Background
Systemic chemotherapy for lung cancer, especially non-squamous non-small cell lung cancer (NSCLC), must be selected in consideration of the decline in organ function due to aging. In this study, we examined the actual age-based regimen selection and its associated prognosis.

Patients and Methods
We retrospectively evaluated patients who had been diagnosed and initially treated for non-squamous (Sq) NSCLC between January 2017 and July 2022 at our institution. Our objective was to determine the differences in the proportion of patients with impaired renal function between elderly and non-elderly patients, and the associated impact on regimen selection and survival.

Results
We included 164 patients, comprising 85 men and 79 women, with a median age of 71 (range, 39?94) years. Renal dysfunction was significantly more common in the elderly (8.0% vs. 35.3%, p=0.001). Elderly patients were predominantly less likely to choose a regimen of cytotoxic anticancer agents ± immune checkpoint inhibitors (ICIs) than non-elderly patients (p=0.032). In particular, regimens containing pemetrexed tended to be used less frequently in the elderly (p=0.053). Conversely, ICI monotherapy tended to be used more frequently in the elderly (p=0.102). No significant difference was observed in progression-free survival or overall survival based on renal function.

Conclusions
Renal dysfunction was significantly more common in elderly patients with non-Sq NSCLC. A relationship between age and regimen was observed in these patients.