The Canada Lymph Node Score Project: A Crossover Trial

Overview

Before deciding on treatment for patients with lung cancer, a critical step in the investigation is finding out whether the lymph nodes in the chest contain cancer cells. This is accomplished with a biopsy of the lymph nodes through the airway wall, known as Endobronchial Ultrasound-guided Transbronchial Needle Aspiration. Guidelines require that every single lymph node in the chest be biopsied through a process called Systematic Sampling. However, emerging data suggests that the lymph nodes that appear benign on imaging and ultrasound do not need a biopsy. A proposed alternative to the inefficient Systematic Sampling is the simplified Selective Targeted Sampling of the lymph nodes, whereby only lymph nodes that look malignant are biopsied. This trial will evaluate the simplified Selective Targeted Sampling of lymph nodes and compare it to Systematic Sampling to see whether it is equally as effective in staging lung cancer.

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.