Influence of Ground Glass Opacity and the Corresponding Pathological Findings on Survival in Patients with Clinical Stage I Non–Small Cell Lung Cancer

Differences in the prognostic implication of ground-glass opacity on CT according to pathological nodal status in lung cancers treated with lobectomy or pneumonectomy

OBJECTIVES

To clarify the prognostic significance of a ground-glass opacity (GGO) component according to T category and pathological nodal status in patients with resectable non-small cell lung cancer (NSCLC).

METHODS

Patients who underwent lobectomy or pneumonectomy for NSCLC between July 2010 and December 2017 were retrospectively included. Patients were divided into GGO and solid groups based on the presence of a GGO component on CT. The effects on survival of interactions between GGO and (a) pathological nodal status (pN) and (b) cT category were evaluated using Cox regression.

RESULTS

Out of 1545 patients, 548 were classified into the GGO group (pN0: 457, pN1/2: 91) and 997 into the solid group (pN0: 660, pN1/2: 337). There were interactions between the presence of GGO and pathological nodal status on 5-year disease-free survival (DFS; p = .006) and 5-year overall survival (OS; p = .02). In multivariate analysis, better survival of patients in the GGO group than in the solid group was observed only in pN0 category (adjusted hazard ratio [HR], 0.63 for 5-year DFS; p = .002 and 0.47 for 5-year OS; p = .002), but not in pN1/2 category. Moreover, in those with pN0 category, the favorable prognostic value of GGO was limited to those with cT1 category for 5-year DFS (adjusted HR, 0.48; p < .001) and those with cT1/2 category for 5-year OS (adjusted HR, 0.37; p = .002).

CONCLUSIONS

GGO was a favorable predictor of survival only in patients with pN0 category, showing an advantage in DFS for those with cT1 category and OS for those with cT1/2 category.

KEY POINTS

• The presence of ground-glass opacity was associated with a favorable prognosis, only in pathological node-negative patients (5-year disease-free survival, p = .002; 5-year overall survival, p = .002). • Within pathological node-negative patients, the effect of ground-glass opacity on 5-year disease-free survival was valid in patients with cT1 category (adjusted hazard ratio, 0.48; 95% confidence interval, 0.32-0.72; p < .001), but not in patients with cT2 or above category. • Within pathological node-negative patients, the effect of ground-glass opacity on 5-year overall survival was valid in patients with cT1/2 category (adjusted hazard ratio, 0.37; 95% confidence interval, 0.20-0.68; p = .002), but not in patients with cT3/4 category.

Latest Clinical Evidence and Operative Strategy for Small-Sized Lung Cancers

Many thoracic surgeons revealed that consolidation tumor ratio or solid component size on thin-section computed tomography has been considered more prognostic than maximum tumor size in non-small cell lung cancer (NCSLC). According to the results, the 8th TNM classification drastically changed the staging system, i.e., clinical T category was determined based on the invasive or solid component size excluding a ground-glass opacity (GGO). However, several debates are arising over the application of radiological solid size for the clinical T staging. Meanwhile, recent several institutional reports have noticed a significantly simple fact that the presence of a GGO denotes an influence on the favorable prognosis of NSCLC. More important, radiologic pure-solid lung cancers without a GGO exhibit more malignant behaviors with regard to both the clinical and pathological aspects, and show several histologic types that have a poorer prognosis than radiologic part-solid lung cancer. In contrast, favorable prognostic impact of the presence of a GGO component was demonstrated, which was irrespective of the solid component size in cases in which the tumor showed a GGO component. Recently, this concept has been gradually noticed on a nationwide level. Obvious distinctions regarding the several baseline characteristics between the tumor with/without GGO component is a fundamental biological feature of early-stage lung cancer, which would result in a big difference in prognosis, modes of recurrence, overall behavior, and appropriate operative strategies. As a future perspective, the presence or absence of a GGO should be considered as an important parameter in the next clinical T classification.

Development of a deep learning-based method to diagnose pulmonary ground-glass nodules by sequential computed tomography imaging

Background

Early identification of the malignant propensity of pulmonary ground‐glass nodules (GGNs) can relieve the pressure from tracking lesions and personalized treatment adaptation. The purpose of this study was to develop a deep learning‐based method using sequential computed tomography (CT) imaging for diagnosing pulmonary GGNs.

Methods

This diagnostic study retrospectively enrolled 762 patients with GGNs from West China Hospital of Sichuan University between July 2009 and March 2019. All patients underwent surgical resection and at least two consecutive time‐point CT scans. We developed a deep learning‐based method to identify GGNs using sequential CT imaging on a training set consisting of 1524 CT sections from 508 patients and then evaluated 256 patients in the testing set. Afterwards, an observer study was conducted to compare the diagnostic performance between the deep learning model and two trained radiologists in the testing set. We further performed stratified analysis to further relieve the impact of histological types, nodule size, time interval between two CTs, and the component of GGNs. Receiver operating characteristic (ROC) analysis was used to assess the performance of all models.

Results

The deep learning model that used integrated DL‐features from initial and follow‐up CT images yielded the best diagnostic performance, with an area under the curve of 0.841. The observer study showed that the accuracies for the deep learning model, junior radiologist, and senior radiologist were 77.17%, 66.89%, and 77.03%, respectively. Stratified analyses showed that the deep learning model and radiologists exhibited higher performance in the subgroup of nodule sizes larger than 10 mm. With a longer time interval between two CTs, the deep learning model yielded higher diagnostic accuracy, but no general rules were yielded for radiologists. Different densities of components did not affect the performance of the deep learning model. In contrast, the radiologists were affected by the nodule component.

Conclusions

Deep learning can achieve diagnostic performance on par with or better than radiologists in identifying pulmonary GGNs.

Prognostic stratification according to size and dominance of radiologic solid component in clinical stage IA lung adenocarcinoma

Introduction

Although several studies have investigated the prognostic significance of the radiographic appearance of stage IA lung adenocarcinoma, the prognostic impact of solid component size or consolidation-to-tumor ratio (CTR) of part-solid nodules (PSNs) still remains controversial. This study aimed to clarify the combined prognostic impact of the mentioned radiographic features of PSNs and compare it with that of pure solid nodules in the current TNM classification.

Methods

We retrospectively investigated 1014 patients with clinical stage IA (TNM eighth edition) adenocarcinoma who underwent curative resection. Overall survival (OS) and pathologic characteristics of pure solid nodules, solid-dominant PSNs (CTR > 0.5), and ground-glass opacity (GGO)-dominant PSNs (CTR ≤ 0.5) were compared according to T category.

Results

Patients with pure solid nodules (297 cases) had significantly shorter OS compared with those with PSNs (717 cases) (p < 0.001) but a marginal difference compared with those with solid-dominant PSNs (286 cases) (p = 0.051). No significant difference in OS was found according to T category in those with GGO-dominant PSNs (431 cases). Patients with cT1b and T1c solid-dominant PSNs had significantly worse prognosis compared with those with other PSNs and had comparable prognosis with those with cT1b pure solid nodules (p = 0.892). Higher frequency of nodal and lymphovascular involvement and pathologic upstaging was observed with T category progression in solid-dominant PSNs.

Conclusions

An hierarchy of prognosis and pathologic malignant characteristics was observed according to T category in patients with solid-dominant PSNs but not in those with GGO-dominant PSNs, suggesting the importance of classifying PSNs on the basis of solid component size and CTR for accurate prognostic comparison with pure solid nodules.

Pan-Driver-Negatives <i>versus</i> Epidermal Growth Factor Receptor Mutants for C-Stage IA Lung Adenocarcinoma with Ground-Glass Opacity

Purpose: We aimed to verify the prognosis of epidermal growth factor receptor (EGFR) mutation of clinical (c)-stage IA lung adenocarcinoma with the ground-glass opacity (GGO) component.

Methods: We evaluated 226 cases of surgically resected c-stage IA lung adenocarcinoma with GGO component. Endpoints were overall survival (OS) and recurrence-free survival (RFS). Kaplan–Meier analysis and the log-rank test were used to estimate the survival differences. Prognostic factors were assessed using the univariable and multivariable Cox proportional hazards model.

Results: Among the 226 cases, 177 cases harbored the EGFR-mutant adenocarcinoma with the GGO component. The mean duration of follow-up time was 54.4 ± 1.2 months. The 5-year OS and RFS did not differ significantly between the EGFR-mutant and wild-type groups (5-year OS 100% vs. 94.3%, hazard ratio [HR] 0.276, P = 0.168; 5-year RFS 94.7% vs. 95.7%, HR 0.873, P = 0.864). Multivariable Cox hazard model revealed that radiologically solid component size (P = 0.010) and pathological node-positive (P = 0.036) were significant predictors of an inferior RFS.

Conclusion: EGFR-mutant was not a prognostic factor of OS and RFS for c-stage IA lung adenocarcinoma with the GGO component. Radiologically solid component size and pathological lymph node status were independent prognostic factors of worse RFS.

Prognostic Nomograms Based on Ground Glass Opacity and Subtype of Lung Adenocarcinoma for Patients with Pathological Stage IA Lung Adenocarcinoma

The value of lung adenocarcinoma (LUAD) subtypes and ground glass opacity (GGO) in pathological stage IA invasive adenocarcinoma (IAC) has been poorly understood, and reports of their association with each other have been limited. In the current study, we retrospectively reviewed 484 patients with pathological stage IA invasive adenocarcinoma (IAC) at Sun Yat-sen University Cancer Center from March 2011 to August 2018. Patients with at least 5% solid or micropapillary presence were categorized as high-risk subtypes. Independent indicators for disease-free survival (DFS) and overall survival (OS) were identified by multivariate Cox regression analysis. Based on these indicators, we developed prognostic nomograms of OS and DFS. The predictive performance of the two nomograms were assessed by calibration plots. A total of 412 patients were recognized as having the low-risk subtype, and 359 patients had a GGO. Patients with the low-risk subtype had a high rate of GGO nodules (p < 0.001). Multivariate Cox regression analysis showed that the high-risk subtype and GGO components were independent prognostic factors for OS (LUAD subtype: p = 0.002; HR 3.624; 95% CI 1.263–10.397; GGO component: p = 0.001; HR 3.186; 95% CI 1.155–8.792) and DFS (LUAD subtype: p = 0.001; HR 2.284; 95% CI 1.448–5.509; GGO component: p = 0.003; HR 1.877; 95% CI 1.013–3.476). The C-indices of the nomogram based on the LUAD subtype and GGO components to predict OS and DFS were 0.866 (95% CI 0.841–0.891) and 0.667 (95% CI 0.586–0.748), respectively. Therefore, the high-risk subtype and GGO components were potential prognostic biomarkers for patients with stage IA IAC, and prognostic models based on these indicators showed good predictive performance and satisfactory agreement between observational and predicted survival.

Prognosis of epidermal growth factor receptor-mutated stage I lung adenocarcinoma with radiologically solid features

OBJECTIVES

The prognostic role of the epidermal growth factor receptor (EGFR) mutation remains controversial, especially in early-stage lung adenocarcinoma with a solid appearance. We evaluated the oncological outcomes of clinical stage I (c-stage I) radiologically invasive lung adenocarcinoma by EGFR mutation status.

METHODS

Between 2008 and 2013, the data from 463 surgically resected c-stage I radiologically invasive, i.e. solid-dominant lung adenocarcinomas subjected to EGFR mutant analysis, were evaluated. Oncological outcomes were assessed using multivariable Cox regression analysis. Recurrence-free survival (RFS) was estimated using Kaplan-Meier analysis and the log-rank test.

RESULTS

A total of 229 (49%) samples harboured the EGFR-mutant adenocarcinoma. Overall, the 5-year RFS did not differ significantly between the EGFR-mutant and EGFR wild-type groups (67.3% vs 64.9%; P = 0.639). However, among the clinical T1c/T2a tumour subset (n = 177), a multivariable Cox hazard model revealed that radiologically pure-solid tumour (P = 0.024), EGFR-mutant (P = 0.027) and pathological stage II/III (P < 0.001) were significant predictors of a poor RFS. Furthermore, in the c-T1c/T2a radiologically pure-solid lung adenocarcinoma subset, the EGFR-mutant group showed marginally lower 5-year RFS compared to that with the EGFR wild-type group (n = 134; 34.9% vs 53.0%; P = 0.062). Among them, multivariable Cox regression analysis revealed that EGFR mutant (P = 0.037) and pathological stage II/III (P = 0.011) were independently and significantly prognostic for worse RFS.

CONCLUSIONS

Among the c-stage I radiologically invasive lung adenocarcinomas, the EGFR mutation-positive type was correlated with an increased risk of recurrence in the c-T1c/T2a radiologically pure-solid tumour subset. When considering the prognostic value of EGFR mutations in early-stage lung adenocarcinoma, it is necessary to stratify them based on the presence of a ground-glass opacity component.

Radiomics for Survival Risk Stratification of Clinical and Pathologic Stage IA Pure-Solid Non-Small Cell Lung Cancer

Background Radiomics-based biomarkers enable the prognostication of resected non-small cell lung cancer (NSCLC), but their effectiveness in clinical stage and pathologic stage IA pure-solid tumors requires further determination. Purpose To construct an efficient radiomics signature for survival risk stratification personalized for patients with clinical stage and pathologic stage IA pure-solid NSCLC. Materials and Methods In this retrospective study, six radiomics signatures were constructed for patients with stage IA pure-solid NSCLC who underwent resection between January 2011 and December 2013 at authors' institution and were tested in the radiogenomics data set. The radiomics features were extracted from the intratumoral two-dimensional region, three-dimensional volume, and peritumoral area using PyRadiomics. The discriminative abilities of the signatures were quantified using the area under the time-dependent receiver operating characteristic curve (AUC), and the optimal signature was selected for patient stratification. Results The study included 592 patients with stage IA pure-solid NSCLC (median age, 61 years; interquartile range, 55-66 years; 269 women) for radiomics analysis: 381 patients for training, 163 for internal validation, and 48 for external validation. The radiomics signature combining three-region features yielded the highest 3- and 5-year AUCs of 0.77 and 0.78, respectively, in the internal validation set and 0.76 and 0.75, respectively, in the external validation set. Multivariable analysis suggested that the radiomics signature remained an independent prognostic factor (hazard ratio, 6.2; 95% CI: 3.5, 11.0; P < .001) and improved the discriminative ability and clinical usefulness of conventional clinical predictors. Conclusion The radiomics signature with multiregional features helped stratify the survival risk of patients with clinical stage and pathologic stage IA pure-solid non-small cell lung cancer. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Hsu and Sohn in this issue.

Prognostic influence of a ground-glass opacity component in hypermetabolic lung adenocarcinoma

OBJECTIVES

We evaluated the oncological role of a ground-glass opacity (GGO) component in hypermetabolic lung adenocarcinoma with a high maximum standardized uptake value.

METHODS

Between 2008 and 2017, we retrospectively reviewed the data of surgically resected clinically node-negative lung adenocarcinomas with a hypermetabolic activity. Furthermore, they were classified based on the presence of GGO. The prognostic significance of a GGO in hypermetabolic tumours was evaluated using the Cox proportional-hazards model. The overall survival (OS) was estimated by the Kaplan-Meier method using a log-rank test.

RESULTS

Of the 1134 surgically resected clinically node-negative lung adenocarcinoma, 603 cases with hypermetabolic activity (maximum standardized uptake value ≥3.0 mg/dl) were evaluated. Among them, there were 120 (20%) cases in the With GGO group and 483 (80%) in the Solid group. The 5-year OS of patients with hypermetabolic lung adenocarcinoma was significantly different between the With GGO and Solid groups (83.1% vs 59.4%, P < 0.001). After stratifying by the presence of GGO, maximum standardized uptake value and maximum tumour size were independently significant prognosticators in the Solid group by multivariable analysis; however, no clinical factors were associated with survival among the With GGO group. The 5-year OS was favourable despite the solid component size among the With GGO group (T1a + T1b: 85.5%, T1c: 80.0%, T2a or more: 84.2%, P = 0.904). For the Solid group, survival diminished drastically with increasing tumour size (T1a + T1b: 68.7%, T1c: 62.8%, T2a or more: 48.0%, P < 0.001).

CONCLUSIONS

The prognosis of lung adenocarcinoma with GGO was favourable even in hypermetabolic tumours. Accordingly, the presence of GGO should be considered as an important parameter in the next clinical T classification.

Frequent EGFR Mutations and Better Prognosis in Positron Emission Tomography-Negative, Solid-Type Lung Cancer

BACKGROUND

The differential diagnosis of a solitary solid-type lung nodule is diverse. 18F-fluorodeoxyglucose positron emission tomography (PET) has a high sensitivity in the diagnosis of solid-type lung cancers; however, PET-negative, solid-type lung cancers are rarely observed. In this study, we analyzed the clinical/genetic features and prognosis of PET-negative, solid-type lung cancers.

PATIENTS AND METHODS

Between January 2007 and February 2020, 709 patients with solid-type lung cancers (tumor size ≥2.0 cm) underwent pulmonary resection. Clinical, genetic, and prognostic features were evaluated in 27 patients (3.8%) with tumors showing negative PET results defined as SUVmax <2.0.

RESULTS

All 27 patients had lung adenocarcinoma; 23 had invasive adenocarcinomas and 4 had invasive mucinous adenocarcinomas. The PET-negative group showed high frequencies of females and never-smokers. Recurrence-free survival was significantly better in the PET-negative group compared with PET-positive counterparts extracted using propensity score matching from patients who underwent pulmonary resection during the same period (P = .0052). Furthermore, 83% of PET-negative, solid-type invasive lung adenocarcinoma patients harbored EGFR mutation, which was significantly higher than that of PET-positive, solid-type invasive lung adenocarcinoma patients (38%, n = 225) who received EGFR mutation testing in our cohort (P < .0001). PET-negative, solid-type lung adenocarcinoma patients with EGFR mutations had significantly better recurrence-free survival compared with PET-positive, solid-type lung adenocarcinoma patients with EGFR mutations extracted using propensity score matching (P = .0030).

CONCLUSION

PET-negative, solid-type lung cancers are characterized with a high incidence of EGFR mutation and a better prognosis compared with PET-positive, solid-type lung cancer.

Prognostic Impact of the Histologic Lepidic Component in Pathologic Stage IA Adenocarcinoma

INTRODUCTION

Because several articles have reported a prognostic association with the radiologic features of ground-glass opacity, we explored whether the histologic presence of a lepidic component had similar significance.

METHODS

We retrospectively evaluated 380 consecutive surgically resected lung adenocarcinomas (ADCs) of pathologic (p)stage IA. The tumors were classified into lepidic-positive and lepidic-negative ADCs. Clinicopathologic characteristics, radiographic ground-glass opacity status, and disease-free survival were compared between lepidic-positive and lepidic-negative ADCs and between part-solid and solid nodules on computed tomography images.

RESULTS

Of the 380 cases, 176 (46.3%) were lepidic-positive ADCs. Of the overall patients with pT1, lepidic-positive ADCs were found to have significantly better recurrence-free survival (5 y, 95.4% versus 87.0%, p = 0.005), but this significance was not reproduced in pT1 subcategories (pT1a, pT1b, and pT1c). Furthermore, the presence of the lepidic component was not an independent prognostic factor in the multivariate analysis (hazard ratio = 0.46 [95% confidence interval: 0.19-1.14], p = 0.09). We also analyzed the extent of the lepidic component with 10% incremental valuables. Although we found that a 10% or greater extent of lepidic component made the recurrence-free survival difference the largest, a clear prognostic impact was not obtained with this cutoff point.

CONCLUSIONS

Although lepidic-positive ADCs tended to have a favorable outcome, the lepidic component was not a clear independent prognostic factor in pstage I ADC.

Transbronchial lung parenchyma cryoablation with a novel flexible cryoprobe in an in vivo porcine model

PURPOSE

The purpose of this study was to evaluate the feasibility and safety of transbronchial cryoablation with a novel flexible cryoprobe using nitrogen as the refrigerant in an in vivo porcine model of lung parenchyma.

MATERIALS AND METHODS

A novel flexible cryoprobe using nitrogen as the refrigerant was used for transbronchial cryoablation of lung parenchyma in six normal female pigs. The cryoprobe was delivered to the distal bronchus in the bilateral porcine lungs via the bronchoscopic working channel under virtual bronchoscopy guidance. The position was confirmed with real-time computed tomography (CT). The whole procedure included two freeze-thaw cycles (15 min and 2 min, respectively). CT images were obtained during cryoablation and at 24 h, one week, two weeks and four weeks after the treatment to assess the effectiveness and safety of the procedure. Ablation zone tissue samples were obtained at 24 h and four weeks after the cryoablation for further histopathological analysis.

RESULTS

All ablation procedures (12/12; 100%) were performed successfully. No major complications occurred during the procedure or the observation period. The ablation zones were clearly depicted on CT with a maximal ablation zone volume at 24 h (21.88 ± 12.61 [SD] cm³) compared to 3.64 ± 2.06 (SD) cm³ and 10.73 ± 3.84 (SD) cm³ at the end of the 1st and 2nd freeze-thaw cycles, respectively (P < 0.001). Histopathological analysis revealed that a coagulative necrotic zone was formed along the target bronchus, with obvious vascular occlusion and hemorrhage 24 h after treatment. The lesions gradually formed fibrosis after four weeks.

CONCLUSION

The novel flexible bronchoscopy-guided cryoablation is a feasible, safe and effective modality in an in vivo porcine model of peripheral normal lung parenchyma, suggesting potential capabilities for the treatment of peripheral lung cancer in humans.

Prognostic influence of epidermal growth factor receptor mutation and radiological ground glass appearance in patients with early-stage lung adenocarcinoma

OBJECTIVES

The ADAURA demonstrated the efficacy of osimertinib as adjuvant therapy in patients with resected stage IB-IIIA adenocarcinoma harboring epidermal growth factor receptor (EGFR) mutations. However, it is controversial whether adjuvant therapy should be applied to all these patients because of their heterogeneities. This study aimed to examine the influence of GGO and EGFR mutations on the prognosis and to identify optimal targets for the development of perioperative therapy.

MATERIAL AND METHODS

Among the patients who underwent complete resection between 2003 and 2014 and had pathological stage IA3-IIA adenocarcinoma, 505 consecutive patients were examined for EGFR mutation status. The prognosis was analyzed among the clinicopathological factors including EGFR status and presence or absence of GGO.

RESULTS

Of the 489 patients, 193 (39.5%) showed EGFR mutations. The recurrence-free survival (RFS) and overall survival (OS) of the EGFR mutant were slightly better than those of the EGFR wild type. There was no difference in RFS and OS between EGFR mutant and wild type in patients with GGO; however, EGFR mutant showed better OS than EGFR wild type in patients without GGO. The presence of GGO was a strong independent prognostic predictor in OS and RFS, but EGFR mutations was not predictors. In patients without GGO, EGFR mutants showed slightly higher recurrence, especially with a hazard ratio of 1.427 in stage IB.

CONCLUSIONS

Adenocarcinoma with GGO show a very good prognosis, so may not require adjuvant therapy. It will be necessary to further develop perioperative therapy in patients with poor prognosis.

A clinicopathological study of lung adenocarcinomas with pure ground-glass opacity > 3 cm on high-resolution computed tomography

OBJECTIVES

This study aimed to discuss whether a diameter of 3 cm is a threshold for diagnosing lung adenocarcinomas presenting with radiological pure ground-glass mass (PGGM, pure ground-glass opacity > 3 cm) as adenocarcinomas in situ or minimally invasive adenocarcinomas (AIS-MIAs). Another aim was to identify CT features and patient prognosis that differentiate AIS-MIAs from invasive adenocarcinomas (IACs) in patients with PGGMs.

METHODS

From June 2007 to October 2015, 69 resected PGGMs with HRCT and followed up for ≥ 5 years were included in this study and divided into AIS-MIA (n = 13) and IAC (n = 56) groups. Firth's logistic regression model was performed to determine CT characteristics that helped distinguish IACs from AIS-MIAs. The discriminatory power of the significant predictors was tested with the area under the receiver operating characteristics curve (AUC). Disease recurrence was also evaluated.

RESULTS

Univariable and multivariable analyses identified that the mean CT attenuation (odds ratio: 1.054, p = 0.0087) was the sole significant predictor for preoperatively discriminating IACs from AIS-MIAs in patients with PGGMs. The CT attenuation had an excellent differentiating accuracy (AUC: 0.981), with the optimal cut-off value at -600 HU (sensitivity: 87.5%; specificity: 100%). Additionally, no recurrence was observed in patients manifesting with PGGMs > 3 cm, and the 5-year recurrence-free survival and overall survival rates were both 100%, even in cases of IAC.

CONCLUSIONS

This study demonstrated that PGGMs > 3 cm could still be AIS-MIAs. When PGGMs are encountered in clinical practice, the CT value may be the only valuable parameter to preoperatively distinguish IACs from AIS-MIAs.

KEY POINTS

• Patients with pure ground-glass opacity > 3 cm in diameter are rare but can be diagnosed as adenocarcinomas in situ or minimally invasive adenocarcinomas. • The mean CT attenuation is the sole significant CT parameter that differentiates invasive adenocarcinoma from adenocarcinoma in situ or minimally invasive adenocarcinoma in patients with pure ground-glass opacity > 3 cm. • Lung adenocarcinoma with pure ground-glass opacity > 3 cm has an excellent prognosis, even in cases of invasive adenocarcinoma.

The Prognostic Value of Preoperative Serum Tumor Markers in Non-Small Cell Lung Cancer Varies With Radiological Features and Histological Types

Objectives

To assess the association between common-used serum tumor markers and recurrence of lung adenocarcinoma and squamous cell carcinoma separately and determine the prognostic value of serum tumor markers in lung adenocarcinoma featured as ground glass opacities.

Methods

A total of 2,654 non-small cell lung cancer patients undergoing surgical resection between January 2008 and September 2014 were analyzed. The serum levels of carcinoma embryonic antigen (CEA), cytokeratin 19 fragment (CYFRA21-1), neuron-specific enolase (NSE), carbohydrate antigen 125 (CA125), carbohydrate antigen 153 (CA153) and carbohydrate antigen 199 (CA199) were tested preoperatively. Survival analyses were performed with COX proportional hazard regression.

Results

Among patients with lung adenocarcinoma, elevated preoperative serum CEA(HR=1.246, 95%CI:1.043-1.488, P=0.015), CYFRA21-1(HR=1.209, 95%CI:1.015-1.441, P=0.034) and CA125(HR=1.361, 95%CI:1.053-1.757, P=0.018) were significantly associated with poorer recurrence free survival (RFS). Elevated preoperative serum CA199 predicted worse RFS in patients diagnosed with lung squamous cell carcinoma (HR=1.833, 95%CI: 1.216-2.762, P=0.004). Preoperative serum CYFRA21-1(HR=1.256, 95%CI:1.044-1.512, P=0.016) and CA125(HR=1.373, 95%CI: 1.050-1.795, P=0.020) were independent prognostic factors for patients with adenocarcinoma presenting as solid nodules while serum CEA (HR=2.160,95%CI:1.311-3.558, P=0.003) and CA125(HR=2.475,95%CI:1.163-5.266, P=0.019) were independent prognostic factors for patients with adenocarcinoma featured as ground glass opacities.

Conclusions

The prognostic significances of preoperative serum tumor markers in non-small cell lung cancer were associated with radiological features and histological types.

Subsolid Lung Adenocarcinomas: Radiological, Clinical and Pathological Features and Outcomes

Lung adenocarcinomas manifesting as subsolid nodules usually have a favorable prognosis. This study aimed to have a comprehensive investigation of the radiological and clinicopathologic features and oncological outcomes of subsolid nodules. Between March 2010 and December 2015, 865 patients with surgically resected clinical IA subsolid lung adenocarcinoma were retrospectively reviewed. Patients were classified into the pure ground-glass nodules (GGN) (pGGN [n = 358], without solid component on lung and mediastinal windows), heterogeneous GGN (hGGN [n = 65], only with solid components on lung window), and real part-solid nodule (rPSN [n = 442], with solid component on both lung and mediastinal windows) groups. The clinicopathological features and survival time of the three groups were compared between groups. There was a significant increase in median tumor size (P < 0.001), solid component size measured at lung window (LW-SCS) (P < 0.001), and the proportion of invasive adenocarcinoma subtypes (P < 0.001) from pGGNs to hGGNs to rPSNs. After adjustment for LW-SCS, adenocarcinomas with predominant lepidic patterns were still more common in hGGNs than in rPSNs (P = 0.009). Patients with rPSNs had a significantly worse recurrence-free survival (RFS) than those with pGGNs and hGGNs (5-year: 91.9% versus 100% versus 100%, P < 0.001). Multivariate Cox analyses revealed that gender (both P < 0.05) and clinical T category (based on lung window [LW-cT] [P = 0.002] or mediastinal window [MW-cT] [P < 0.001]) were independent prognostic factors of RFS in the rPSN group. HGGNs represented as an intermediate subtype between pGGNs and rPSNs. Both pGGNs and hGGNs had excellent outcomes, while rPSNs exhibited a worse prognosis than them. Clinical T category and gender had prognostic implications for rPSNs.

Clinical Value and Pathologic Basis of Cystic Airspace Within Subsolid Nodules Confirmed as Lung Adenocarcinomas by Surgery

PURPOSE

To investigate the clinical value and pathologic basis of cystic airspace within lung adenocarcinomas manifesting as subsolid nodules.

PATIENTS AND METHODS

A retrospective study was conducted on a total of 541 surgically confirmed lung adenocarcinomas manifesting as subsolid nodules in computed tomography images, including 87 cases with cystic airspace and 454 cases without cystic airspace. The pathologic characteristics of the cases with and without cystic airspace were compared. The investigation of the pathologic structure of cystic airspace was attempted on the postoperative paraffin sections.

RESULTS

There was a significant difference in the containing of cystic airspace between preinvasive and invasive adenocarcinomas (10.5 vs 26.6%; P < .001). Multivariate analysis indicated that cystic airspace is an independent predictor of invasive adenocarcinomas (odds ratio, 3.220; 95% confidence interval, 1.822-5.687). Nodules containing multiple cystic airspaces are more likely to be invasive adenocarcinomas than nodules with a single cystic airspace (47.1 vs 72.2%; P < .05). On paraffin sections, the walls of the cystic airspace seemed to be mainly composed of atypical hyperplasia and/or tumor cells on the surface and the remaining smooth muscle cells and stroma below, which is similar to the structure of bronchi.

CONCLUSIONS

Cystic airspace may be a reliable predictor of invasive adenocarcinomas, the classification method based on the number of cystic airspaces might be suitable for the computed tomography-based typing of cystic airspace within subsolid nodules. Cystic airspace may derive from the destroyed and enlarged bronchi owing to the growth or infiltration of atypical hyperplasia and/or tumor cells.

Subsolid lesions exceeding 3 centimeters: the ground-glass opacity component still matters

BACKGROUND

Recent studies on the favorable prognosis of ground-glass opacities (GGO) featured lung adenocarcinoma compared with solid nodules were limited to small tumors measuring ≤3.0 cm. This study aimed to investigate whether GGO component could predict better prognosis in patients with large subsolid lesions exceeding 3cm compared with small solid nodules within the same clinical T category.

METHODS

From 2010 to 2015, a total of 1010 patients with completely resected clinical N0 lung adenocarcinoma were enrolled, including 860 solid lesions and 150 subsolid lesions exceeding 3cm. To analyze the prognostic significance of GGO component, propensity score matching adjusting solid component size was performed.

RESULTS

After propensity score matching, 144 pairs of patients were finally analyzed. The mean size of the solid component was 23.7mm in the GGO group and 24.4mm in the solid group(p=0.450). The GGO group had significantly better overall survival and recurrence-free survival (p=0.011 and p=0.003, respectively), which were also validated in patients with solid-predominant lesions. Subgroup analysis showed the GGO group was associated with better prognosis in each clinical T category.

CONCLUSIONS

The prognosis of patients with GGO lesions exceeding 3cm was better than that of patients with small solid lesions even within the same clinical T category. Clinical T classification incorporating GGO component may provide better prognostic prediction for patients with lung cancer exceeding 3cm.

Pathological features and prognostic implications of ground-glass opacity components on computed tomography for clinical stage I lung adenocarcinoma

PURPOSE

To investigate the prognostic implications and pathological features of clinical stage I lung adenocarcinoma with ground-glass opacity (GGO) on computed tomography (CT).

METHODS

The subjects of this retrospective study were 1228 patients with lung adenocarcinoma classified as clinical stage I, who underwent complete resection by lobectomy. The patients were divided into four groups based on the presence and proportion of GGO according to the consolidation-to-tumor ratio (CTR); A, CTR ≤ 0.5; B, 0.5 < CTR ≤ 0.75; C, 0.75 < CTR ≤ 1.0 with GGO; D, without GGO (pure-solid). We compared overall survival, pathological findings (N/ly/v/STAS), and histological subtypes within each clinical stage among the four groups.

RESULTS

We found no significant differences among tumors with GGO (groups A, B and C) for prognosis or pathological findings in all the clinical stages. The prognoses of groups A, B and C were significantly better than that of group D for patients with clinical stages IA2-IB disease. Tumors without GGO on CT had a significantly larger number of positive N, ly, v and STAS in almost all stages than tumors with GGO on CT. Tumors without GGO on CT had significantly more solid predominant and less lepidic predominant adenocarcinoma.

CONCLUSION

Not the proportion of GGO, but its presence on CT, as well as the size of the solid component, were correlated significantly with pathological characteristics and survival.

Extent of mediastinal nodal dissection in stage I non-small cell lung cancer with a radiological pure-solid appearance

BACKGROUND

Radiological pure-solid lung cancer denotes a high invasive nature compared to one that is part-solid. Mediastinal lymph nodal dissection (mLND) is a standard surgical procedure for nodal management in lung cancer surgery, however, the prognostic impact of the extent of mLND in pure-solid lung cancer is still unknown.

METHODS

We reviewed 459 patients with c-stage I radiological pure-solid lung cancer that underwent pulmonary lobectomy with mLND. Pure-solid was defined as a tumor showing only a consolidation without any ground glass opacity. The extent of mLND was classified into lobe-specific (L-mLND) and systematic (S-mLND). Prognostic significance of mLND was assessed by a multivariable analysis using propensity-score matching. Survivals were calculated by Kaplan-Meier methods using log-rank test.

RESULTS

Pathological nodal metastasis was found in 127 (27.6%) patients (hilar: 52 (11.3%), mediastinal: 75 (16.3%)). L-mLND was performed in 278 (61%) patients. A multivariable analysis did not show the survival difference for the extent of mLND (p = 0.266). The 5-year overall survival (OS) was not significantly different between S-mLND and L-mLND (74.3% vs. 72.7%, p = 0.712), which was similar even in 114 propensity-score matched pairs (78.8% vs. 79.9%, p = 0.665). While S-mLND showed a trend for survival benefit compared to L-mLND provided that the tumor showed higher standardized uptake value (SUVmax) (5y-OS: 70.0% vs. 59.2%, p = 0.093).

CONCLUSIONS

Prognostic impact of L-mLND was similar to S-mLND in c-stage I radiological pure-solid lung cancers in the propensity-score matched comparison. Among them, higher SUVmax value might be a promising indicator to decide the extent of mediastinal lymphadenectomy.

Predictive factors of recurrence after resection of subsolid clinical stage IA lung adenocarcinoma

BACKGROUND

Ongoing studies are currently investigating the extent of surgical resection required for subsolid cancers. This study aimed to investigate the predictive factors related to recurrence in patients with clinical stage IA subsolid cancer who underwent either lobectomy or sublobar resection.

METHODS

This was a prospective multicenter observational study conducted in eight qualifying university teaching hospitals between April 2014 and December 2016. A total of 173 patients with subsolid nodules pathologically confirmed to have primary lung adenocarcinoma and stage IA disease were included in the final analysis. All patients underwent lobectomy, segmentectomy, or wedge resection performed by experienced thoracoscopic surgeons at each site. The surgical procedure was chosen based on the decision of the surgeons involved. The primary endpoint was time to recurrence (TTR).

RESULTS

The study population was 43.9% (76 of 173) male with a mean age of 60.7 years. During the median follow-up period of 5.01 years, nine patients (5%) experienced disease recurrence. In the multivariable analysis, tumor size (size ≥2 cm) (hazard ratio: 73.717, 95% confidence interval [CI]: 3.635-895.036; p < 0.001) and stage IA3 (hazard ratio: 62.010, 95% CI: 2.837-855.185; p < 0.001) were independent predictors of tumor recurrence. When analyzing the recurrence outcome in patients according to surgical procedure, no significant difference was found in TTR among the three groups (i.e., lobectomy, segmentectomy, and wedge resection; p = 0.99).

CONCLUSIONS

Patients with radiologically subsolid lung adenocarcinoma measuring <3 cm could be candidates for sublobar resection instead of lobectomy.

Surgical Strategies for Pre- and Minimally Invasive Lung Adenocarcinoma 3.0: Lessons Learned From the Optimal Timing of Surgical Intervention

We discuss the optimal timing of surgery for lung cancer, and propose 3 surgical strategies for pre- and minimally invasive lung adenocarcinoma to avoid "overdiagnosis" and "overtreatment." Benign disease should not be treated as malignancy, pre- and minimally invasive disease should not be treated as invasive disease, and indolent malignancy should not be treated as aggressive malignancy.

Evaluation of solid portions in non-small cell lung cancer-the solid part is not always measurable for clinical T factor

BACKGROUND

Solid component size on thin-section computed tomography is used for T-staging according to the eighth edition of the Tumor Node Metastasis classification of lung cancer. However, the feasibility of using the solid component to measure clinical T-factor remains controversial.

METHODS

We evaluated the feasibility of measuring the solid component in 859 tumours, which were suspected cases of primary lung cancers, requiring surgical resection regardless of the procedure or clinical stage. After excluding 126 pure ground-glass opacity tumours and 450 solid tumours, 283 part-solid tumours were analysed to determine the frequency of cases where the measurement of the solid portion was difficult along with the associated cause. Pathological invasiveness was also evaluated.

RESULTS

The solid portion of 10 lesions in 283 part-solid nodules was difficult to measure due to an underlying lung disease (emphysema and pneumonitis). The solid portion of 62 lesions (21.9%) without emphysema and pneumonitis was difficult to measure due to imaging features of the tumours. Among the 62 patients, five had no malignancy and one with a tumour size of 33 mm had nodal metastasis. There were 56 lesions with a tumour size of ≤30 mm, wherein nodal metastases, vascular and/or lymphatic invasions were not observed.

CONCLUSION

For one-fifth of the part-solid tumours, measurement of the solid component was difficult. Moreover, these lesions had low invasiveness, especially in T1. The measurement of the solid portion and the classification of T1 in 1-cm increments may be complex.

Decoding the multicellular ecosystem of lung adenocarcinoma manifested as pulmonary subsolid nodules by single-cell RNA sequencing

Lung adenocarcinomas (LUAD) that radiologically display as subsolid nodules (SSNs) exhibit more indolent biological behavior than solid LUAD. The transcriptomic features and tumor microenvironment (TME) of SSN remain poorly understood. Here, we performed single-cell RNA sequencing analyses of 16 SSN samples, 6 adjacent normal lung tissues (nLung), and 9 primary LUAD with lymph node metastasis (mLUAD). Approximately 0.6 billion unique transcripts were obtained from 118,293 cells. We found that cytotoxic natural killer/T cells were dominant in the TME of SSN, and malignant cells in SSN undergo a strong metabolic reprogram and immune stress. In SSN, the subtype composition of endothelial cells was similar to that in mLUAD, while the subtype distribution of fibroblasts was more like that in nLung. Our study provides single-cell transcriptomic profiling of SSN and their TME. This resource provides deeper insight into the indolent nature of SSN and will be helpful in advancing lung cancer immunotherapy.

Clinical impact of a small component of ground-glass opacity in solid-dominant clinical stage IA non-small cell lung cancer

OBJECTIVE

Non-small cell lung cancers with a ground-glass opacity component have better prognosis than those with solid nodules of equivalent consolidation size. However, the impact of small ground-glass opacity components on prognosis is unknown. Therefore, we aimed to evaluate the significance of a small ground-glass opacity component in solid-dominant clinical stage IA non-small cell lung cancers.

METHODS

We reviewed the cases of 543 surgically resected solid-dominant c-stage IA non-small cell lung cancers, which was defined as a tumor with consolidation tumor ratio of 0.75 or more on computed tomography. The patients were classified into 2 groups: 0.75 or less consolidation tumor ratio less than 1 (n = 126) and consolidation tumor ratio of 1 (n = 417). The prognoses were compared between the 2 groups.

RESULTS

Among the 543 cases, multivariable analyses revealed that pure-solid appearance was a predictor of worse overall survival (hazard ratio, 2.051; 95% confidence interval, 1.044-4.028). Compared with the part-solid group, the pure-solid group was associated with poor survival in c-stages IA2 (5-year overall survival: 91.5% vs 76.8%, hazard ratio, 2.942; 95% confidence interval, 1.402-6.173; recurrence-free survival: 89.0% vs 68.8%, hazard ratio, 3.439; 95% confidence interval, 1.776-6.669) and IA3 (5-year overall survival: 93.5% vs 63.0%, hazard ratio, 5.110; 95% confidence interval, 1.607-16.241; recurrence-free survival: 80.5% vs 54.1%, hazard ratio, 2.789; 95% confidence interval, 1.290-6.027). The T categories significantly affected 5-year overall survival only in the pure-solid group (cT1a, 89.3%; cT1b, 76.8%; cT1c, 63.0%).

CONCLUSIONS

A small ground-glass opacity component has an impact on the prognosis of patients with solid-dominant c-stage IA non-small cell lung cancer. Therefore, c-stage IA non-small cell lung cancers should be evaluated separately for tumors with ground-glass opacity and pure-solid tumors.

Clinical features and prognosis of clinical N0 non-small cell lung cancer exceeding 30 mm

OBJECTIVES

This study aimed to determine the characteristics, ground glass opacity ratio and prognosis of patients with clinical N0 non-small cell lung cancer tumours exceeding 30 mm in size.

METHODS

Patients with clinical N0 non-small cell lung cancer and total tumour size >30 mm on preoperative computed tomography who underwent complete resection with lobectomy between January 2007 and December 2017 were included. The patients were divided into three groups: pure solid tumour, low ground glass opacity ratio (1-39%) tumour and high ground glass opacity ratio (≥40%) tumour. The cut-off line was determined based on the recurrence rate for every 10% ground glass opacity ratio.

RESULTS

Among the 227 study patients, 129 (56.8%) had a pure solid tumour, 54 (23.8%) had a low ground glass opacity ratio tumour and 44 (19.4%) had a high ground glass opacity ratio tumour. Three-year recurrence-free survival was significantly shorter in patients with a pure solid tumour (57.4%) than in patients with a low ground glass opacity ratio (74.5%; P = 0.009) or a high ground glass opacity ratio tumour (92.1%; P < 0.001). Multivariable analysis showed that ground glass opacity ratio was a significant independent prognostic factor for recurrence-free survival (hazard ratio, 0.175; P = 0.037).

CONCLUSION

Pure solid tumours comprised a large proportion of non-small cell lung cancer tumours >30 mm in size and their prognosis was poor. The presence of ground glass opacity and their relative proportion affect prognosis in patients with clinical N0 non-small cell lung cancer tumours >30 mm in size, similar to those with small-sized tumours.

Approach to the Subsolid Nodule

Most focal persistent ground glass nodules (GGNs) do not progress over 10 years. Research suggests that GGNs that do not progress, those that do, and solid lung cancers are fundamentally different diseases, although histologically they seem similar. Surveillance of GGNs to identify those that gradually progress is safe and does not risk losing a window. GGNs with 5 mm solid component or less than 10 mm consolidation (mediastinal and lung windows, respectively, on thin slice CT) are highly curable with resection. The optimal type of resection is unclear; sublobar resection is reasonable but an adequate margin is critically important.

Prognostic Significance of Ground-Glass Opacity Components in 5-Year Survivors With Resected Lung Adenocarcinoma

BACKGROUND

Reports on the prognosis for 5-year survivors with lung adenocarcinoma after resection are sparse. This study aimed to identify factors associated with overall survival (OS) and cancer-specific survival (CSS) for 5-year survivors with completely resected lung adenocarcinoma, and to determine whether preoperative imaging factors, including the presence of ground-glass opacity (GGO) components, affect late recurrence in long-term survivors.

METHODS

Complete resection of lung adenocarcinoma was performed for 1681 patients between January 2000 and December 2013. Of these patients, 936 who survived 5 years or longer after surgery were identified, and factors associated with OS and CSS were determined using the Cox proportional hazard model.

RESULTS

Multivariable analysis demonstrated that lymph node metastasis (p < 0.01) and absence of GGO components (p < 0.01) were independently associated with OS and CSS for the 5-year survivors. The absence of GGO components was significantly associated with OS (p < 0.01) and CSS (p < 0.01) also for the 5-year survivors with stage 1 disease (n = 782) and for the 5-year survivors without recurrence (n = 809). The incidence of recurrence anytime during the 10-year postoperative follow-up period differed significantly between the 5-year survivors with and without GGO components.

CONCLUSIONS

The absence of GGO components was significantly associated with an unfavorable prognosis for the 5-year survivors with completely resected lung adenocarcinoma regardless whether they had recurrences not.

Distinct clinicopathologic factors and prognosis based on the presence of ground-glass opacity components in patients with resected stage I non-small cell lung cancer

Background

This study was to investigate the prognostic value of ground-glass opacity(GGO) components and to evaluate distinct the clinicopathological variables of survival outcomes for the pure-GGO, part-solid and solid groups of patients with resected stage I non-small cell lung cancer (NSCLC).

Methods

We retrospectively reviewed the structured data for stage I NSCLC patients who had undergone the curative-intent surgical resection in the Lung Cancer Database of West China Hospital from 2009 to 2016. The eligible patients were divided into the pure-GGO, part-solid and solid groups according to the radiological manifestation. Univariate and multivariate Cox regression analyses were performed between the 3 groups. And we further evaluated the clinicopathological variables in each group separately.

Results

Among a total of 2,775 eligible patients enrolled into the cohort were 1,587 (57.19%) in the solid group, 508 (18.31%) in the part-solid group, and 680 (24.50%) in the pure-GGO group. The 5-year overall survival (OS) and recurrence-free survival (RFS) rates were 98.8% and 98.0% in the pure-GGO group, 96.0% and 86.5% in the part-solid group, and 88.0% and 75.5% in the solid group, respectively (P<0.001). Presence of GGO components was a significantly favorable prognosticator (HR =0.415, 95% CI: 0.286–0.601). Different groups had distinct prognostic factors. LVI was the shared risk factor for groups with presence of GGO components in both part-solid and pure-GGO groups. Pathological stage (IA or IB) was influential exclusively for the pure-GGO group. In the solid group, females, younger patients, and patients without VPI had better survival. But such independent significance did not exist in the other two groups.

Conclusions

GGO component was a strong prognosticator of better prognosis in resected patients with stage I NSCLC. Prognostic factors and survival outcomes were disparate among the pure-GGO, part-solid, and solid group. Our results support the proposal that the next edition tumor-node-metastasis (TNM) classification should consider the importance of GGO components as a new T descriptor.

8th Edition Tumor, Node, and Metastasis T-Stage Prognosis Discrepancies: Solid Component Diameter Predicts Prognosis Better than Invasive Component Diameter

The biggest change in the 8th edition of the tumor, lymph node, and metastasis (TNM) classification is the recommendation of the solid component diameter and invasive size for determining the clinical and pathological T-factor, respectively. Here, we validated new proposals for the Lung Cancer TNM classification’s revision and compared clinical and pathological T-stages. We retrospectively analyzed 177 cases of non-small cell lung cancers without lymph node metastasis, and involving complete resection, that occurred in our department between January 2017 and March 2019. We reviewed the overall tumor diameter, solid component diameter, and clinical T-factor on computed tomography (CT), and the pathological tumor diameter, pathological invasion diameter, pathological T-factor, and prognosis. The difference between the pathological invasive size and solid size on CT was within 5 mm in 99 cases (56%). At a two-year recurrence-free survival rate, the clinical T-stage demonstrated a better prognostic outcome than the pathological T-stage. Despite including the benign findings, the solid component diameter was better correlated with prognosis than the invasive size. Therefore, in cases of discrepancies of clinically and pathologically detected tumor size, the solid CT size should also be used for the pathological T classification.

Management of Ground-Glass Opacities in the Lung Cancer Spectrum

BACKGROUND

Along with the popularity of low-dose computed tomography lung cancer screening, an increasing number of lung ground-glass opacity (GGO) lesions are detected. This review focuses on lung adenocarcinoma manifesting as GGO.

METHODS

We performed a literature search of the PubMed/MEDLINE database to identify articles reporting GGO. The following terms were used: GGO, ground-glass opacity, GGN, ground-glass nodule, part-solid nodule, and subsolid nodule.

RESULTS

GGO is a nonspecific radiologic finding showing a hazy opacity without blocking underlying pulmonary vessels or bronchial structures. The pathology of GGO can be benign, preinvasive, or invasive adenocarcinoma. Although radiographic features may indicate malignancy, a short period of follow-up is the optimal method to distinguish between benign and malignant GGO lesions. Pathologically, not only lepidic, but also nonlepidic growth patterns can present as GGO. Lung adenocarcinoma with a GGO component is associated with excellent survival compared with solid lesions. Moreover, there are distinct prognostic factors in patients with lung adenocarcinoma manifesting as GGO or solid lesions. For selected GGO-featured lung adenocarcinoma, sublobar resection with selective or no mediastinal lymph node dissection may be sufficient. Intraoperative frozen section is an effective method to guide resection strategy. A less intensive postoperative surveillance strategy may be more appropriate given the excellent survival. Management of multiple GGO lesions requires comprehensive considerations of GGO characteristics and patient conditions.

CONCLUSIONS

Lung adenocarcinoma manifesting as GGO defines a special clinical subtype with excellent prognosis. The management of GGO-featured lung adenocarcinoma should be distinct from that of solid lesions.

Computed tomography density is not associated with pathological tumor invasion for pure ground-glass nodules

OBJECTIVE

Pure ground-glass nodules are considered to be radiologically noninvasive in lung adenocarcinoma. However, some pure ground-glass nodules are found to be invasive adenocarcinoma pathologically. This study aims to identify the computed tomography parameters distinguishing invasive adenocarcinoma from adenocarcinoma in situ and minimally invasive adenocarcinoma.

METHODS

From May 2011 to December 2015, patients with completely resected adenocarcinoma appearing as pure ground-glass nodules were reviewed. To evaluate the association between computed tomography features and the invasiveness of pure ground-glass nodules, logistic regression analyses were conducted.

RESULTS

Among 432 enrolled patients, 118 (27.3%) were classified as adenocarcinoma in situ, 213 (49.3%) were classified as minimally invasive adenocarcinoma, 101 (23.4%) were classified as invasive adenocarcinoma. There was no postoperative recurrence for patients with pure ground-glass nodules. Logistic regression analyses demonstrated that computed tomography size was the only independent radiographic factor associated with adenocarcinoma in situ (odds ratio, 47.165; 95% confidence interval, 19.279-115.390; P < .001), whereas computed tomography density was not (odds ratio, 1.002; 95% confidence interval, 0.999-1.005; P = .127). Further analyses revealed that there was no distributional difference in computed tomography density among 3 groups (P = .173). Even after propensity score matching for adenocarcinoma in situ/minimally invasive adenocarcinoma and invasive adenocarcinoma, no significant difference in computed tomography density was observed (P = .741). The subanalyses for pure ground-glass nodules with 1 cm or more in size also indicated similar results.

CONCLUSIONS

In patients with pure ground-glass nodules, computed tomography size was the only radiographic parameter associated with tumor invasion. Measuring computed tomography density provided no advantage in differentiating invasive adenocarcinoma from adenocarcinoma in situ and minimally invasive adenocarcinoma.

Preoperative CT-based Deep Learning Model for Predicting Disease-Free Survival in Patients with Lung Adenocarcinomas

Background Deep learning models have the potential for lung cancer prognostication, but model output as an independent prognostic factor must be validated with clinical risk factors. Purpose To develop and validate a preoperative CT-based deep learning model for predicting disease-free survival in patients with lung adenocarcinoma. Materials and Methods In this retrospective study, a deep learning model was trained to extract prognostic information from preoperative CT examinations. Data set 1 for training, tuning, and internal validation consisted of patients with T1-4N0M0 adenocarcinoma resected between 2009 and 2015. Data set 2 for external validation included patients with clinical T1-2aN0M0 (stage I) adenocarcinomas resected in 2014. Discrimination was assessed by using Harrell C index and benchmarked against the clinical T category. The Greenwood-Nam-D'Agostino test was used for model calibration. The multivariable-adjusted hazard ratios (HRs) were analyzed with clinical prognostic factors by using the Cox regression. Results Evaluated were 800 patients (median age, 64 years; interquartile range, 56-70 years; 450 women) in data set 1 and 108 patients (median age, 63 years; interquartile range, 57-71 years; 60 women) in data set 2. The C indexes were 0.74-0.80 in the internal validation and 0.71-0.78 in the external validation, both comparable with the clinical T category (0.78 in the internal validation and 0.74 in the external validation; all P > .05). The model exhibited good calibration in all data sets (P > .05). Multivariable Cox regression revealed that model outputs were independent prognostic factors (hazard ratio [HR] of the categorical output, 2.5 [95% confidence interval {CI}: 1.03, 5.9; P = .04] in the internal validation and 3.6 [95% CI: 1.6, 8.5; P = .003] in the external validation). Other than the deep learning model, only smoking status (HR, 3.4; 95% CI: 1.4, 8.5; P = .007) contributed further to prediction of disease-free survival for patients after resection of clinical stage I adenocarcinomas. Conclusion A deep learning model for chest CT predicted disease-free survival for patients undergoing an operation for clinical stage I lung adenocarcinoma. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Shaffer in this issue.

A modified T categorization for part-solid lesions in Chinese patients with clinical stage I Non-small cell lung cancer

OBJECTIVES

We evaluated the prognostic impact of the presence of ground glass opacity (GGO) component and compared a modified clinical T categorization (cT_m) with the current 8th classification (cT₈) for survival prediction in Chinese patients with clinical stage I non-small cell lung cancer (NSCLC).

METHODS

According to cT_m and cT₈ classifications, we retrospectively evaluated 1461 patients with part-solid or pure-solid lesions. The recurrence-free survival (RFS) and overall survival (OS) were analyzed by Kaplan-Meier method and Cox proportional hazard model. The concordance index (C- index), reclassification improvement (NRI), integrated discrimination improvement (IDI), and decision curve analysis (DCA) were performed to estimate reclassification net benefits of cT_m for survival prediction.

RESULTS

The cT₈ classification clearly stratifies the survival outcomes in solid tumors but not in part-solid tumors. The presence of GGO components was an independent prognostic factor for both RFS and OS (p < 0.001), indicating a better outcome in each clinical T stage. The C-index was significantly improved from 0.650 to 0.730 for RFS (p < 0.001) and 0.647 to 0.730 for OS (p < 0.001) after reclassifying by cT_m categorization. The DCA, NRI (RFS: 0.342, OS: 0.302), and IDI (RFS: 0.070, OS: 0.054) demonstrated that the cT_m classification provided more net benefit in the survival prediction compared with the current cT₈ classification.

CONCLUSIONS

The current cT₈ classification may not be appropriate for part-solid lesions because the presence of GGO components is associated with excellent prognosis despite clinical stage. Also, the cT_m classification for part-solid lesions showed an improvement in survival prediction.

Prognostic impact of a ground-glass opacity component in clinical stage IA non-small cell lung cancer

OBJECTIVE

We performed a validation study to confirm the prognostic importance of the presence of a ground-glass opacity component based on data of the Japan Clinical Oncology Group study, JCOG0201, which was a prospective observational study to predict the pathological noninvasiveness of clinical stage IA lung cancer in Japan.

METHODS

Among the 811 patients registered in JCOG0201, 671 were confirmed eligible by study monitoring and a central review of computed tomography. Registered c-stage IA lung cancer was less than 30 mm in maximum tumor size, which was classified into a with ground-glass opacity group (pure ground-glass opacity and part-solid tumor) or solid group based on the status of a ground-glass opacity component. T staging was reassigned in accordance with the 8th edition of the TNM staging system. To validate the prognostic impact, overall survival was estimated.

RESULTS

Of the cases, 432 (64%) were in the with ground-glass opacity group and 239 (36%) were in the solid group with a median follow-up time of 10.1 years. The 5-year overall survival was significantly different between the with ground-glass opacity group and solid group (95.1% vs 81.1%). The 5-year overall survival was excellent regardless of the solid component size in the with ground-glass opacity group (c-T1a or less: 97.2%, c-T1b: 93.4%, c-T1c: 91.7%). In contrast, prognostic impact of the tumor size was definitive in the solid group (c-T1a: 87.5%, c-T1b: 85.9%, c-T1c: 73.7%).

CONCLUSIONS

Favorable prognostic impact of the presence of a ground-glass opacity component was demonstrated in JCOG0201. The presence or absence of a ground-glass opacity should be considered as an important parameter in the next clinical T classification.

Numbers and Stations: Impact of Examined Lymph Node on Precise Staging and Survival of Radiologically Pure-Solid NSCLC: A Multi-Institutional Study

Objectives

To determine the optimal number of examined lymph nodes (ELNs) and examined node stations (ENSs) in patients with radiologically pure-solid NSCLC and to investigate the impact of ELNs and ENSs on accurate staging and long-term survival.

Methods

Data from six institutions in the People’s Republic of China on resected c-stage Ⅰ to Ⅱ NSCLCs presenting as pure-solid tumors were analyzed for the impact of ELNs and ENSs on nodal upstaging, stage migration, recurrence-free survival, and overall survival by using multivariate models. The correlations between different end points and ELNs or ENSs were fitted with a smoother (using Locally Weighted Scatterplot Smoothing tool), and the structural break points were determined by the Chow test.

Results

Both ELNs and ENSs were identified as prognostic factors for overall survival (ENS: hazard ratio [HR], 0.697; 95% confidence interval [CI]: 0.590–0.824; p < 0.001; ELN: HR, 0.945; 95% CI: 0.909–0.983; p = 0.005) and recurrence-free survival (ENS: HR, 0.863; 95% CI: 0.791–0.941; p = 0.001; ELN: HR, 0.960; 95% CI: 0.938–0.981; p < 0.001). Intraoperative ELNs and ENSs were found to be associated with postoperative nodal upstaging. Cut point analysis revealed an optimal cutoff of 16 LNs and five node stations for patients with c-stage Ⅰ to Ⅱ pure-solid NSCLCs, which were examined in our multi-institutional cohort.

Conclusions

Both ELNs and ENSs are associated with more accurate node staging and better long-term survival. We recommend 16 LNs and five stations as the cut point for evaluating the quality of LN examination for c-stage Ⅰ to Ⅱ patients with radiologically pure-solid NSCLCs.

Radiomics Signature Predicts the Recurrence-Free Survival in Stage I Non-Small Cell Lung Cancer

BACKGROUND

We aimed to explore the predictive value of radiomics signature for the recurrence-free survival (RFS) in patients with resected stage I non-small cell lung cancer.

METHODS

From January 2009 to December 2011, patients with resected stage I non-small cell lung cancer were divided into sub-solid and pure-solid groups according to presence of ground glass opacity in computed tomography. A total of 107 extracted radiomics features were reduced to 8 features by using LASSO Cox analysis to develop a radiomics signature for RFS prediction. Univariate and multivariate survival analyses were applied to identify independent prognostic variables, the Harrell concordance index (C-index) was measured to assess their prediction performance.

RESULTS

Our study included 378 patients with a median follow-up time of 63.2 months. The radiomics signature could stratify all patients into high-risk (180 of 378) and low-risk group (198 of 378) with different RFS (P < .001). In the sub-solid group (n = 115), 3 patients who occurred relapse were categorized into the high-risk group by the radiomics signature. In the pure-solid group, patients with low risk (141 of 263) had a better outcome than those with high risk (122 of 263) (P < .001). Multivariate analyses revealed that the histology (P < .001) and the developed radiomics signature (P < .001) remained independent prognostic factors for RFS.

CONCLUSIONS

Radiomics signature may be an independent imaging biomarker for predicting the survival, which may guide for personalizing treatment option in patients with stage I non-small cell lung cancer.

Validation of the Eighth Edition Clinical T Categorization System for Clinical Stage IA, Resected Lung Adenocarcinomas: Prognostic Implications of the Ground-Glass Opacity Component

INTRODUCTION

There is controversy regarding the clinical T (cT) category of lung adenocarcinomas that manifest as part-solid nodules (PSNs). We aimed to validate the cT category and to evaluate the independent prognostic role of the nodule type (i.e., part-solid versus solid).

METHODS

We retrospectively evaluated the prognostic value of clinico-radiologic factors regarding the overall survival of patients with clinical stage IA lung adenocarcinomas that were resected between 2008 and 2014. cT Category, nodule type, and their interaction term were included in the multivariable Cox regression analysis with other variables. In addition, a mixture cure model analysis was performed to investigate the association between the covariates and long-term survival.

RESULTS

A total of 744 patients (420 women; 362 PSNs; median age, 63 y) were included. The multivariable-adjusted hazard ratio (HR) of the nodule type was not significant (1.30, 95% confidence interval [CI]: 0.80-2.10, p = 0.291). However, the cT categories were significantly associated with overall survival (HR of cT1b, 2.33 [95% CI: 1.07-5.06, p = 0.033]; HR of cT1c, 5.74 [95% CI: 2.51-13.12, p < 0.001]). There were no interactions between the nodule type and the cT categories (all p > 0.05). The multivariable mixture cure model revealed that solid nodules were associated with a decreased probability of long-term survival (OR = 0.40, 95% CI: 0.18-0.92, p = 0.030). In addition, cT1c was a negative predictor of long-term survival (OR = 0.26, 95% CI: 0.07-0.94, p = 0.040).

CONCLUSIONS

The cT categorization system is valid for PSNs and solid nodules. Nevertheless, PSNs are a prognostic factor associated with long-term survival.

Flexible bronchoscopy-guided microwave ablation in peripheral porcine lung: a new minimally-invasive ablation

Background

Transbronchial lung biopsy is an important approach to diagnose peripheral lung cancer, but bronchoscopy based treatment options are limited and poorly studied. A flexible bronchoscopy-guided water-cooled microwave ablation (MWA) catheter was developed to evaluate the feasibility and safety both in ex vivo and in vivo porcine models.

Methods

Using direct penetration of the catheter through the surface of ex vivo porcine lung, ablations (n=9) were performed at 70, 80, 90 W for 10 minutes. Temperatures of the catheter and 10, 15, 20 mm away from the tip were measured. Under bronchoscopy conditions in porcine lung, ablations (n=18, 6 in ex vivo and 12 in vivo) were performed at 80 W for 5 minutes. Computed tomography (CT) was acquired perioperative, 24 hours, 2 weeks, and 4 weeks post ablation. Ablation zones were excised at 24 hours and 4 weeks respectively. Long-axis diameter (Dl) and short-axis diameter (Ds) were measured and tissues were sectioned for pathological examination.

Results

In-ex vivo lung, the temperature at 20 mm removed was over 60 °C at 80 W for 288±26 seconds. The ablations under bronchoscopic conditions were successful in-ex vivo and in vivo lung. No complications occurred during the procedures. Coagulation necrosis was visible at 24 hours, and repaired fibrous tissue was seen at 4 weeks.

Conclusions

The flexible bronchoscopy-guided water-cooled MWA is feasible and safe. This early animal data holds promise of MWA becoming a potential therapeutic tool for Peripheral Lung Cancers.

Prognostic Classification of Multiple Primary Lung Cancers Based on a Ground-Glass Opacity Component

BACKGROUND

We evaluated the prognostic impact of the presence of a ground-glass opacity (GGO) component on thin-section computed tomography for the refined clinical T classification of multiple primary lung cancers.

METHODS

We reviewed 272 surgically resected, clinically node-negative multiple lung cancers. Dominant tumors were classified into 2 groups based on the presence of a GGO component; that is, a GGO tumor (consolidation tumor ratio, 0 to <1.0) or pure-solid (PS) tumor (consolidation tumor ratio, 1.0). Furthermore, multifocal GGOs (MFGGOs) were defined as lesions showing a GGO component for all tumors. Their prognoses were evaluated using Cox proportional hazard model.

RESULTS

There were 153 MFGGOs (56%) with a significantly better 5-year overall survival than non-MFGGOs (97.2% vs 68.5%, P < .001). A multivariable analysis revealed that MFGGO and absence of nodal involvement were independently significant prognosticators of better survival (P = .007 and P = .012, respectively). Furthermore, among the patients of non-MFGGO groups, multivariate analysis showed that a PS + PS pattern and presence of nodal involvement were independently significant prognosticators of poorer survival (P = .008 and P = .001, respectively). We divided the tumors into 3 groups based on the results and focusing on the presence of a GGO; that is, MFGGO (n = 153), PS + additional GGO (n = 81), and PS + PS (n = 38). The 5-year overall survival was clearly split among them: MFGGO, 97.2%; PS + additional GGO, 82.1%; and PS + PS, 41.3% (P < .001).

CONCLUSIONS

Our results suggest that presence of a GGO component has the ability to distinguish the survival even for multiple lung cancers. Further investigations including multicenter trials are certainly warranted to address the revision of T variable of multiple lung cancers considering a presence of GGO component.

The probability of nodal metastasis in novel T-factor: the applicability of sublobar resection

Background

Recently sublobar resection is often indicated for small-sized peripheral lung cancer according to size or the consolidation/tumor ratio on CT; however, the T-factor classification drastically changed in the 8^th version. We investigated the relationship between a novel clinical T-factor classification, which includes other clinical information and the pathologic N-factor, to evaluate the applicability of the novel T-factor classification to sublobar resection.

Methods

From January 2013 to October 2017, 545 patients with cTis or cT1 lung cancer underwent surgery. Patients with non-peripheral type, induction treatment, cN≥1, cM1, and those without nodal dissection, preoperative evaluation by thin-sliced CT or FDG-PET were excluded. Finally, 325 patients were eligible for inclusion. All clinical parameters were prospectively collected and retrospectively analyzed. The 8^th edition of TNM classification was utilized.

Results

Nodal metastasis was detected in 38 (11.7%) patients. Among cTis/1mi/1a/1b/1c patients (n=10/11/51/146/107), pN1 and pN2 were observed in 0/0/2/9/10 and 0/0/1/8/8, respectively. cT1b/c patients showed a significantly higher rate of nodal metastasis (P=0.024). Among 253 cT1b/c patients, solid-type tumors (n=177) were more frequently associated with nodal metastasis. A ROC curve analysis revealed that SUVmax 1.9 was the cutoff value (AUC=0.827) for the presence of nodal metastasis. Using the 2 parameters of solid-type or SUVmax ≥1.9, we could successfully exclude patients with nodal metastasis, for whom sublobar resection is not indicated.

Conclusions

In terms of nodal metastasis, sublobar resection can be applicable for all cTis/1mi tumors; patients with cT1a/b/c tumors with mixed GGO and low SUVmax are candidates for sublobar resection.

Comparison of PD-L1 Expression Status between Pure-Solid Versus Part-Solid Lung Adenocarcinomas

Although lung adenocarcinomas (LADs) with ground-glass opacity (GGO; part-solid tumors) have been shown to differ from those without GGO (pure-solid tumors) in clinicopathological features and prognoses, whether programmed death ligand-1 (PD-L1) protein expression differs between these two tumor types is unclear. This study included 124 patients with clinical T1a-c LAD who received pulmonary resections during 2007-2009. The E1L3N antibody was used to stain for PD-L1 in primary LAD specimens. The specimens were considered PD-L1⁺ if ≥1% of tumor cells showed membrane staining, and were classified as having a high PD-L1⁺ tumor proportion score (TPS) if ≥50% of the tumor cells did so. Among the 124 patients, 45 had part-solid tumors and 79 had pure-solid tumors. These two groups did not significantly differ in terms of clinical factors. However, the rates for PD-L1 positivity (4% vs. 25%, p < 0.01) and high PD-L1⁺ TPS (2% vs. 16%, p = 0.02) were significantly higher in the pure-solid tumors. The multivariate analyses (logistic regression model) showed that the odds ratios for PD-L1 positivity and high PD-L1⁺ TPS in pure-solid LADs were 5.9 (95% CI; 1.2-29.7) and 8.0 (95% CI; 1.0-63.8), respectively. In conclusion, LADs with GGO were correlated with a lower incidence of PD-L1 expression than pure-solid tumors.

Distinct Prognostic Factors in Patients with Stage I Non-Small Cell Lung Cancer with Radiologic Part-Solid or Solid Lesions

INTRODUCTION

Recent studies have indicated that the presence of ground-glass opacity (GGO) components is associated with favorable survival. The purpose of this study was to reveal the prognostic value of GGO components and differences in prognostic factors for part-solid and solid lesions in invasive stage I NSCLC.

METHODS

The cases of 2010 patients with completely resected invasive pathological stage I NSCLC were reviewed according to the eighth edition of the TNM classification. Patients were categorized into the pure-GGO, part-solid, and solid groups based on consolidation-to-tumor ratio. Cox multivariate proportional hazard analyses were conducted to identify independent prognostic factors in each group.

RESULTS

Of the 2010 patients, 146 (7.3%) were in the pure-GGO group, 732 (36.4%) were in the part-solid group, and 1132 (56.3%) were in the solid group. Cox multivariate analyses revealed that GGO absence was a strong independent risk factor for worse recurrence-free survival (p < 0.001). For the pure-GGO group, there was no recurrence in spite of the invasive stage. For the part-solid group, visceral pleural invasion could not predict recurrence-free survival in general (p = 0.514) or in each tumor size group (for tumors size ≤1 cm, p = 0.664; for tumors size >1 to 2 cm, p = 0.456; for tumors size >2 to 3 cm, p = 0.900; and for tumors size >3 to 4 cm, p = 0.397). For the solid group, adenocarcinoma subtype was not a prognostic factor for recurrence-free survival in general (p = 0.162) or in each tumor size group (for tumors size ≤ 2 cm, p = 0.092; for tumors size >2 to 3 cm, p = 0.330; and for tumors size >3 to 4 cm, p = 0.885).

CONCLUSIONS

The presence of GGO components was a strong predictor in patients with invasive pathological stage I NSCLC. Risk factors were distinct in the part-solid and solid groups. There was no prognostic value of visceral pleural invasion in the part-solid group. Adenocarcinoma subtype did not have prognostic value in the solid group.

In situ growth in early lung adenocarcinoma may represent precursor growth or invasive clone outgrowth-a clinically relevant distinction

The switch from in situ to invasive tumor growth represents a crucial stage in the evolution of lung adenocarcinoma. However, the biological understanding of this shift is limited, and 'Noguchi Type C' tumors, being early lung adenocarcinomas with mixed in situ and invasive growth, represent those that are highly valuable in advancing our understanding of this process. All Noguchi Type C adenocarcinomas (n = 110) from the LATTICE-A cohort were reviewed and two patterns of in situ tumor growth were identified: those deemed likely to represent a true shift from precursor in situ to invasive disease ('Noguchi C1') and those in which the lepidic component appeared to represent outgrowth of the invasive tumor along existing airspaces ('Noguchi C2'). Overall Ki67 fraction was greater in C2 tumors and only C1 tumors showed significant increasing Ki67 from in situ to invasive disease. P53 positivity was acquired from in situ to invasive disease in C1 tumors but both components were positive in C2 tumors. Likewise, vimentin expression was increased from in situ to invasive tumor in C1 tumors only. Targeted next generation sequencing of 18 C1 tumors identified four mutations private to the invasive regions, including two in TP53, while 6 C2 tumors showed no private mutations. In the full LATTICe-A cohort, Ki67 fraction classified as either less than or greater than 10% within the in situ component of lung adenocarcinoma was identified as a strong predictor of patient outcome. This supports the proposition that tumors of all stages that have 'high grade' in situ components represent those with aggressive lepidic growth of the invasive clone. Overall these data support that the combined growth of Noguchi C tumors can represent two differing biological states and that 'Noguchi C1' tumors represent the genuine biological shift from in situ to invasive disease.