Radiation therapy for extrahepatic bile duct cancer: Current evidences and future perspectives

Abstract

Extrahepatic bile duct cancer (EBDC) is a rare malignancy that involves neoplastic changes extending from both hepatic ducts to the common bile duct. The treatment of choice is surgical resection, but the predominant pattern of initial treatment failure is locoregional recurrence. Accordingly, adjuvant radiotherapy has been administered after surgical resection based on these rationales. At this time, there is minimal evidence supporting adjuvant radiotherapy, because there have been no phase III trials evaluating its benefit. Relatively small retrospective studies have tried to compare outcomes associated with EBDC treated with or without radiotherapy. We aimed to review studies investigating adjuvant radiotherapy for resected EBDC. Because less than one-third of EBDC cases are amenable to curative resection at diagnosis, other locoregional treatment modalities need to be considered, including radiotherapy. The next aim of this review was to summarize reports of definitive radiotherapy for unresectable EBDC. Patients with advanced EBDC often experience biliary obstruction, which can lead to jaundice and progress to death. Biliary stent insertion is an important palliative procedure, but stents are prone to occlusion after subsequent ingrowth of the EBDC. Radiotherapy can be effective for maintaining the patency of inserted stents. We also reviewed the benefit of palliative radiotherapy combined with the biliary stent insertion. Lastly, we discuss the existing gaps in the evidence supporting radiotherapy in the management of EBDC.

Clinical Outcomes and Risk Stratification in Unresectable Biliary Tract Cancers Undergoing Radiation Therapy

“…Our treatment approach primarily involved a hypofractionated RT regimen concurrently with 5FU-based chemotherapy. This treatment modality aligns with current standards for unresectable BTC (32)(33)(34)(35). Approximately half of the patients received chemotherapy before or after RT, indicating variability in treatment sequences.…”

Variation in clinical target volume delineation in postoperative radiotherapy for biliary tract cancer

“…A total of 27 CTVs for dEBDC, pEBDC, and GBC delineated by nine clinicians were analyzed (Table 2). The mean and standard deviation of CTVs were 120.62 ± 40.98 cm 3 for dEBDC, 152.05 ± 54.84 cm 3 for pEBDC, and 131.94 ± 46.93 cm 3 for GBC. The degree of agreement was moderate in all cases; overall kappa values were 0.573 for dEBDC, 0.513 for pEBDC, and 0.511 for GBC.…”

“…Significant differences in survival are found according to the resection status. The 5-year survival rates are up to 50% with a complete resection, but decrease to as low as 0% with an incomplete resection or without resection [3][4][5][6][7]. To improve prognosis of advanced BTC, immunotherapeutic agents can be added to the first-line treatment [8].…”

Proton Beam Therapy for Unresectable Perihilar Cholangiocarcinoma

“…Concurrent chemotherapy did not improve survival in our study. Chemoradiotherapy was reported to be associated with better survival than radiotherapy alone [34]. Further large-scale prospective studies are necessary to determine the effectiveness of concurrent chemotherapy with PBT.…”