Main Session
Sep
29
PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care
3503 - Contralateral Hilar Lymph Node Involvement in Stage III Non-Small Cell Lung Cancer: Safety and Efficacy of Definitive Chemoradiotherapy with Volumetric Modulated Arc Therapy
Presenter(s)
Nobuki Imano, MD, PhD - Hiroshima University, Hiroshima, Hiroshima
N. Imano1, D. Kawahara1, T. Kimura2, Y. Yamamoto1, S. Tani1, S. Miyoshi1, T. Matsuura1, T. Katsuta3, I. Nishibuchi3, and Y. Murakami3; 1Department of Radiation Oncology, Hiroshima University Hospital, Hiroshima, Japan, 2Department of Radiation Oncology, Kochi Medical School, Kochi University, Kochi, Japan, 3Department of Radiation Oncology, Graduate School of Biomedical Health Sciences, Hiroshima University, Hiroshima, Japan
Purpose/Objective(s):
Contralateral hilar lymph node involvement in stage III non-small cell lung cancer (NSCLC) represents an N3 subset traditionally considered unsuitable for definitive radiotherapy due to concerns over excessive cardiopulmonary dose. We hypothesized that definitive chemoradiotherapy (CRT) using volumetric modulated arc therapy (VMAT) would achieve acceptable toxicity while maintaining curative survival outcomes in this population.Materials/Methods:
We retrospectively analyzed 30 patients with stage III NSCLC involving contralateral hilar lymph nodes treated with definitive CRT using VMAT from 2013 to 2023. Clinical staging followed the UICC 9th edition, and lymph node stations were defined by the International Association for the Study of Lung Cancer lymph node map. Radiotherapy was delivered using an involved-field technique without elective nodal irradiation. The clinical target volume (CTV) included a 5–10 mm margin to the primary tumor and a 0–5 mm margin to involved lymph nodes. Respiratory motion management was applied when tumor motion exceeded 1 cm using expiratory breath-hold. For patients treated under free breathing, four-dimensional computed tomography (CT) was used to generate the internal target volume (ITV). A 5–7 mm margin was added to create the planning target volume (PTV). Image guidance consisted of daily bony alignment and weekly cone-beam CT. Toxicities were graded according to CTCAE version 5.0. Overall survival (OS), progression-free survival (PFS), and locoregional control (LRC) were estimated using the Kaplan–Meier method.Results:
Median age was 72 years (range, 36–81), and 23 patients were male. Histology included squamous cell carcinoma (n=17), adenocarcinoma (n=11), and others (n=2). Regarding contralateral hilar involvement, all 21 patients with right-sided lung cancer had contralateral station 10L involvement, including 2 with additional station 11L involvement. All 9 patients with left-sided lung cancer had contralateral station 10R involvement, including 2 with additional station 11R involvement. Clinical stage was IIIB in 18 patients and IIIC in 12 patients. The median radiation dose was 66 Gy (range, 60–74). Platinum-based chemotherapy was administered in 29 patients, and 15 received consolidation immune checkpoint inhibitor therapy. With a median follow-up of 58 months among survivors (range, 26–148), 3-year OS, PFS, and LRC rates were 52%, 26%, and 64%, respectively; 5-year rates were 34%, 23%, and 50%. Grade 2/3 radiation pneumonitis occurred in 17%/3%, and grade 2/3 esophagitis occurred in 27%/27%. No other grade =3 nonhematologic toxicities were observed.Conclusion:
Definitive CRT using VMAT for stage III NSCLC with contralateral hilar lymph node involvement demonstrated acceptable toxicity and encouraging survival. These findings suggest that this subset should not be categorically excluded from curative radiotherapy and may represent a potentially treatable population with modern conformal techniques.