The role of adjuvant radiotherapy in microscopic tumor control after extrahepatic bile duct cancer surgery

Objectives: To evaluate effects of radiotherapy (RT) after surgery for extrahepatic bile duct (EHBD) cancer. Methods: There were 60 patients with EHBD cancer treated with postoperative RT. Surgical extents were R0 in 24 patients, R1 in 23, and R2 in 13. The indications for adjuvant RT were positive resection margin, lymph node metastasis, or more than pT2. Radiation was delivered to tumor bed and regional lymphatics, and for R1 or R2 patients, boost RT was planned. Overall survival (OS) and progression-free survival (PFS) was calculated and survival in the R0 and R1 patients with negative lymph nodes was compared. The pattern of treatment failures and prognostic factors were analyzed. Results: The 2- and 5-year survival rates were 36.6% and 12.3% for OS, and 31.2% and 16.2% for PFS. In comparison of R0 with R1 patients who had negative lymph node, 2-year OS and PFS were 53.0% and 55.0% in R0, and 40.7% and 36.7% in R1 (P = ns). The first site of failure was loco-regional in 29 patients. The lymph node metastasis was a significant prognostic factor in OS (P = 0.04) and PFS (P = 0.02). Conclusions: Lymph node metastasis was a poor prognostic factor and adjuvant RT may be useful in patients with microscopic residual tumor. However, because there were high loco-regional recurrences, additional study is needed to determine more effective RT such as increased RT dose or use of radiosensitizers.