Activities in Gastrointestinal Endoscopy Study Group of Japan Clinical Oncology Group (JCOG-GIESG)

The Japan Clinical Oncology Group (JCOG) is a multicenter clinical study group for cancer treatment mainly funded by the national research grants in Japan. JCOG has 16 subgroups by specific tumor types or modalities.
Gastrointestinal Endoscopy Study Group was established in 2011, and now 47 institutions nationwide in Japan are participating. We have conducted eight clinical trials. JCOG0508 showed the comparable efficacy of the combination of diagnostic endoscopic resection followed by selective chemoradiotherapy (CRT) to the surgery (Gastroenterology 2019). Based on JCOG0508 results, this minimally invasive treatment strategy is now recognized as one of the standards of care for the patients with T1b (SM1-2) N0M0 thoracic esophageal squamous cell carcinoma (ESCC). JCOG0607 and JCOG1009/1010 showed good 5-year overall survival in the patients after ESD for the expanded indication of differentiated-type (JCOG0607) and undifferentiated-type (JCOG1009/1010) early gastric cancer (EGC) (Gastric cancer 2018, Gastric cancer 2021). According to the results of these studies, clinical treatment guidelines for ESD in Japan expanded the indication. JCOG1604 (single-arm confirmatory trial for the usefulness of EUS for diagnosing cancer invasion depth of clinical stage IA ESCC) could not show the superiority of EUS to image enhanced endoscopic diagnosis.