ESTRO 2024 - Abstract Book

S1221

Clinical - Head & neck

ESTRO 2024

691

Poster Discussion

A single-arm confirmatory trial of IMRT alone for early-stage oropharyngeal cancer: JCOG1208

Satoaki Nakamura 1 , Takeshi Kodaira 2 , Ryunosuke Machida 3 , Takeo Nakashima 4 , Yoshinori Ito 5 , Naoki Nakamura 6 , Satoshi Ishikura 7 , Takashi Toshiyasu 8 , Yoshihiro Saito 9 , Satoru Takahashi 10 , Yosuke Ota 11 , Masahiro Inada 12 , Yuji Murakami 13 , Nobuteru Kubo 14 , Yuta Sekino 3 , Haruhiko Fukuda 3 , Yasumasa Nishimura 15 , Takashi Mizowaki 16 1 Kansai Medical University, Radiology, Hirakata, Japan. 2 Aichi Cancer Center, Radiation Oncology, Nagoya, Japan. 3 National Cancer Center Hospital, JCOG Data Center/Operation office, Tokyo, Japan. 4 Hiroshima University Hospital, Clinical Practice and Support, Hiroshima, Japan. 5 Showa University School of Medicine, Radiation Oncology, Tokyo, Japan. 6 St. Marianna University School of Medicine, Radiation Oncology, Kawasaki, Japan. 7 Tokyo Bay Makuhari Clinic for Advanced Imaging, Cancer Screening, and High-Precision Radiotherapy, Radiation Oncology, Chiba, Japan. 8 Cancer Institute Hospital of JFCR, Radiation Oncology, Tokyo, Japan. 9 Saitama Cancer Center, Radiation Oncology, Saitama, Japan. 10 Jichi Medical University, Radiation Oncology, Shimotsuke, Japan. 11 Hyogo Cancer Center, Radiation Oncology, Akashi, Japan. 12 Kindai University, Radiation Oncology, Osaka-Sayama, Japan. 13 Hiroshima University, Radiation Oncology, Hiroshima, Japan. 14 Gunma University Graduate School of Medicine, Radiation Oncology, Maebashi, Japan. 15 Fuchu Hospital, Radiation Oncology, Osaka-Izumi, Japan. 16 Kyoto University Graduate School of Medicine, Radiation Oncology and Image-Applied Therapy, Kyoto, Japan

Purpose/Objective:

There are few homogenous prospective results that evaluate survival of patients with early-stage oropharyngeal cancer treated with radiotherapy alone. A single-arm confirmatory phase Ⅲ trial was conducted to evaluate the efficacy and safety for early-stage oropharyngeal cancer (OPC) using the two-step IMRT for dose reduction in the prophylactic irradiation area, and the minimization of the prophylactic irradiation area. (JCOG1208, UMIN-CTR: UMIN000014274)

Material/Methods:

Patients (pts) aged 20-80 years with T1-2N0-1M0 (UICC 7th 2009) OPC (tonsil, base of tongue and soft palate) with performance status 0-1 were enrolled. Chemotherapy was not permitted. As adaptive two-step IMRT, computed tomography planning was performed twice before IMRT for the initial plan of 46 Gy/23 fractions (fr) and during treatment for the boost plan of 24 Gy/12 fr with a total dose of 70 Gy/35 fr. Individual case review of treatment plan was performed. The extent of prophylactic irradiation to the contralateral internal jugular chain was omitted (ipsilateral irradiation) if the primary lesion was the tonsil, and only levels II-III if the base of tongue and soft palate. The primary endpoint was 3-year overall survival (OS). The sample size was 57, with one-sided alpha of 10% and power of 70%, expected and threshold 3-year OS as 90% and 80%. As key secondary endpoints, 3-year loco-regional progression-free survival (PFS) and Grade 2 or more xerostomia score was evaluated. The expected incidences of Grade 2 or more xerostomia at 2 years after IMRT were less than 30%.

Results: