The following article features coverage from the ASCO Gastrointestinal Cancers Symposium 2022. Click here to read more of Cancer Therapy Advisor’s conference coverage.

Adjuvant therapy with S-1 improved overall survival (OS), compared with surgery alone, in patients with curatively resected biliary tract cancer (BTC), according to phase 3 results presented at the ASCO Gastrointestinal Cancers Symposium 2022.

Although adjuvant capecitabine has been recognized as the standard of care for curatively resected BTC, it does not improve OS compared with surgery alone, noted Masafumi Ikeda, MD, PhD, of National Cancer Center Hospital East in Kashiwa, Japan, who presented the phase 3 results at the meeting.

Dr Ikeda pointed out that S-1, an oral fluoropyrimidine derivative, “has been established to be a standard therapy for patients with resected pancreatic cancer and gastric cancer in Japan.”

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With that in mind, Dr Ikeda and colleagues conducted the phase 3 JCOG1202: ASCOT trial to determine if adjuvant S-1 could improve outcomes for patients with BTC undergoing resection with curative intent.

The trial included 440 patients with BTC who had undergone an R0/R1 resection. They were randomly assigned to receive either no further anticancer treatment (n=222) or adjuvant S-1 for 4 cycles (n=218).

Baseline characteristics were similar between the treatments arms. The median age was 68 years in the S-1 arm and 70 years in the surgery-alone arm (overall range, 33-80 years).

For most patients, the primary tumor site was extrahepatic (57% in the S-1 arm and 55% in the control arm). Most patients had stage 2 disease (58% and 59%, respectively), and a majority had an R0 resection (86% and 85%, respectively).

The researchers found that S-1 significantly prolonged OS. The 3-year OS rate was 77.1% with S-1 and 67.6% in the surgery-alone arm (hazard ratio [HR], 0.694; 95% CI, 0.514-0.935; P =.008).

The 3-year relapse-free survival (RFS) rate was 62.4% with S-1 and 50.9% with surgery alone (HR, 0.797; 95% CI, 0.613-1.035).

Dr Ikeda noted that the difference in RFS was not significant at the 3-year mark, but S-1 was associated with improved RFS at prior time points. Therefore, he said, longer follow-up is needed.

S-1 was considered well-tolerated. Common adverse events (AEs) included immunosuppression, gastrointestinal toxicity, and skin toxicity. The most common grade 3-4 AE was neutropenia, affecting 15% of patients.  

Based on these results, Dr Ikeda concluded that “adjuvant S-1 therapy is considered to be the standard of care for resected biliary tract cancer.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Read more of Cancer Therapy Advisor’s coverage of ASCO GI 2022 by visiting the conference page.


Ikeda M, Nakachi K, Konishi M, et al. Adjuvant S-1 versus observation in curatively resected biliary tract cancer: A phase III trial (JCOG1202: ASCOT). Presented at ASCO GI 2022; January 20-22, 2022. Abstract 382.