What are your PFT thresholds before definitive radiation for NSCLC?

Dear colleagues, I am interested to know your experience/institutional guidelines on how to set PFT (FEV1, FEV1/FVC, TLC, DLCO) thresholds below which you refuse radical radiation to an 80 years old, fit patient, clinically not dyspneic nor depending on oxygen who presents with left lower lobe T3N0 NSCLC invading ribs and chest wall (<5cm)... What are your PFT thresholds before definitive radiation for NSCLC?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: Radiation Oncology Source Type: forums