# Differences between Survival Rates and Patterns of Failure of Patients with Lung Adenocarcinoma and Squamous Cell Carcinoma Who Received Single-Fraction Stereotactic Body Radiotherapy

## TL;DR

This study compares outcomes of lung cancer patients treated with single-dose radiation therapy, finding that adenocarcinoma patients are more likely to experience distant cancer spread than squamous cell carcinoma patients.

## Contribution

The study reveals a significant difference in distant failure rates between lung adenocarcinoma and squamous cell carcinoma patients treated with single-fraction SBRT.

## Key findings

- Adenocarcinoma patients had significantly higher distant failure rates compared to squamous cell carcinoma patients.
- No significant differences were found in overall survival, disease-free survival, local failure, or nodal failure between the two histologies.
- The results suggest the need to report outcomes by histology in trials combining SBRT with systemic therapy.

## Abstract

Stereotactic body radiotherapy (SBRT) offers a highly conformal tumoricidal dose of radiation and is an effective treatment for early stage non-small cell lung cancer (NSCLC). Single-fraction SBRT (SF-SBRT) produces cost-effective and comparable outcomes to hypofractionated SBRT regimens. There is a limited understanding of patient outcomes after SF-SBRT according to the histology of their early stage NSCLC. We investigated the survival and patterns of failure of patients with adenocarcinoma (ADC) and squamous cell carcinoma (SCC). Out of the 292 eligible patients, 174 and 118 patients were diagnosed with ADC and SCC, respectively. Patients with ADC were found to be significantly more likely to experience a distant failure compared to patients with SCC. No significant differences were found in overall survival, disease-free survival, local failure, or nodal failure based on histology.

We investigated the survival and patterns of failure in adenocarcinoma (ADC) and squamous cell carcinoma (SCC) in early stage non-small cell lung cancer (NSCLC) treated with single-fraction stereotactic body radiation therapy (SF-SBRT) of 27–34 Gray. A single-institution retrospective review of patients with biopsy-proven early stage ADC or SCC undergoing definitive SF-SBRT between September 2008 and February 2023 was performed. The primary outcomes were overall survival (OS) and disease-free survival (DFS). The secondary outcomes included local failure (LF), nodal failure (NF), and distant failure (DF). Of 292 eligible patients 174 had adenocarcinoma and 118 had squamous cell carcinoma. There was no significant change in any outcome except distant failure. Patients with ADC were significantly more likely to experience distant failure than patients with SCC (p = 0.0081). In conclusion, while SF-SBRT produced similar LF, NF, DFS, and OS, the higher rate of distant failure in ADC patients suggests that ongoing trials of SBRT and systemic therapy combinations should report their outcomes by histology.