SBRT for early-stage lung cancer: outcomes from biopsy-proven and unproven lung lesions
Celia Nicolas-Boluda,
Spain
PO-1338
Abstract
SBRT for early-stage lung cancer: outcomes from biopsy-proven and unproven lung lesions
Authors: Celia Nicolas-Boluda1, Gemma Alberca1, Cristina Cigarral1, Enrique Tenllado2, Jorge Hernández2, Katy Aylas3, Alberto Noé4, Ángela Matías1, Luis A. Pérez Romasanta1
1Complejo Asistencial Universitario de Salamanca, Radiation Oncology, Salamanca, Spain; 2Complejo Asistencial Universitario de Salamanca, Radiophysics, Salamanca, Spain; 3Hospital Universitario de Cáceres, Radiation Oncology, Cáceres, Spain; 4Cork University Hospital, Radiation Oncology, Cork, Ireland
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Purpose or Objective
To determine the response and prognosis of patients with early stage medically inoperable biopsy-proven non-small cell lung carcinoma (NSCLC) and suspected primary malignant lesions treated exclusively with stereotactic body radiation therapy (SBRT).
Material and Methods
We performed a retrospective analysis of 86 patients with Stage I - III (T1-4 N0 M0) proven or suspected NSLCL treated between October 2015 and December 2021. Patients treated with SBRT were nonsurgical candidates and/or patients who refused surgery. Advanced-stage T4 lesions were included in the study when all the nodules could be treated at the same time.
Each patient had appropriate pretreatment staging with CT scans and FDG-18 PET-CT. Different motion management methods to account for respiratory motion were performed. Dose-prescription ranged from 55 to 60 Gy in 5 - 8 fractions. Treatment was delivered on Varian True-Beam® or Clinac DHX® linear accelerator, using volumetric modulated arc therapy (VMAT) with 6MV photons. Image guidance (IGRT) was performed by means of CBCT acquisitions prior to each treatment. After treatment, patients were followed with CTs or PET/CTs at least every 3 months for 2 year and every 6 months thereafter.
The primary endpoints were Tumor Response, assessed via RECIST criteria, Local Control (LC), Disease-Free Survival(DFS), Overall Survival (OS) and treatment-related toxicity. The Kaplan Meir method and Log-Rank test were used to analyse the survival curves on SPSS v 25.0 (IBM Corp) was used for statistical analyses.
Results
Median age at treatment was 75 years (range 49 to 89 years), 82.5% males. The proportion of adenocarcinoma, squamous cell carcinoma, and unproven pathology was 36%, 25.6%, and 24.4% respectively. Most patients were early-stage (T1 69.8%; T2 19.8%), and the remaining 10.5% were T3-T4. The right upper lobe was the most involved (43%) whilst the right lower lobe was the least affected (7%).
With a median follow-up of 19 months (range 1 to 80 months), the overall survival (OS) at 2y was 76%. The 2y OS rates for patients treated with T1compared to T2 lesions were 80% vs 76% (p=0.207). For early-stage and advanced cases 2y OS rates were 77% vs 58% respectively (p=0.926). When comparing OS in biopsy-proven vs unproven, the 2y OS rates were 82% vs 75% (p=0.407).
The disease-free survival (DFS) was 72% at 2y; out of the 35 patients who relapsed a 62.8% presented local recurrence, 28.6% distant relapse (brain, liver and nodal) and 8.6% both local and distant disease. The 2y DFS for patients treated with T1 compared to T2 lesions was 50% vs 46% (p=0.750). The 2y DFS for advanced-stage and early-stage cases was 67% and 78% respectively (p=0.926). For patients with or without biopsy the 2y DFS rate was 52% and 43% respectively (p=0.506).
Conclusion
Outcomes after exclusive treatment with SBRT in patients with NSCLC are satisfactory with no disadvantage for empirically treated patients.