Efficacy of immune checkpoint inhibitor monotherapy for patients with massive non-small-cell lung cancer.

Baseline tumor size (BTS) and the presence of massive lesions are important for predicting the clinical course of cancer. However, their impact on survival and clinical response in patients with advanced NSCLC undergoing immune checkpoint inhibitor (ICI) treatment has been scarcely investigated. We retrospectively reviewed 294 patients who underwent ICI therapy for advanced or recurrent non-small-cell lung cancer (NSCLC) between January 2016 and July 2019. Of these 294 patients, 284 (96.6%) had at least one measurable lesion. Of these, 263 patients treated with ICI monotherapy were included in the analysis. The median total and maximum target lesion diameters were 96.5 mm and 49.1 mm, respectively. Median progression-free survival (PFS) with massive lesions (max BTS > 50 mm, group A) and without massive lesions (max BTS ≤ 50 mm, group B) was 2.5 months (95% CI 1.8-3.7) and 6.7 months (95% CI 5.1-9.7), respectively. Median overall survival (OS) for groups A and B was 9.5 months (95% CI 5.5-12.3) and 20.0 months (95% CI 13.3-32.0), respectively. The multivariate analysis revealed marked associations between the presence of massive lesions and both PFS and OS. The presence of massive lesions (max diameters > 50 mm) is an independent prognostic factor in advanced NSCLC treated with ICI monotherapy. Although overall response rates were similar between groups A and B, the disease control rate was significantly poorer for group A. Max BTS might be useful for predicting clinical outcomes for patients undergoing immunotherapy as a parameter reflecting their tumor burden.