Complete endosonographic intrathoracic nodal staging of lung cancer patients in whom SABR is considered.

Accurate staging of lung cancer is important because it directs treatment and
determines prognosis. The development of SABR (high-precision radiotherapy) has
revolutionized radiation therapy for early stage lung cancer and results
demonstrate similar outcomes in comparison to surgical resection of the lung
tumor. Staging work-up program for patients with potentially resectable NSCLC
includes at least CT scans of the chest and integrated PET-CT scans, and when
indicated, (minimally) invasive mediastinal staging. However, patients who are
treated with SABR do not routinely undergo the same nodal staging work-up as do
surgical candidates. As both surgery and SABR appear to achieve comparable
rates of local and regional tumor control, it appears only logical to perform a
similar staging work-up in all patients with early stage lung cancer who will
be treated with either of the two curative local modalities. In the past, a
lack of invasive nodal sampling before SABR was considered acceptable as
invasive surgical staging (mediastinoscopy) was widely considered the preferred
procedure. However, with minimally invasive and safe endosonography procedures
that are currently available, improved pre-treatment staging has become
possible for patient groups who are eligible for SABR, despite the presence of
a high rate of comorbidities.

Complete endosonographic (combined endobronchial and esophageal) staging of
hilar and mediastinal lymph nodes in patients with (suspected) non-small cell
lung cancer (NSCLC) will result in change of loco-regional nodal status in 20%
of patients, in comparison to staging by PET-CT alone.

Prospective, non-randomised diagnostic study. Setting: Multicentre (university
and general hospitals)

The burden and risks associated with participation are considered low. Patients
who will be approached for study participation already have an indication for
mediastinal tissue sampling in accordance with the current lung cancer staging
guidelines. SABR for lung cancer is only considered appropriate when no hilar
or mediastinal nodal metastases are present. We expect that in one out of five
patients, intrathoracic nodal stage will change based on endosonography
outcomes and therefore influence the therapeutic strategy