RESUMO
OBJECTIVES: Patients suitable for radical chemoradiotherapy for lung cancer routinely have radiotherapy (planning) volumes based on positron emission tomography (PET)-computed tomography (CT) imaging alone. Endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) can identify PET-occult malignancy and benign PET-avid regions. We investigated the impact of EBUS-TBNA on curative-intent radiotherapy in non-small cell lung cancer (NSCLC). METHODS: A prospective multicentre trial was undertaken, investigating the impact of systematic EBUS-TBNA in addition to PET-CT for patients considered for radical chemoradiotherapy with NSCLC. A subset analysis of patients with discordant findings between PET-CT and EBUS-TBNA was performed. Radiotherapy plans investigated tumour coverage and dose to critical organs at risk (OARs) using PET-CT alone in comparison to PET-CT and EBUS-TBNA. RESULTS: Of 30 patients enrolled, 10 had discordant findings between PET-CT and EBUS-TBNA. EBUS-TBNA-derived plans allowed for reduction in dose to OARs in patients downstaged by EBUS-TBNA, and reduced the risk of geographic miss in treating PET-occult disease in four patients where EBUS-TBNA identified malignant involvement of PET-negative lymphadenopathy. With the addition of EBUS-TBNA to radiotherapy planning, reductions were noted of 5.7%, 3.7% and 12.5% for the risks of symptomatic pneumonitis, mean heart dose and mean oesophageal dose, respectively. CONCLUSIONS: This study demonstrates for the first time that systematic EBUS-TBNA prior to radical-intent radiotherapy significantly improves coverage of subclinical disease through detection of PET-occult metastases. Identification of false-positive lymph node involvement in highly selected cases may reduce radiation dose to critical structures, and risk of organ toxicity.
RESUMO
BACKGROUND AND PURPOSE: To assess the utility of functional lung avoidance using IMRT informed by four-dimensional (4D) ventilation/perfusion (V/Q) PET/CT. MATERIALS AND METHODS: In a prospective clinical trial, patients with non-small cell lung cancer (NSCLC) underwent 4D-V/Q PET/CT scanning before 60Gy of definitive chemoradiation. Both "highly perfused" (HPLung) and "highly ventilated" (HVLung) lung volumes were delineated using a 70th centile SUV threshold, and a "ventilated lung volume" (VLung) was created using a 50th centile SUV threshold. For each patient four IMRT plans were created, optimised to the anatomical lung, HPLung, HVLung and VLung volumes, respectively. Improvements in functional dose volumetrics when optimising to functional volumes were assessed using mean lung dose (MLD), V5, V10, V20, V30, V40, V50 and V60 parameters. RESULTS: The study cohort consisted of 20 patients with 80 IMRT plans. Plans optimised to HPLung resulted in a significant reduction of functional MLD by a mean of 13.0% (1.7Gy), p=0.02. Functional V5, V10 and V20 were improved by 13.2%, 7.3% and 3.8% respectively (p-values<0.04). There was no significant sparing of dose to functional lung when adapting to VLung or HVLung. Plan quality was highly consistent with a mean PTV D95 and D5 ranging from 60.8Gy to 61.0Gy and 63.4Gy to 64.5Gy, respectively, and mean conformity and heterogeneity index ranging from 1.11 to 1.17 and 0.94 to 0.95, respectively. CONCLUSION: IMRT plans adapted to perfused but not ventilated lung on 4D-V/Q PET/CT allowed for reduced dose to functional lung whilst maintaining consistent plan quality.
