# Prognostic Impact of Tumor Solid Components in Stereotactic Body Radiotherapy for Clinical Stage Tis–1N0M0 Lung Cancer

## TL;DR

This study found that lung cancer patients treated with SBRT had better outcomes if their tumors had lower consolidation tumor ratios and were smaller.

## Contribution

The study identifies CTR and tumor stage as key prognostic factors for SBRT outcomes in early-stage lung cancer.

## Key findings

- Patients with CTR ≤ 0.25 had no recurrences, metastases, or deaths.
- T1a tumors showed significantly better progression-free survival than T1b–c tumors.
- CTR > 0.25 and larger PTV were linked to worse progression-free survival.

## Abstract

This study aimed to assess the potential of prognostic factors including consolidation tumor ratio (CTR) on treatment outcomes in patients with clinical stage 0–IA non‐small cell lung cancer (NSCLC) undergoing stereotactic body radiotherapy (SBRT).

The analysis included data of 63 patients with 67 lesions of clinical stage 0–IA NSCLC treated with SBRT. According to the Union for International Cancer Control 8th edition, the following tumor stages were observed: Tis, 3; T1mi, 2; T1a, 11; T1b, 29; and T1c, 22. The prescribed dose was 48 (range, 42–52) Gy in four fractions.

The median follow‐up was 29.3 (range: 2.4–120.5) months. The five‐year local control (LC), overall survival, and progression‐free survival (PFS) rates were 89.4%, 60.3%, and 40.5%, respectively. Squamous cell carcinoma (Sq) and Dmax < 125 GyBED10 for planning target volume (PTV) were associated with a worse LC (p = 0.001 and 0.017, respectively). Patients with Sq, T1b–c, CTR > 0.25, PTV ≥ 30 cm3 tumors were associated with worse PFS than those with non‐Sq, ≤ cT1a, CTR ≤ 0.25, PTV < 30 cm3 tumors (p = 0.049, 0.004, 0.038, and 0.004, respectively). No recurrences, metastases, or deaths were found in patients with CTR ≤ 0.25 (n = 5).

In patients with stage 0–IA lung cancer treated with SBRT, tumors classified as ≤ T1a showed a better PFS than T1b–c. NSCLC with a low CTR of ≤ 0.25 seemed to have a low risk of recurrence after SBRT.

Progression‐free survival (PFS) per T stage and consolidation tumor ratio (CTR) in all eligible patients.
PFS for patients per T stage. Patients with tumors of cT1a or less showed significantly better PFS than those with cT1b or c (n = 13 and 50 in cT1a or less and cT1b and c groups, respectively; p = 0.004).PFS for patients per CTR. Patients with tumors of CTR ≤ 0.25 showed significantly better PFS than those with > 0.25 (n = 5 and 58 in CTR ≤ 0.25 and > 0.25 groups; p = 0.038).

PFS for patients per T stage. Patients with tumors of cT1a or less showed significantly better PFS than those with cT1b or c (n = 13 and 50 in cT1a or less and cT1b and c groups, respectively; p = 0.004).

PFS for patients per CTR. Patients with tumors of CTR ≤ 0.25 showed significantly better PFS than those with > 0.25 (n = 5 and 58 in CTR ≤ 0.25 and > 0.25 groups; p = 0.038).