Failure patterns after curative resection for intrahepatic cholangiocarcinoma: possible implications for postoperative radiotherapy

Background To explore the patterns of failures and areas at highest risk of recurrence for postoperative intrahepatic cholangiocarcinoma (IHCC), with the aim to guide IHCC adjuvant radiotherapy. Methods Patients with IHCC who had undergone radical surgery at our institution from July 2010 to August 2017 were retrospectively analyzed. The survival and prognostic factors were analyzed by univariate and multivariate analysis. All sites of recurrence were found out and classified as the surgical margin, regional lymph nodes, liver remnant and distant metastasis. According to the recurring area at highest risk, the target volume of adjuvant radiotherapy was proposed. Results The median follow-up time was 23.5 months (2-85 months). The median recurrence free survival (RFS) and overall survival (OS) were 12.1 months and 24.8 months, respectively. Seventy-three (73/127, 57.5%) IHCC patients developed tumor recurrence. Initial recurrences occurred in the potential postoperative radiotherapy (PORT) volume, remnant liver and distant sits were 46 (46/73, 63.0%), 36 (36/73, 49.3%) and 22 (22/73, 30.1%) cases, respectively. Of the 46 patients whose initial recurrence inside the potential PORT volume, 29 (29/73, 39.7%) developed recurrence only inside the potential PORT volume, including 13 tumor bed recurrences, 7 lymph node metastases, and 9 with both tumor bed recurrences and lymph node metastases. The most common lymph node metastases sites were nodes around the abdominal aorta, followed by lymph nodes along the celiac artery, the common hepatic artery, and in the hepatoduodenal ligament. Conclusions High proportion of the recurrences occurred only inside the potential PORT volume, implying adjuvant radiotherapy might improve the local-regional control. Surgical margins and lymph node stations No.16a2, 9, 8, 12, 13, and 14 are suggested to be included in the radiation volume.