Background: At the time of endobronchial ultrasound (EBUS) staging, ultrasonographic features can be used to predict mediastinal lymph node (LN) malignancy. Predictive tools have been developed, however they have not gained widespread use due to lack of research demonstrating validity and reliability. We sought to develop a novel predictive tool, the Canada Score, capable of predicting malignancy and potentially guide LN biopsy decision making. Methods: We prospectively analyzed the ultrasonographic features of LNs from patients with NSCLC. Ultrasonographic features were identified by a single experienced endoscopist, this data was used to develop the Canada Score. Pathological specimens were used as the gold standard for determination of malignancy. Videos were then circulated to endoscopists across Canada, who were also asked to identify ultrasonographic features for each LN. Hosmer- Lemeshow test, logistic regression, receiver operator characteristic (ROC) curve, and Gwet’s AC1 analyses were used to test the performance, discriminatory capacity, and inter-rater reliability of the Canada Score. Results: A total of 300 LNs from 140 patients were analyzed by 12 endoscopists across 7 Canadian centres. Backwards elimination was used to create a multivariate model. Hosmer-Lemeshow test and ROC curves indicated the model was well-calibrated (chi2=11.86, p=0.1567) with good discriminatory power (c- statistic= 0.72 ±0.042, 95%CI: 0.64-0.80). Beta-coefficients were used to create a simplified score out of four. Evaluation of the tool showed that LNs scoring 3 or 4 had odds ratios of 15.17 (p<0.0001) and 50.56 (p=0.001), respectively for predicting malignancy. A score of 4/4 was associated with 99.59% specificity and a positive likelihood ratio of 22.78. Inter-rater reliability for a score ≥ 3 was 0.81 ± 0.02 (95%CI: 0.77-0.85). Conclusions: The Canada Score shows excellent performance in identifying malignant LN at the time of EBUS. A cut-off of ≥ 3 has the potential to inform decision-making regarding biopsy or repeat/mediastinoscopy if the initial results are inconclusive. / Thesis / Master of Science (MSc) / During lymph node staging for lung and esophageal cancer, specific features of lymph nodes can be seen. Using diagnostic tools these features can be used to predict whether a lymph node is cancerous or benign. However, many of these diagnostic tools are inaccurate or unreliable. To address this, this thesis aimed to develop a novel diagnostic tool based on lymph node features seen during staging procedures and determine its clinical usefulness and application to the wider lung and esophageal cancer population. This thesis also aimed to use improved methods to develop this diagnostic tool such that patient and clinician experiences would be significantly improved. The results of this thesis may contribute to a reduction in the number of repeat procedures required for patients undergoing staging prior to their treatment for lung and esophageal cancers.

Background: The standard of care for mediastinal staging during endobronchial ultrasound (EBUS) is Systematic Sampling (SS) where a minimum of 3 lymph node (LN) stations are biopsied, even if they appear normal on imaging. When LNs appear normal on PET and CT, the Canada Lymph Node Score can also identify if they appear normal on EBUS. For these Triple Normal LNs, the pretest probability of malignancy is < 6%, and routine biopsy may not be required. This preliminary study introduced Selective Targeted Sampling (STS), which omits biopsy of Triple Normal LNs and compared it firsthand to SS. Methods: A prospective, feasibility RCT was conducted to determine whether the progression of a definitive trial was warranted. Primary outcomes and their progression criterium were recruitment rate (70% acceptable minimum); procedure length (no overlap between sampling methods’ 95%CIs); and missed nodal metastasis (overlap between sampling methods’ diagnostic accuracy 95%CIs and crossing of the null for the percent difference in diagnosis). cN0-N1 NSCLC patients undergoing EBUS were randomized to the STS or SS arm. Patients in the STS arm were then crossed over to the SS arm to receive standard of care. Wilson’s CI method and McNemar’s test of paired proportions were used for statistical comparison. Surgical pathology was the reference standard. Results: Thirty-eight patients met the eligibility criteria, and all were recruited (100%; 95%CI: 90.82 to 100.00%). The median procedure lengths, in minutes, for STS and SS were 3.07 (95%CI: 2.33 to 5.52) and 19.07 (95%CI: 15.34 to 20.05) respectively. STS had a diagnostic accuracy of 100% (95%CI: 74.65% to 100.00%), whereas SS was 93.75% (95%CI: 67.71% to 99.67%) with the inclusion of inconclusive results. Percent difference in diagnosis between sampling method was 5.35% (95%CI: -0.54% to 11.25%). Conclusion: With the progression criteria successfully met, a subsequent multicentered, non-inferiority crossover trial comparing STS to SS is warranted. / Thesis / Master of Science (MSc) / Before deciding on treatment for patients with lung cancer, a critical step in the investigations is finding out whether the lymph nodes in the chest contain cancer. This is best done with a needle that biopsies those lymph nodes through the walls of the airway, known as endobronchial ultrasound transbronchial needle aspiration. Guidelines require that every lymph node in the chest be biopsied through a process called Systematic Sampling. However, new research has suggested that some lymph nodes may not need a biopsy. These lymph nodes are ones with a very low chance of cancer, based on their imaging tests. In this study, Selective Targeted Sampling was introduced whereby lymph nodes that appeared normal were not initially biopsied. The study followed a feasibility design, which proved sufficient patient interest, adequate safety and possible benefits in pursuing a larger trial comparing Selective Targeted Sampling to Systematic Sampling.

No description available.