining surgery. (4) Definition of oligometastatic disease: patients with distant organ metastasis or nonregional lymph node metastasis, or distant organ/nonregional lymph node metastasis and regional lymph node metastasis, as defined by the American Joint Committee on Cancer, 8th edition. The total number of metastases is ≤5 and the number of metastases in any single organ system (e.g., lung, liver) is ≤3. (4) All sites of disease must be amenable to radiotherapy and can be safely treated. Each lesion is counted separately at the time of registration and contributes to the total number of metastases. For regional lymph nodes metastases, all positive regional lymph nodes are counted together as one lesion. For nonregional lymph node metastases, adjacent metastatic lymph nodes can be treated as one lesion. Lesions that have subsided during previous treatment (i.e., are no longer visible on CT scan or have eliminated affinity on positron emission tomography \[PET\]-CT) are not included in the total number. At least one metastatic lesion meets the RECIST v1.1 criteria for…