Protocol summary of a randomized phase III study: comparing systemic therapy with and without debulking surgery (primary tumour resection) for clinical stage IVA (cT1-2bN0-1M1a) non-small cell lung cancer with radiologically undetermined pleural dissemination JCOG2103 (DEBULK-LUNG).

In patients with non-small cell lung cancer (NSCLC) who present with radiologically undetermined malignant pleural dissemination or incidental surgical diagnosis of the same, surgery is generally not the preferred option; systemic therapy is favoured. However, there is no consensus on incorporating primary site resection into the treatment plan. Retrospective analyses hint at potential benefits of combining systemic therapy with primary site resection, but prospective studies have yet to confirm these findings. Consequently, we have planned a multicentre, open-label, randomized controlled phase III trial to assess the efficacy of adding primary site resection to standard systemic therapy for stage IVA (cT1-2bN0-1M1a) NSCLC patients with radiologically undetermined pleural dissemination. The primary endpoint is overall survival. We aim to enroll 170 patients from 71 institutions over 5 years. This trial is registered at the Japan Registry of Clinical Trials (jRCT) under study number jRCTs031220666.