Systematic EndoscopIc Staging of Mediastinum to determine Impact on radiotherapy for locally advanced lung Cancer (SEISMIC): interim results from a prospective multicentre interventional study.
D. Steinfort*a (Dr), D. Ostb (Prof), K. Yasufukuc (Dr), J. Annemad (Prof), L. Crombagd (Dr), B. Jenningse (Dr), D. Fieldingf (Dr), P. Nguyeng (Dr), S. Yoe (Dr), K. Rangamuwaa (Dr), P. Leeb (Dr), Y. Shih (Dr), J. Simpsonh (Prof), G. Kotharii (Dr), N. Hardcastlei (Dr), S. Sivai (Dr)
a Royal Melbourne Hospital, Melbourne, AUSTRALIA ; b The University of Texas, MD Anderson Cancer Center, Houston, UNITED STATES ; c Toronto General Hospital, Toronto, CANADA ; d University of Amsterdam, Amsterdam, NETHERLANDS ; e Monash Health, Melbourne, AUSTRALIA ; f Royal Brisbane and Women's Hospital, Brisbane, AUSTRALIA ; g Royal Adelaide Hospital, Adelaide, AUSTRALIA ; h University of Melbourne, Melbourne, AUSTRALIA ; i Peter MacCallum Cancer Centre, Melbourne, AUSTRALIA
Curative-intent treatment of patients with Stage III non-small cell lung cancer (NSCLC) frequently includes radical radiation, with International guidelines recommending radiation fields be constructed based on PET-identified extent of disease. Selective (targeted) LN sampling is most commonly performed. Studies in early stage (Stage I-II) NSCLC confirm systematic mediastinal lymph node (LN) staging with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) improves accuracy of mediastinal staging. We sought to determine the impact of systematic mediastinal LN staging in Stage III using EBUS-TBNA to accurately delineate disease extent.
Consecutive participants with Stage III NSCLC based on clinical imaging underwent systematic LN staging via EBUS-TBNA. (ACTRN12617000333314). Primary study outcome was proportion of patients with PET-occult LN metastases detected by EBUS.
Data was available for 168 of 173 eligible patients at the time of writing. M:F 103:65. Mean age 68+/-9 years.
EBUS demonstrated findings concordant with PET-identified mediastinal LN involvement in 101 (58%) of patients, with discordant findings (primary outcome) observed in 67 (40%) of patients.
PET-occult disease was identified by EBUS in 18 (10.4%) patients, with 11 of these upstaged (9 patients N2 → N3). EBUS identified lesser extent of disease in 49 patients (29%) with 38 (23%) down-staged to N1 (11) and N0 (27). Surgical confirmation of results was performed in 18 of 38, with 100% concordance.
Systematic LN staging via EBUS-TBNA identifies PET-occult LN disease in 10.4% of patients. A significant proportion of patients with cN2/3 NSCLC are confirmed to have pN0/1 following systematic assessment of mediastinal LN.
Further analysis will identify risk factors for identification of PET-occult metastases, and will confirm the impact PET-EBUS discordance in Stage III NSCLC on radiation dosimetry and tumour control probability.
Disclosure of funding source(s): none