Background
Phase II single-arm trial (SWOG S0809). 79 patients with extrahepatic cholangiocarcinoma (eCCA) or gallbladder cancer (GBC) who underwent curative-intent resection (R0 or R1). Designed to test adjuvant gemcitabine + capecitabine (gem/cap) chemotherapy followed by concurrent capecitabine-based chemoradiation (CRT). Primary objective: establish a favorable 2-year OS benchmark ≥45% (null hypothesis 45%, alternative 65%).
Interventions and follow up
Arm A: Gem/cap × 4 cycles (gemcitabine 1000 mg/m² d1,8 + capecitabine 650 mg/m² BID d1–14, q3wks) → concurrent RT 45 Gy ± boost to 54 Gy + capecitabine 1500 mg/m² BID
Arm B: N/A — single-arm phase II
Primary endpoint: 2-year overall survival
mFollow up: 35 month
Arm B: N/A — single-arm phase II
Primary endpoint: 2-year overall survival
mFollow up: 35 month
Results
2-year OS: 65% (exceeded 45% target, P=.006)
Median OS: 35 months
2-year OS (R0): 67%; 2-year OS (R1): 60%
Grade 3/4 toxicity: 52% (grade 3), 11% (grade 4)
Median OS: 35 months
2-year OS (R0): 67%; 2-year OS (R1): 60%
Grade 3/4 toxicity: 52% (grade 3), 11% (grade 4)
Adverse events
Main adverse events: Grade 3+ toxicity 63% (mostly hematologic and GI). Grade 4 toxicity 11%. Two treatment-related deaths. Toxicity was substantial but manageable. R0 vs R1 resection margin status had limited impact on OS — unusual finding highlighting potential utility of CRT for R1 disease.
Conclusions
Adjuvant gem/cap followed by CRT achieved 65% 2-year OS (median 35 months) in resected eCCA/GBC, exceeding the predefined threshold, with R0 and R1 patients achieving similar outcomes — suggesting that CRT may overcome the impact of microscopic margin involvement in biliary cancers.
Key Limitations
Key Limitations: Single-arm phase II — no comparator arm; historical control comparison only. Substantial toxicity (63% grade 3+, 2 treatment-related deaths). Mix of eCCA and GBC histologies which may have different biology and radiation sensitivity. The high toxicity rate limits broad applicability outside experienced centers. BILCAP (capecitabine alone, no CRT) subsequently showed simpler adjuvant chemotherapy also improves OS — the incremental benefit of CRT over chemotherapy alone is not established.
Clinical Context
SWOG S0809 is the primary prospective evidence supporting adjuvant CRT (after chemotherapy) for resected eCCA and gallbladder cancer. The similar outcomes in R0 and R1 patients support the use of CRT to sterilize microscopic residual disease. In the US, adjuvant CRT after resection of eCCA/GBC is a standard option per NCCN for R1 or LN-positive disease. The optimal adjuvant strategy — chemotherapy alone (BILCAP) vs CRT (SWOG S0809) vs sequential (as tested here) — remains an open question without a direct randomized comparison.
References