The role of postoperative radiation therapy (PORT) in the treatment of extrahepatic bile duct cancer: a surveillance, epidemiology, and end results (SEER) population-based investigation.

PURPOSE: Extrahepatic bile duct cancers (EBDC) are aggressive cancers for which the importance of the use of postoperative radiation therapy (PORT) in potentially curative cases remains the subject of clinical investigation.
METHODS: The 1973-2004 National Cancer Institute Surveillance Epidemiology and End Results (SEER) database was analyzed for patients with EBDC who had undergone cancer-directed surgery. Patients who died <3 months after surgery were excluded from analysis. Patients with distant metastases, with unknown stage or interventions, or benign histologies were excluded.
RESULTS: Nine hundred fifty-six patients were selected. Tumor-related factors, such as regional (vs. local) disease and an increasing number of lymph nodes predicted for the delivery of PORT. In unadjusted univariate analysis, patients treated from 1973 to 2004 who fit the selection criteria had a lower 3-year survival rate if they received PORT vs. no PORT (3 year survival 31.3% vs. 39.6%, p = 0.04), but this improvement did not hold in multivariate survival analysis or in univariate analysis of patient subsets.
CONCLUSIONS: Based on analysis of the SEER database, there was no definitive evidence for improved survival with the addition of PORT to radical surgery. This analysis should be approached with caution given its observational and retrospective nature. In addition, it should be remembered that the SEER database lacks information on the use of chemotherapy, radiation technique, and the completeness of resection.