Segmentectomy for ground-glass-dominant lung cancer with a tumour diameter of 3 cm or less including ground-glass opacity (JCOG1211): a multicentre, single-arm, confirmatory, phase 3 trial.

Background: Although segmentectomy is a widely used surgical procedure, lobectomy is the standard procedure for resectable non-small-cell lung cancer (NSCLC). This study aimed to evaluate the efficacy and safety of segmentectomy for NSCLC up to 3 cm in size, including ground-glass opacity (GGO) and predominant GGO.

Methods: A multicentre, single-arm, confirmatory phase 3 trial was conducted across 42 institutions (hospitals, university hospitals, and cancer centres) in Japan. Segmentectomy with hilar, interlobar, and intrapulmonary lymph node dissection was performed as protocol surgery for patients with a tumour diameter of up to 3 cm, including GGO and dominant GGO. Eligible patients were those aged 20-79 years with an Eastern Cooperative Oncology Group performance score of 0 or 1 and clinical stage IA tumour confirmed by thin-sliced CT. The primary endpoint was 5-year relapse-free survival (RFS). This study is registered with the University Hospital Medical Information Network Clinical Trials (UMIN000011819), and is ongoing.

Findings: A total of 396 patients were registered from Sept 20, 2013, to Nov 13, 2015, of whom 357 underwent segmentectomy. At a median follow-up of 5·4 years (IQR 5·0-6·0), the 5-year RFS was 98·0% (95% CI 95·9-99·1). This finding exceeded the 87% of the pre-set threshold 5-year RFS and the primary endpoint was met. Grade 3 or 4 early postoperative complications occurred in seven patients (2%), but no grade 5 treatment-related deaths occurred.

Interpretation: Segmentectomy should be considered as part of standard treatment for patients with predominantly GGO NSCLC with a tumour size of 3 cm or less in diameter, including GGO even if it exceeds 2 cm.

Funding: National Cancer Centre Research and Development Fund and Japan Agency for Medical Research and Development.