Table 4.

Schema for defining mediastinal GTV in NSCLC

Nodal diameter (short axis)	PET status	Approach	Comment
<1 cm	+	Include in GTV	Positive predictive value higher for PET than CT, biopsy when possible
<1 cm	–	Exclude from GTV	High negative predictive value for PET, small probability of N2 disease
>1 cm	+	Include in GTV unless pathology is negative	Sensitivity for TBNA is inferior to EBUS or EUS-TBNA
1–1.5 cm (no cytology available)	–	Exclude from GTV if primary tumor is PET-positive, unless cytology or histology is positive	High negative predictive value for PET, small probable (5%) of N2 disease
>1.5 cm	–	Include in GTV	21% probability of N2 disease

GTV, gross tumor volume; NSCLC, non-small cell lung cancer; PET, positron emission tomography; CT, computed tomography; TBNA, transbronchial needle aspiration; EBUS, endobronchial ultrasound; EUS, endoscopic ultrasound.