ESTRO 2022 - Abstract Book

S1059

Abstract book

ESTRO 2022

Purpose or Objective Bone is one of the most common and earlier site of metastases from non-small cell lung cancer (NSCLC), occurring in about 10% - 35% of cases during the course of disease.The current standard of care for patients with symptomatic bone metastases is a low total dose of radiation delivered with conventional external beam RT. The aim of this retrospective analysis is to explore whether SBRT could improve the local control and the complete response rate for pain compared with conventional external beam RT in oligometastatic bone NSCLC. Materials and Methods Patients with histologically confirmed NSCLC and oligometastatic disease (number of metastases ≤ 5), painful bone metastases (according to the Numerical Rating Scale [NRS]), Karnofsky Performance Status scores ≥ 80 and treated with SBRT vs 3D-CRT between January 2015 and December 2020 with a minimum follow-up of 3 months were included in the study. The primary endpoint was local control measured by radiological and clinical response. Secondary endpoints included complete clinical response rates for pain, QoL and adverse events (including rates or fracture). Results A total of 122 patients met the inclusion criteria either in 3D-CRT group (n=59), SBRT group (n=62) or both (n=1). Seventy percent of the patients presented a number of lesions < 3, in 50 patients (41%) all lesions were treated. Median total dose over all treatment techniques was 24 Gy (IQR 20-25) in a median number of fraction of 5. Clinical characteristics of the patients and clinical and radiological rate of response are summarize in Table 1 . After a median follow-up of 3 months, treatment with SBRT lowers the risk of disease progression by 75% (OR=0.25, CI 95% (0.05-0.90)). However there appears to be no significant association between technique and radiological response at multivariate analysis ( p = .07). For patients with a number of metastases ≥ 3 (30%), SBRT treatment lowers the risk of disease progression by 88% (p= .01). In addition, those who have a total number of lesions ≥ 3 have a 1.9 times higher risk of disease progression (OR=2.91 (0.83- 10.59)). A significant association between technique and clinical response was observed ( p =.02). In fact, 34% of patients (n=22) in SBRT group showed complete clinical response in comparison to 15% (n=15) in 3D-CRT group. Furthermore, there association between BED and clinical response was registered ( p = .04). Independently from the adopted technique, a pain response was observed ( p = .0005) ( Figure 1 ). Adverse events frequency, including fracture rate, in both SBRT and conventional treatment group was not significant.