Lung cancer with scattered consolidation: detection of new independent radiological category of peripheral lung cancer on thin-section computed tomography

Evaluation of Prognosis in Patients with Lung Adenocarcinoma with Atypical Solid Nodules on Thin-Section CT Images

Purpose To evaluate the clinicopathologic characteristics and prognosis of patients with clinical stage IA lung adenocarcinoma with atypical solid nodules (ASNs) on thin-section CT images. Materials and Methods Data from patients with clinical stage IA lung adenocarcinoma who underwent resection between January 2005 and December 2012 were retrospectively reviewed. According to their manifestations on thin-section CT images, nodules were classified as ASNs, subsolid nodules (SSNs), and typical solid nodules (TSNs). The clinicopathologic characteristics of the ASNs were investigated, and the differences across the three groups were analyzed. The Kaplan-Meier method and multivariable Cox analysis were used to evaluate survival differences among patients with ASNs, SSNs, and TSNs. Results Of the 254 patients (median age, 58 years [IQR, 53-66]; 152 women) evaluated, 49 had ASNs, 123 had SSNs, and 82 had TSNs. Compared with patients with SSNs, those with ASNs were more likely to have nonsmall adenocarcinoma (P < .001), advanced-stage adenocarcinoma (P = .004), nonlepidic growth adenocarcinoma (P < .001), and middle- or low-grade differentiation tumors (P < .001). Compared with patients with TSNs, those with ASNs were more likely to have no lymph node involvement (P = .009) and epidermal growth factor receptor mutation positivity (P = .018). Average disease-free survival in patients with ASNs was significantly longer than that in patients with TSNs (P < .001) but was not distinguishable from that in patients with SSNs (P = .051). Conclusion ASNs were associated with better clinical outcomes than TSNs in patients with clinical stage IA lung adenocarcinoma. Keywords: Adenocarcinoma, Atypical Solid Nodules, CT, Disease-free Survival, Lung, Prognosis, Pulmonary Supplemental material is available for this article. Published under a CC BY 4.0 license.

Prognostic impact of deep learning-based quantification in clinical stage 0-I lung adenocarcinoma

OBJECTIVES

To evaluate the performance of automatic deep learning (DL) algorithm for size, mass, and volume measurements in predicting prognosis of lung adenocarcinoma (LUAD) and compared with manual measurements.

METHODS

A total of 542 patients with clinical stage 0-I peripheral LUAD and with preoperative CT data of 1-mm slice thickness were included. Maximal solid size on axial image (MSSA) was evaluated by two chest radiologists. MSSA, volume of solid component (SV), and mass of solid component (SM) were evaluated by DL. Consolidation-to-tumor ratios (CTRs) were calculated. For ground glass nodules (GGNs), solid parts were extracted with different density level thresholds. The prognosis prediction efficacy of DL was compared with that of manual measurements. Multivariate Cox proportional hazards model was used to find independent risk factors.

RESULTS

The prognosis prediction efficacy of T-staging (TS) measured by radiologists was inferior to that of DL. For GGNs, MSSA-based CTR measured by radiologists (RMSSA%) could not stratify RFS and OS risk, whereas measured by DL using 0HU (2D-AIMSSA0HU%) could by using different cutoffs. SM and SV measured by DL using 0 HU (AISM0HU% and AISV0HU%) could effectively stratify the survival risk regardless of different cutoffs and were superior to 2D-AIMSSA0HU%. AISM0HU% and AISV0HU% were independent risk factors.

CONCLUSION

DL algorithm can replace human for more accurate T-staging of LUAD. For GGNs, 2D-AIMSSA0HU% could predict prognosis rather than RMSSA%. The prediction efficacy of AISM0HU% and AISV0HU% was more accurate than of 2D-AIMSSA0HU% and both were independent risk factors.

CLINICAL RELEVANCE STATEMENT

Deep learning algorithm could replace human for size measurements and could better stratify prognosis than manual measurements in patients with lung adenocarcinoma.

KEY POINTS

• Deep learning (DL) algorithm could replace human for size measurements and could better stratify prognosis than manual measurements in patients with lung adenocarcinoma (LUAD). • For GGNs, maximal solid size on axial image (MSSA)-based consolidation-to-tumor ratio (CTR) measured by DL using 0 HU could stratify survival risk than that measured by radiologists. • The prediction efficacy of mass- and volume-based CTRs measured by DL using 0 HU was more accurate than of MSSA-based CTR and both were independent risk factors.

A problem with clinical T factor in the 8th TNM edition: Prognosis and EGFR mutation status of small sized lung cancers with difficulty to measure the diameter of solid component in part-solid tumor

OBJECTIVE

Clinical T factors in the 8th TNM classification of lung cancer have a practical problem. In some cases, it is difficult to measure the size of the solid components in part-solid tumors, and the classification of these tumors is controversial.

METHODS

We evaluated 590 resected cT1N0M0 stage IA non-small-cell lung cancers based on the 7th edition between 2009 and 2012. Tumor and solid component diameters were measured using thin-section computed tomography (CT). We defined tumors with difficulty in measuring the size of the solid components as lung cancers with scattered or mixed consolidation (LCSMCs). LCSMCs were observed in 79 (13.4%) patients. Other tumors were classified as cTis, cT1mi, cT1a, cT1b, and cT1c, according to the 8th edition. We compared prognosis and epidermal growth factor receptor mutations (EGFRm) status of LCSMCs with those of cT1a, cT1b, and cT1c.

RESULTS

The difference in overall survival (OS) among cT1a, cT1b, and cT1c was significant (5-year-OS: 96.9% vs. 76.8% vs. 65.0%). There was no significant difference in prognosis between LCSCs and cT1a (5-year-OS: 92.4% vs. 96.9%). A significant difference was observed in the frequency of EGFRm between cT1a, cT1b, and cT1c (52.4%, 42.4%, and 29.8%). The incidence of EGFRm in LCSMCs was 54.8% and there was no significant difference between LCSMCs and cT1a.

CONCLUSIONS

The prognosis and frequency of EGFRm in LCSMCs were close to those in cT1a. As we cannot measure the diameter of the solid component in subsolid lung cancers, it may be appropriate to classify these tumors as cT1a tumors.

Prognostic impact of artificial intelligence-based volumetric quantification of the solid part of the tumor in clinical stage 0-I adenocarcinoma

INTRODUCTION

The size of the solid part of a tumor, as measured using thin-section computed tomography, can help predict disease prognosis in patients with early-stage lung cancer. Although three-dimensional volumetric analysis may be more useful than two-dimensional evaluation, measuring the solid part of some lesions is difficult using this methods. We developed an artificial intelligence-based analysis software that can distinguish the solid and non-solid parts (ground-grass opacity). This software calculates the solid part volume in a totally automated and reproducible manner. The predictive performance of the artificial intelligence software was evaluated in terms of survival or recurrence-free survival.

METHODS

We analyzed the high-resolution computed tomography images of the primary lesion in 772 consecutive patients with clinical stage 0-I adenocarcinoma. We performed automated measurement of the solid part volume using an artificial intelligence-based algorithm in collaboration with FUJIFILM Corporation. The solid part size, the solid part volume based on traditional three-dimensional volumetric analysis, and the solid part volume based on artificial intelligence were compared.

RESULTS

Higher areas under the curve related to the solid part volume were provided by the artificial intelligence-based method (0.752) than by the solid part size (0.722) and traditional three-dimensional volumetric analysis-based method (0.723). Multivariate analysis demonstrated that the solid part volume based on artificial intelligence was independently correlated with overall survival (P = 0.019) and recurrence-free survival (P < 0.001).

CONCLUSION

The solid part volume measured by artificial intelligence was superior to conventional methods in predicting the prognosis of clinical stage 0-I adenocarcinoma.

Efficacy of Adjuvant Chemotherapy With Tegafur-Uracil in Patients With Completely Resected, Node-Negative NSCLC-Real-World Data in the Era of Molecularly Targeted Agents and Immunotherapy

Introduction

In Japan, adjuvant tegafur-uracil (UFT) chemotherapy is recommended for patients with completely resected, stage I NSCLC. This treatment requires real-world re-evaluation because of recent advances in target-based and immuno-oncological treatments and refinement of lung cancer staging.

Methods

The Japan Clinical Oncology Group (JCOG) 0707, a phase 3 trial comparing the benefits of UFT and S-1 (tegafur-gimeracil-oteracil) in patients with completely resected stage I NSCLC (T1 >2 cm and T2 in the TNM sixth edition), was conducted in Japan. A multicenter observational cohort study (Comprehensive Support Project for Oncology Research [CSPOR]-LC03) was also conducted for those patients excluded from JCOG 0707 during the study enrollment period. Physicians from institutions that participated in JCOG 0707 retrospectively assessed the medical records of each patient. The efficacy of UFT was evaluated in the CSPOR-LC03 cohort.

Results

In the entire study population (n = 5005), patients treated with UFT (n = 1549) had significantly longer overall survival (OS) than those without any adjuvant chemotherapy (n = 3338). There was no significant difference in OS between the patients treated with UFT (n = 1061) and those without adjuvant chemotherapy (n = 1484) in the JCOG 0707-eligible population (logrank p = 0.755). For tumors without ground-glass attenuation and size greater than 3 cm, patients treated with UFT had significantly longer survival than those without adjuvant chemotherapy, on univariate but not on multivariate analysis.

Conclusions

There was no significant difference in OS between the patients treated with UFT and those without adjuvant chemotherapy in the clinical trial-eligible population. Adjuvant UFT for patients with completely resected NSCLC may be recommended only in patients with a tumor without ground-glass attenuation and size greater than 3 cm. In patients with node-negative early NSCLC, further study is needed to select patients who will benefit from adjuvant chemotherapy.

Presence of a Ground-glass Opacity Component is the True Prognostic Determinant in Clinical Stage I Non-Small Cell Lung Cancer

Introduction

Recent studies have suggested that including presence or absence of ground-glass opacity (GGO) may improve the tumor descriptor (T descriptor) classification in clinical stage I NSCLC. In this study, we analyzed prognostic implications of presence or absence of GGO, size of the solid component, and predominant histology to identify the true prognostic determinant for early-stage NSCLC.

Methods

We retrospectively examined 384 patients with clinical stage I NSCLC (solid: 242, part solid: 142) who underwent complete resection between 2009 and 2013.

Results

Survival curves of the whole cohort revealed good separation using the current TNM classification. Nevertheless, the part-solid group had a favorable prognosis irrespective of solid component size. Conversely, patients in the solid tumor group with tumors between 3 and 4 cm had a worse prognosis than patients whose tumors were less than or equal to 3 cm. Thus, we propose the following novel T descriptor classification: IA, part-solid tumors; IB, solid tumors less than or equal to 3 cm; and IC, solid tumors between 3 and 4 cm. This novel classification system stratified patient prognosis better than the current classification. On pathologic evaluation, the part-solid group always had better prognoses than the solid group in each subgroup divided by pathologic grade.

Conclusions

These results suggest that presence of GGO is the true prognostic determinant of stage I NSCLC, irrespective of the size of the solid component. Our novel T descriptor classification system could more accurately predict prognoses of clinical stage I NSCLC cases.

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.

The Application of Contrast Enhanced Ultrasound for Core Needle Biopsy of Subpleural Pulmonary Lesions: Retrospective Analysis in 92 Patients

The purpose of this study was to investigate the role of contrast-enhanced ultrasound (CEUS) in determining the viable target area in patients with subpleural pulmonary lesions before ultrasound-guided transthoracic core biopsy. In this retrospective study, we analyzed 92 patients with subpleural pulmonary lesions (63 males and 29 females; mean age: 65.17 ± 11.72 y). All patients underwent B-mode ultrasound, color Doppler and CEUS. Color Doppler was performed to identify the major vessels. The time to enhancement of the contrast agents, homogeneity of enhancement and the presence of areas without enhancement were recorded after administration of the contrast agents. The viable target areas were defined as regions showing enhancement relative to those without enhancement and regions showing delayed enhancement in reference to peripheral lung tissues showing early enhancement. Afterward, real-time ultrasound-guided transthoracic core needle (18 gauge) biopsies were performed and the complication rate, success rate and diagnostic accuracy were calculated. With CEUS, the needle pathways of these lesions were readjusted the biopsy strategy in 40/92 patients (43.5%). It was determined that the satisfactory rate of the subsequent biopsy specimen was 100%. The histologic diagnostic accuracy of the biopsy was 97.83%. No serious complications occurred during the biopsy. In conclusion, the application of CEUS before biopsy was able to depict the viable target areas of the lesion to readjust the biopsy routes. With the help of CEUS, ultrasound-guided core biopsy could obtain adequate samples, improve the diagnostic accuracy and reduce the complication rates of biopsies.

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.

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.

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.

New revisions and current issues in the eighth edition of the TNM classification for non-small cell lung cancer

In the eighth edition of the TNM classification of lung cancer, the prognostic impact of tumor size is emphasized as a descriptor of all T categories. Especially in lung cancer where tumor size is 5 cm or less, the 1-cm cutoff point significantly differentiated the survival outcome. In addition, the new staging categories were assigned, namely, Tis (adenocarcinoma in situ) and T1mi (minimally invasive adenocarcinoma). Furthermore, the measurement of a radiological solid component size excluding the ground glass opacity component or pathological invasive size without a lepidic component was proposed for deciding the cT/pT categories for lung adenocarcinoma. The N descriptors were kept the same as in the eventh edition on the whole, however, quantification of nodal disease had a prognostic impact based on the number of nodal stations involved in the eighth edition, i.e. N1a as a single N1 station, N1b as a multiple N1 station, N2a1 as a single N2 station without N1 (skip metastasis), N2a2 as a single N2 station with N1 disease, and N2b as a multiple N2 station. In the M descriptors, subclassification was performed based on the location or numbers of distantly metastatic lesions, i.e. M1a as any intrathoracic metastases, M1b as a single distant metastatic lesion in one organ, and M1c as multiple distant metastases in either a single organ or multiple organs. Survival analysis of the eighth edition of the TNM classification clearly separated the distinct groups, however, unsolved issues still remain that should be discussed and further revised for the forthcoming TNM staging system.

Controversies on lung cancers manifesting as part-solid nodules

PURPOSE

Summarise survival of patients with resected lung cancers manifesting as part-solid nodules (PSNs).

METHODS

PubMed/MEDLINE and EMBASE databases were searched for all studies/clinical trials on CT-detected lung cancer in English before 21 December 2015 to identify surgically resected lung cancers manifesting as PSNs. Outcome measures were lung cancer-specific survival (LCS), overall survival (OS), or disease-free survival (DFS). All PSNs were classified by the percentage of solid component to the entire nodule diameter into category PSNs <80% or category PSNs ≥80%.

RESULTS

Twenty studies reported on PSNs <80%: 7 reported DFS and 2 OS of 100%, 6 DFS 96.3-98.7%, and 11 OS 94.7-98.9% (median DFS 100% and OS 97.5%). Twenty-seven studies reported on PSNs ≥80%: 1 DFS and 2 OS of 100%, 19 DFS 48.0%-98.0% (median 82.6%), and 16 reported OS 43.0%-98.0% (median DFS 82.6%, OS 85.5%). Both DFS and OS were always higher for PSNs <80%.

CONCLUSION

A clear definition of the upper limit of solid component of a PSN is needed to avoid misclassification because cell-types and outcomes are different for PSN and solid nodules. The workup should be based on the size of the solid component.

KEY POINTS

• Lung cancers manifesting as PSNs are slow growing with high cure rates. • Upper limits of the solid component are important for correct interpretation. • Consensus definition is important for the management of PSNs. • Median disease-free-survival (DFS) increased with decreasing size of the nodule.

New simple radiological criteria proposed for multiple primary lung cancers

Background

Controversies remain as to the differential diagnosis between multiple primary lung cancer (MPLC) and intrapulmonary metastasis (IM) in lung cancers. We have investigated the clinical criteria for MPLC and here propose a set of new and simple criteria from the stand point of prognosis.

Methods

A retrospective study was conducted on 588 consecutive patients with resected lung cancer of clinical Stage IA between 2009 and 2012. Multiple lung cancers (MLCs) were observed in 103 (17.5%) of the 588 patients. All main and other tumors were divided into solid tumor (ST) and non-solid tumor (non-ST). We defined Group A as MLCs having at least one non-ST and Group B as all tumors being ST. Cox's proportional hazard model was used for the multivariate analyses to investigate the preoperative prognostic factors. We divided the MLCs into MPLC and IM based on the preoperative prognostic factors, and survival was estimated by the Kaplan-Meier method.

Results

A multivariate analysis with Cox's proportional hazards model revealed that Group A independently predicted good overall survival (HR = 0.165, 95% CI: 0.041-0.672).Differences in the 3- and 5-year overall survivals between Groups A and B were statistically significant (96.3%/92.2% vs. 70.0%/60.0%, Pvalue = 0.0002).

Conclusions

We suggest that Group A, defined as the presence of at least one tumor with a ground glass opacity component and clinical N0, should be excluded from the conventional concept of multiple lung cancers based on the criteria of Martini and Melamed as it has a very good prognosis. This group would be considered to be radiological MPLC.

What is the radiological definition of part-solid tumour in lung cancer?†

OBJECTIVES

The method of evaluating ground glass opacity (GGO) on thin-section computed tomographic (CT) scans is an issue of debate in early lung cancer. The term 'part-solid tumour' is frequently misused, and there is no consensus for its definition.

METHODS

A retrospective study was conducted on 775 consecutive patients with resected lung adenocarcinoma of clinical stage IA between 2008 and 2013. Part-solid tumours (PSTs) having a ground glass component and consolidation were divided into two categories using the radiological criterion of a consolidation-to-tumour (C/T) ratio of 0.5. Lung cancers were classified into four groups: (i) pure ground glass nodule (pGGN) (C/T ratio = 0); (ii) ground glass-predominant PST (GP-PST) (0< C/T ratio < 0.5); (iii) consolidation-predominant PST (CP-PST) (0.5 ≤ C/T ratio < 1) and (iv) solid tumour (ST) (C/T ratio = 1). We investigated the clinicopathological features and prognoses of patients with GP-PST and CP-PST.

RESULTS

The incidence of lymphatic invasion was 0% in pGGN, 0.8% in GP-PST, 16.8% in CP-PST and 46.2% in ST ( P  < 0.001). Among the PST lung cancers, predictors for lymphatic invasion were C/T ratio (OR 20.631, 2.755-154.508, P  = 0.003) and tumour size (OR 3.228, 1.413-7.375, P  = 0.005) in a multivariable analysis. The difference in recurrence-free survival between GP-PST and CP-PST was statistically significant [98.9 vs. 91.3% (5 years), P -value = 0.044].

CONCLUSIONS

PST comprised two categories in terms of invasiveness and prognosis based on the radiological criteria of a C/T ratio of 0.5. Ground glass-predominant PST and consolidation-predominant PST should be distinguished, and strategies specific to each determined using these terminologies.

Prognostic impact of a ground glass opacity component in the clinical T classification of non-small cell lung cancer

OBJECTIVE

To determine whether solid component size and the presence of a ground glass opacity (GGO) component are independently associated with survival outcomes in patients with early-stage non-small cell lung cancer (NSCLC) using the eighth edition Lung Cancer Stage Classification.

METHODS

We retrospectively evaluated 1029 surgically resected early-stage NSCLCs. T categories were assigned based on solid component size using the eighth classification. All tumors were classified into 1 of 2 groups: the GGO group or the solid group. We evaluated the prognostic impact of several clinicopathological variables in clinical T classification using a Cox proportional hazard model.

RESULTS

On multivariable analysis, the presence of a GGO component (hazard ratio [HR], 0.314; 95% confidence interval [CI], 0.181-0.529: P < .001) and solid component size (HR, 1.021; 95% CI, 1.006-1.036; P = .006) were identified as independently significant prognostic factors of overall survival. However, after accounting for the presence of a GGO component, neither maximum tumor size nor solid component size added to the prediction of long-term survival. Moreover, tumor size significantly affected survival outcome only in the solid group (HR, 1.020; 95% CI, 1.006-1.034; P = .004). Survival was excellent at ≥90% despite the revised T categories, provided that the tumor had a ground glass appearance. Meanwhile, tumor size significantly affected survival only in the solid group (P < .001).

CONCLUSIONS

The presence of a GGO component is a significant prognostic factor in early-stage NSCLC. External validation is required to assess whether it should be adopted as a novel factor in clinical T staging.

Whack-a-mole strategy for multifocal ground glass opacities of the lung

Ground glass opacity (GGO) is a good prognostic indicator for lung cancer and is useful for physicians to predict prognosis. Due to recent advances in computed tomography (CT), the chance to encounter GGO is rapidly increasing in clinical practice. Based on the studies on radiological pathological correlation, GGO represents pathological lepidic growth and consolidation on CT represents pathologically invasive components. Thus, consolidation tumor ratio 0.5 or less means pathological less invasiveness for lung cancer. Not a few studies have shown that sublobar resection is equivalent to lobectomy for radiological early lung cancers. Additionally, observation of GGO is one of the options for physicians. Indication of surgical intervention remains unclear. Physician observing GGO in practice should know the natural history of GGO to reach an optimal treatment decision. For multifocal GGO lesions clinical management is surely challenging. Whack-a-mole strategy, which means sublobar resection for radiological invasive cancer is one of the most promising strategies for such lesions.

Clinicopathological characteristics of lung cancer mimicking organizing pneumonia on computed tomography-a novel radiological entity of pulmonary malignancy

OBJECTIVE

Lung cancer could be misdiagnosed as benign due to its atypical radiological findings or difficulty in the histological diagnosis. We intended to elucidate the clinicopathological features of such lung cancers.

METHODS

Between 2008 and 2011, we performed surgical resection for 564 consecutive patients with lung adenocarcinoma. Findings on thin-section computed tomography were reviewed for all patients, 13 of whom were found to have lung cancer mimicking organizing pneumonia. The radiological and clinicopathological features of lung cancer mimicking organizing pneumonia and other adenocarcinomas were evaluated.

RESULTS

Among 13 patients with lung cancer mimicking organizing pneumonia, 4 were men. The median age was 70 years (range 62-81 years). Six patients were followed up for more than 1 year (range 1-108 months) as their lesions were misdiagnosed as organizing pneumonia. Preoperative carcinoembryonic antigen was significantly high (P = 0.025), and maximum tumor dimension was significantly large for lung cancer mimicking organizing pneumonia (30 vs. 23.6 mm, P = 0.001). Pathologically, there was no vascular invasion (P = 0.012) and only one lymphatic invasion (P = 0.064). One case of lymph node metastasis to the N2 node was found due to misdiagnosis as organizing pneumonia for 9 years.

CONCLUSIONS

Basically, lung cancer mimicking organizing pneumonia was less invasive and showed slow growth. However, nodal metastasis could be found. Thus, radiological diagnosis based on the findings of thin-section computed tomography is valuable to avoid delay in diagnosis.

Predictors of pathological non-invasive lung cancer with pure-solid appearance on computed tomography to identify possible candidates for sublobar resection

PURPOSE

This study aimed to establish favorable predictors for patients with clinical stage IA radiological pure-solid lung cancer to identify possible candidates for sublobar resection.

METHODS

We examined 275 patients with surgically resected clinical stage IA radiological pure-solid lung cancer. Pathological grade PL0, Ly0, V0, or N0 disease was defined as non-invasive pure-solid lung cancer (NIPS).

RESULTS

Nodal involvement was observed in 63 (23 %) patients with clinical stage IA pure-solid lung cancer, while NIPS was identified in 77 (28 %). Multivariate analysis revealed that air bronchogram (p = 0.0328), clinical T1a (p = 0.0041), and SUV_max (p = 0.0002) were significant clinical predictors of NIPS. When these clinical predictors were combined and the relevant patients' disease was classified as favorable, the frequency of nodal involvement was only 4 %. Furthermore, the 3-year overall survival (OS) of the patients with "favorable" clinical stage IA pure-solid lung cancer was 100 % despite their operative modes. In contrast, the 3-year OS even for patients with clinical stage IA disease, if they had neither of these clinical predictors, was 74.1 %.

CONCLUSIONS

Tumor size, the presence of air bronchogram, and the SUV_max level were significant favorable predictors of pathological non-invasive status, and patients with these clinical predictors could be candidates for sublobar resection for clinical stage IA pure-solid lung cancers.

Prediction of pathologic prognostic factors in patients with lung adenocarcinomas: comparison of thin-section computed tomography and positron emission tomography/computed tomography

Background

The ratio of the maximum diameter of consolidation to the maximum tumor diameter (C/T ratio) on thin-section computed tomography (TSCT) and the maximum standardized uptake value (SUVmax) on ¹⁸ F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) are often used as preoperative independent variables to evaluate the invasiveness of lung adenocarcinoma. We investigated the associations between these independent variables and pathologic invasiveness in pulmonary adenocarcinomas.

Methods

We selected patients with peripheral lung adenocarcinomas, definitively diagnosed by surgical resection, with diameters of ≤ 30 mm over a 4-year period ending in December 2010. The association between 3 independent variables (tumor size, SUVmax, and C/T ratio) and pathologic prognostic factors was evaluated using logistic analysis.

Results

We evaluated a total of 163 primary lung adenocarcinomas in 148 patients (93 males and 55 females; age range: 34 to 84 years). Using multivariate logistic regression analysis, SUVmax and the C/T ratio were significantly associated with tumor invasiveness (odds ratio [OR] = 1.227; p = 0.025 and OR = 1.019; p = 0.008, respectively). Tumor size was not associated with invasiveness (OR = 1.003; p = 0.925). For solid type adenocarcinomas, only SUVmax was significantly associated with invasiveness (OR = 1.558; p = 0.003). For subsolid type adenocarcinomas, only the C/T ratio was significantly associated with invasiveness (OR = 1.030; p = 0.009).

Conclusions

Both the C/T ratio and the SUVmax are significantly correlated with pathologic invasiveness in patients with small lung adenocarcinomas, while there was a difference between the 2 evaluations. Solid type adenocarcinomas with SUVmax values of ≥ 4.4 and subsolid type adenocarcinomas with C/T ratio ≥ 53% were so highly invasive.