Strategies for Reducing False-Positive Screening Results for Intermediate-Size Nodules Evaluated Using Lung-RADS: A Secondary Analysis of National Lung Screening Trial Data

BACKGROUND. Lung-RADS version 1.1 (v1.1) classifies all solid nodules less than 6 mm as category 2. Lung-RADS v1.1 also classifies solid intermediate-size (6 to < 10 mm) nodules as category 2 if they are perifissural and have a triangular, polygonal, or ovoid shape (indicative of intrapulmonary lymph nodes). Additional category 2 criteria could reduce false-positive results of screening examinations. OBJECTIVE. The purpose of this study was to evaluate the impact of proposed strategies for reducing false-positive results for intermediate-size nodules on lung cancer screening CT evaluated using Lung-RADS v1.1. METHODS. This retrospective study entailed secondary analysis of National Lung Screening Trial (NLST) data. Of 1387 solid nodules measuring 6.0-9.5 mm on baseline screening CT examinations in the NLST, all 38 nodules in patients who developed cancer and a random sample of 200 nodules in patients who did not develop cancer were selected for further evaluation. Cancers were required to correspond with the baseline nodule on manual review. After exclusions, the sample included 223 patients (median age, 62 years; 143 men, 80 women; 196 benign nodules, 27 malignant nodules). Two thoracic radiologists independently reviewed baseline examinations to record nodule diameter and volume using semiautomated software and to determine whether nodules had perifissural location; other subpleural location; and triangular, polygonal, or ovoid shape. Different schemes for category 2 assignment were compared. RESULTS. Across readers, standard Lung-RADS v1.1 had sensitivity of 89-93% and specificity of 26-31%. A modification assigning nodules less than 10 mm with triangular, polygonal, or ovoid shape in other subpleural locations (vs only perifissural location) as category 2 had sensitivity of 85-93% and specificity of 47-51%. Lung-RADS v1.1 using volume cutoffs had sensitivity of 89-93% and specificity of 37% (both readers). The sensitivity of both modified Lung-RADS v1.1 and Lung-RADS v1.1 with volume cutoffs was not significantly different from standard Lung-RADS v1.1 (all p > .05). However, both schemes' specificity was significantly better than standard Lung-RADS v1.1 (all p < .05). Combining the two strategies yielded sensitivity of 85-93% and specificity of 58-59%. CONCLUSION. Classifying intermediate-size nodules with triangular, polygonal, or ovoid shape in any subpleural (not just perifissural) location as category 2 and using volume- rather than diameter-based measurements improves Lung-RADS specificity without decreased sensitivity. CLINICAL IMPACT. The findings can help reduce false-positive results, decreasing 6-month follow-up examinations for benign findings.

Intrapulmonary lymph nodes masquerading as pleural metastasis

Intrapulmonary lymph nodes (IPLNs) are a frequent finding of computed tomography for lung cancer and can grow without malignant findings. Linear densities extending from the nodules are a characteristic of IPLNs.

Clinical significance of intrapulmonary lymph node dissection in pathological stage IA non-small cell lung cancer: A propensity score matching analysis

Background

This study aimed to investigate the prognostic impact of intrapulmonary lymph node (ILN, stations 13–14) dissection on disease‐free survival (DFS) in stage IA non‐small cell lung cancer (NSCLC) patients in order to facilitate a more suitable determination of surgical strategies for early‐stage cases.

Methods

We retrospectively analyzed 416 patients with pathological stage IA NSCLC from February 2016 to November 2019. The patients were divided into a group with ILN dissection (ILN^D+ group) and a group without ILN dissection (ILN^D‐ group). DFS was compared using the Kaplan–Meier method and compared statistically using the log‐rank test before and after propensity score matching (PSM). Subgroup analysis of DFS stratified based on tumor size was also calculated.

Results

Both before and after PSM, the four‐year DFS of the ILN^D+ group was greatly increased compared to that of ILN^D‐ group (90.1% vs. 79.7%, p = 0.003; 95.5% vs. 80.6%, p = 0.003, respectively) and multivariable cox regression analysis revealed ILN dissection was an independent factor favoring DFS in stage IA NSCLC (p = 0.016 and p = 0.015, respectively). Subgroup analysis revealed the four‐year DFS was comparable between the ILN ^D+ and ILN^D‐ groups with regard to tumor size ≤1.5 cm (90.6% vs. 92.7%, p = 0.715). However, the ILN ^D+ group was found to have a better oncological outcome compared with the ILN^D‐ group with regard to tumor size >1.5 cm (90.0% vs. 73.8%, p = 0.003).

Conclusions

The prognostic impact of ILN dissection on patients with stage IA NSCLC appears to be significantly influenced by tumor size, and this should be taken into account when choosing the most appropriate therapeutic modality.

Intrapulmonary lymph node metastasis is common in clinically staged IA adenocarcinoma of the lung

BACKGROUND

Intrapulmonary lymph nodes (LNs, stations 11-14) are usually omitted in postoperative pathological examination. Some non-small cell lung cancer (NSCLC) patients with intrapulmonary LN metastasis are incorrectly diagnosed as N0 cases. Furthermore, underestimation of intrapulmonary LN involvement in clinically early stage NSCLC may lead to the incorrect choice of surgical procedure: lobectomy or sublobar resection. This study was conducted to determine the status of intrapulmonary LN involvement in clinically staged IA (c-T1N0M0) peripheral adenocarcinoma of the lung.

METHODS

Seventy-five lobectomy specimens of c-T1N0M0 peripheral adenocarcinoma of the lung were carefully dissected to find intrapulmonary LNs. The longest diameter of each intrapulmonary LN was measured and sent for pathological examination, together with hilar and mediastinal LNs, to investigate the relationship between LN metastasis and primary tumor size.

RESULTS

Intrapulmonary LN metastasis was detected in 22.7%(17/75) of patients. Positive LNs were detected in 21.7% (10/46) of T1b patients and 45% (11/24) of T1c patients, while no metastasis (0/5) was observed in T1a patients (P = 0.036). The mean longest diameter of the 17 involved intrapulmonary LNs was only 6.5 ± 2.1 mm, which was not significantly different to the size of negative intrapulmonary LNs (5.2 ± 1.4 mm).

CONCLUSIONS

Intrapulmonary LN metastasis is common in clinically staged IA peripheral adenocarcinoma of the lung. LN metastasis is related to tumor size, and this should be taken into account to determine appropriate surgical procedures and postoperative treatment. Computed tomography is not a reliable method to judge LN metastasis, particularly intrapulmonary LN metastasis.