The Canada Lymph Node Score Project: A Crossover Trial

Treatment decisions in Non-Small Lung Cancer (NSCLC) are reliant on a thorough staging process that includes imaging with Computed Tomography (CT), Positron Emission Tomography (PET) and Systematic Sampling (SS) of mediastinal lymph nodes (LNs) by Endobronchial Ultrasound Transbronchial Needle Aspiration (EBUS-TBNA). Collectively, the results of these staging procedures dictate whether patients will be treated with surgery, radiation and/or chemotherapy. Current guidelines for SS through EBUS-TBNA mandate the biopsy of at least 3 mediastinal LN stations (4R, 4L and 7) in the chest, even if they appear normal on CT and PET scan. Despite improvements in diagnostic techniques and safety, LN biopsies remain onerous for the patient and costly to our healthcare system. SS is also unreliable, yielding inconclusive pathology results in 42.14% of cases, especially for Triple Normal LNs, which are LNs that appear normal on PET, and CT, and EBUS. In fact, SS results in mostly negative or inconclusive biopsies for Triple Normal LNs, which may be due in part to their very low probability (< 6%) of malignancy. As such, the researchers have proposed to replace the onerous and unreliable process of SS by a simpler Selective Targeted Sampling (STS) staging process. In STS, Triple Normal LNs will not be biopsied, due to the very high negative predictive value (NPV) of malignancy. STS follows the simple notion that only LNs that have the potential to be malignant should be biopsied, whereas LNs which are very likely benign (i.e. Triple Normal LNs) should not be biopsied.

Inclusion criteria

• Age ≥ 18 years
• Both CT and PET scans completed prior to EBUS
• Suspected or confirmed NSCLC requiring mediastinal staging
• cN0-cN1 as indicated by CT and PET scans

Exclusion criteria

• Patients with cN0 disease AND peripheral tumors AND tumor < 2 cm in diameter, as they do not require mediastinal staging
• Evidence of cN2 disease or higher on CT and PET scans