Prognostic significance of tumor spread through air spaces in patients with stage IA part-solid lung adenocarcinoma after sublobar resection

Clinical Importance of Grading Tumor Spread through Air Spaces in Early-Stage Small-Lung Adenocarcinoma

This study aimed to identify the clinical manifestation and implications according to the grading of tumor spread through air spaces in early-stage small (≤2 cm) pathological stage I non-mucinous lung adenocarcinomas. Medical records of patients with pathological stage I tumors sized ≤2 cm were retrospectively reviewed and analyzed. The furthest distance of the spread through air spaces from the tumor margin was measured on a standard-length scale (mm). Enrolled patients were categorized into spread through air spaces (STAS) (-) and STAS (+), and STAS (+) was subdivided according to its furthest distance as follows: STAS (+)-L (<2 mm) and STAS (+)-H (≥2 mm). Risk factors for STAS (+) included papillary predominant subtype (p = 0.027), presence of micropapillary patterns (p < 0.001), and EGFR (p = 0.039). The overall survival of the three groups did not differ significantly (p = 0.565). The recurrence-free survival of STAS (+)-H groups was significantly lower than those of STAS (-) and STAS (+)-L (p < 0.001 and p = 0.039, respectively). A number of alveolar spaces were definite risk factors for STAS (+)-H groups (p < 0.001), and male gender could be one (p = 0.054). In the patient group with small (≤2 cm) pathological stage I lung adenocarcinomas, the presence of STAS ≥ 2 mm was related to significantly lower recurrence-free survival. For identifying definite risk factors for the presence of farther STAS, more precise analysis from a larger study population should be undertaken.

What Is an Adequate Margin During Sublobar Resection of ≤3 cm N0 Subsolid Lung Adenocarcinomas?

BACKGROUND

Sublobar resection offers noninferior survival vs lobectomy for ≤2 cm non-small cell lung cancer and is commonly used for subsolid tumors. Although data exist for solid tumors, the minimum adequate margin of resection for subsolid adenocarcinomas remains unclear.

METHODS

This was a retrospective review of 1101 adenocarcinoma resections at our institution from 2006 to 2022. Inclusion criteria were tumors ≤3 cm with ≥10% radiographic ground glass, excised by sublobar resection. Exclusions were positive nodes or positive or unreported margin. The primary outcome was the rate of local recurrence (LR) at multiple thresholds of margin distance. The relationship between margin distance and solid component size was also explored.

RESULTS

Inclusion criteria were met by 194 patients. Median (interquartile range) tumor diameter and margin distance were 12 mm (9-17 mm) and 10 mm (5-17 mm), respectively. Median follow-up was 42.5 months. There was a progressive increase in LR with diminishing margin (0.1-cm decrements) from 1.5 cm to 0.5 cm. The difference in the rate of LR between "over" (n = 143) and "under" (n = 51) was most significant at 0.5 cm (8 of 51 [15.7%] vs 6 of 143 [4.2%]; P = .01) but did not reach α adjusted for multiple comparisons. On Cox regression for LR-free survival, margin ≤0.5 cm (P = .19) and solid component percentage (P = .14) trended to significance. Combining these using a ratio of margin distance-to-solid component size, a ratio of ≤1 showed a significantly higher rate of LR (7 [14.3%] vs 2 [2.0%], P = .009). Treatment of LRs provided at least intermediate-term survival in 87% of recurrences (median postrecurrence follow-up was 44 months).

CONCLUSIONS

During sublobar resection of subsolid lung adenocarcinomas, a margin distance-to-solid component size ratio of >1.0 appears to be a more reliable factor than margin distance alone to minimize local recurrence. Local recurrence, however, may not impact survival in patients with subsolid adenocarcinomas if timely treatment is administered.

Lung Cancer Surgery in Octogenarians: Implications and Advantages of Artificial Intelligence in the Preoperative Assessment

The general world population is aging and patients are often diagnosed with early-stage lung cancer at an advanced age. Several studies have shown that age is not itself a contraindication for lung cancer surgery, and therefore, more and more octogenarians with early-stage lung cancer are undergoing surgery with curative intent. However, octogenarians present some peculiarities that make surgical treatment more challenging, so an accurate preoperative selection is mandatory. In recent years, new artificial intelligence techniques have spread worldwide in the diagnosis, treatment, and therapy of lung cancer, with increasing clinical applications. However, there is still no evidence coming out from trials specifically designed to assess the potential of artificial intelligence in the preoperative evaluation of octogenarian patients. The aim of this narrative review is to investigate, through the analysis of the available international literature, the advantages and implications that these tools may have in the preoperative assessment of this particular category of frail patients. In fact, these tools could represent an important support in the decision-making process, especially in octogenarian patients in whom the diagnostic and therapeutic options are often questionable. However, these technologies are still developing, and a strict human-led process is mandatory.

Prognosis of spread through air spaces in invasive mucinous lung adenocarcinoma after curative surgery

INTRODUCTION

The purpose of this study is to investigate the prognostic impact of spread through air spaces (STAS) in invasive mucinous adenocarcinoma (IMA).

MATERIALS AND METHODS

From 2015 to 2019, patients who underwent complete resection of IMA were extracted from the prospective database. Multivariable Cox-regression analysis and inverse probability of treatment weight (IPTW) - adjusted log-rank test for 5-year recurrence-free survival (RFS) were performed.

RESULTS

STAS was observed in 39.1% (53 out of 133). The STAS (+) group shows larger tumor size (2.9 ± 2.4 cm vs 3.8 ± 2.4 cm, p = 0.031) and higher incidence of lympho-vascular invasion (6 [7.5%] vs 18 [34.0%], p < 00.001) compared to the STAS (-) group. The 5-year RFS was 66.1% in the STAS (+) group and 91.8% in the STAS (-) group (p < 00.001), and the incidence of locoregional recurrence was significantly higher in the STAS (+) group than the STAS (-) group (1 [1.2%] vs 12 [22.6%], p < 00.001). Multivariable analysis revealed that STAS was associated with poor prognosis for all-recurrence (hazard ratio 2.81, 95% confidence interval 1.01-7.81, p = 0.048). After IPTW adjustment, 5-year RFS was 66.3% in the STAS (+) group and 92.9% in the STAS (-) group (p = 0.007), and risk for locoregional recurrence was greater in the STAS (+) group than the STAS (-) group (1.1 [0.9%] vs 20.8 [16.6%], p < 00.001).

CONCLUSIONS

STAS showed negative prognostic impact on all-recurrence, especially due to locoregional recurrence, after curative resection of IMA.

Development and validation of a clinic-radiological model to predict tumor spread through air spaces in stage I lung adenocarcinoma

OBJECTIVES

Tumor spread through air spaces (STAS) is associated with poor prognosis and impacts surgical options. We aimed to develop a user-friendly model based on 2-[18F] FDG PET/CT to predict STAS in stage I lung adenocarcinoma (LAC).

MATERIALS AND METHODS

A total of 466 stage I LAC patients who underwent 2-[18F] FDG PET/CT examination and resection surgery were retrospectively enrolled. They were split into a training cohort (n = 232, 20.3% STAS-positive), a validation cohort (n = 122, 27.0% STAS-positive), and a test cohort (n = 112, 29.5% STAS-positive) according to chronological order. Some commonly used clinical data, visualized CT features, and SUVmax were analyzed to identify independent predictors of STAS. A prediction model was built using the independent predictors and validated using the three chronologically separated cohorts. Model performance was assessed using ROC curves and calculations of AUC.

RESULTS

The differences in age (P = 0.009), lesion density subtype (P < 0.001), spiculation sign (P < 0.001), bronchus truncation sign (P = 0.001), and SUVmax (P < 0.001) between the positive and negative groups were statistically significant. Age ≥ 56 years [OR(95%CI):3.310(1.150-9.530), P = 0.027], lesion density subtype (P = 0.004) and SUVmax ≥ 2.5 g/ml [OR(95%CI):3.268(1.021-1.356), P = 0.005] were the independent factors predicting STAS. Logistic regression was used to build the A-D-S (Age-Density-SUVmax) prediction model, and the AUCs were 0.808, 0.786 and 0.806 in the training, validation, and test cohorts, respectively.

CONCLUSIONS

STAS was more likely to occur in older patients, in solid lesions and higher SUVmax in stage I LAC. The PET/CT-based A-D-S prediction model is easy to use and has a high level of reliability in diagnosing.

Overexpression of VEGFA mediated by HIF-1 is associated with higher rate of spread through air spaces in resected lung adenocarcinomas

BACKGROUND

Spread through air spaces (STAS), a newly identified pattern of invasion in lung adenocarcinomas (LACs), is an unfavorable prognostic factor for patients with LAC, but the molecular characteristics and mechanisms underlying STAS have not been adequately explored.

METHODS

In total, 650 pathologically confirmed invasive LAC patients who underwent curative resection between December 2019 and April 2020 were reviewed. Disease-free survival (DFS) and overall survival (OS) were analyzed using the log-rank test and the Cox proportional hazards model. A comparative deep sequencing analysis was conducted to explore the molecular characteristics underlying STAS. Vascular endothelial growth factor A (VEGFA) expression was evaluated by immunoblotting and immunohistochemical analysis using fresh tumor tissue and tissue microarray.

RESULTS

STAS was more prevalent in patients with a smoking history (p < 0.001), high pathological TNM stage (p < 0.001), lymphovascular invasion (p < 0.001), visceral pleural invasion (p < 0.001) and micropapillary/solid histological subtypes (p < 0.001). STAS-negative patients had better DFS (p < 0.001) and OS (p = 0.003) compared to STAS-positive patients with invasive LACs, especially in the lymph node-negative population (p < 0.001). After RNA-sequencing analysis, hypoxia-inducible factor-1 (HIF-1) signaling was enriched and appeared to be strongly correlated with STAS, and more STAS-positive individuals were detected in the higher VEGFA-expressing group (p = 0.042).

CONCLUSIONS

We demonstrated that STAS was an independent prognostic marker of poor clinical outcome, especially in lymph node-negative patients, and that higher VEGFA expression mediated by HIF-1 signaling was associated with an increased STAS rate.

Comparison of lobectomy and sublobar resection for stage I non-small cell lung cancer: a meta-analysis based on randomized controlled trials

Background

This meta-analysis aimed to compare the prognostic between lobectomy and sublobar resection in patients with stage I non-small cell lung cancer (NSCLC).

Methods

We conducted a detailed search in PubMed, Embase, Web of Science, and the Cochrane Library for randomized controlled trials (RCTs) comparing the prognosis of lobectomy and sublobar resection for stage I NSCLC, with the primary outcomes being overall survival (OS) and disease-free survival (DFS).

Results

A total of 2222 patients were included in the 5 RCTs. The results showed no statistical difference in OS (HR=0.87, p=0.445) and DFS (HR=0.99, p=0.918) between patients who underwent lobectomy and sublobar resection during the total follow-up period. In terms of dichotomous variables, there were no statistical differences in OS (relative ratio [RR]=1.05, p=0.848) and DFS (RR=1.21, p=0.075) between the two groups during the total follow-up period, as well as 5-year OS (RR=0.96, p=0.409) and 5-year DFS (RR=0.95, p=0.270). In addition, subgroup analysis showed a better prognosis for non-adenocarcinoma patients with sublobar resection than lobectomy (HR=0.53, p=0.037), but also an increased cause of cancer death (not limited to lung cancer) (RR=1.56, p=0.004).

Conclusion

Our results showed that for stage I NSCLC, lobectomy is usually not a justified operation.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023407301, identifier CRD42023407301.

CT-based radiomics model to predict spread through air space in resectable lung cancer

BACKGROUND

Spread through air space (STAS) has been identified as a pathological pattern associated with lung cancer progression. Patients with STAS were related to a worse prognosis compared with patients without STAS. The objective of this study was to establish a radiomics model capable of forecasting STAS before surgery, which can assist surgeons in selecting the most appropriate operation type for patients with STAS.

METHOD

There were 537 eligible patients retrospectively included in this study. ROI segmentation was performed manually on all CT images to identify the region of interest. From each segmented lesion, a total of 1688 features were extracted. The tumor size, maximum tumor diameters, and tumor type were also recorded. Using Spearman's correlation coefficient to calculate the correlation and redundancy of elements, and redundant features less than 0.80 were removed. In order to reduce the level of overfitting and avoid statistical biases, a dimension reduction process of the dataset was conducted to decrease the number of features. Finally, a radiomics model included 44 features was established to predict STAS. To evaluate the performance of the model, the receiver operating characteristic (ROC) curve was used, and the area under the curve (AUC) was calculated, and the accuracy of the model was verified by 10-fold cross-validation.

RESULTS

The incidence of STAS was 38.2% (205/537). The tumor type, maximum tumor diameters, and consolidation tumor ratio were significantly different between STAS group and non-STAS group. The training group included 430 patients, while the test group was consisted with 107. The training group achieved an AUC of 0.825 (sensitivity, 0.875; specificity, 0.621; and accuracy, 0.749) and the test group had an AUC of 0.802 (sensitivity, 0.797; specificity,0.688; and accuracy, 0.748). The 10-fold cross-validation had an AUC of 0.834.

CONCLUSION

CT-based radiomic model can predict STAS effectively, which is of great importance to guide the selection of operation types before surgery.

The value of frozen section diagnosis of tumor spread through air spaces in small-sized (≤ 2 cm) non-small cell lung cancer

BACKGROUND

The current accuracy of frozen section diagnosis of tumor spread through air spaces (STAS) in non-small cell lung cancer (NSCLC) is poor. However, the accuracy and prognostic value of STAS assessment on frozen sections in small-sized NSCLC (diameter ≤ 2 cm) is unknown.

METHODS

Three hundred fifty-two patients with clinical stage I NSCLC (≤ 2 cm) were included, of which the paraffin sections and frozen sections were reviewed. The accuracy of STAS diagnosis in frozen sections was assessed using paraffin sections as the gold standard. The relationship between STAS on frozen sections and prognosis was assessed by the Kaplan-Meier method and log-rank tests.

RESULTS

STAS on frozen sections in 58 of 352 patients could not be evaluated. In the other 294 patients, 36.39% (107/294) was STAS-positive on paraffin sections and 29.59% (87/294) on frozen sections. The accuracy of frozen section diagnosis of STAS was 74.14% (218/294), sensitivity was 55.14% (59/107), specificity was 85.02% (159/187) and agreement was moderate (K = 0.418). In subgroup analysis, the Kappa values for frozen section diagnosis of STAS in the consolidation-to-tumor ratio (CTR) ≤ 0.5 group and CTR > 0.5 group were 0.368, 0.415, respectively. In survival analysis, STAS-positive frozen sections were associated with worse recurrence-free survival in the CTR > 0.5 group (P < 0.05).

CONCLUSIONS

The moderate accuracy and prognostic significance of frozen section diagnosis of STAS in clinical stage I NSCLC (≤ 2 cm in diameter; CTR > 0.5) suggests that frozen section assessment of STAS can be applied to the treatment strategy of small-sized NSCLC with CTR > 0.5.

Spread through air spaces is a powerful prognostic predictor in patients with completely resected pathological stage I lung adenocarcinoma

PURPOSE

To evaluate the frequency of spread through air spaces (STAS) in patients with early-stage primary lung cancer and to elucidate the association between STAS and various clinicopathological factors.

METHODS

We retrospectively reviewed data from a total of 265 consecutive patients who underwent lobectomy and mediastinal lymph node dissection (172 patients) or sublobar resection (93 patients) for completely resected pathological stage I lung adenocarcinoma. We evaluated clinical variables, including the preoperative serum carcinoembryonic antigen (CEA) level, tumour size, consolidation tumour ratio (CTR), maximum standardized uptake value (SUVmax) on FDG-PET, histological results, presence of STAS and vascular and lymphatic invasion.

RESULTS

The median follow-up time after surgery was 49 months. Eighty-seven patients (32.8 %) had STAS. The overall survival rates of patients in the STAS-positive and STAS-negative groups were 92.7 % and 97.1 % at 3 years, respectively (p = 0.1255), and the recurrence-free survival rates were 82.1 % and 95.9 % at 3 years, respectively (p = 0.0001). STAS was found in 73 patients (42.4 %) in the lobectomy group, which was a significantly higher proportion than the 14 patients (15.1 %) in the sublobar resection group. The STAS-positive group had significantly larger areas of invasion, higher CTRs, preoperative CEA and SUVmax levels, and more lymphatic and vascular invasion. STAS also correlated significantly with large consolidation sizes, larger invasive size, higher CTRs and the presence of a micropapillary pattern. Cox regression analysis after adjustment for important prognostic factors revealed that the presence of STAS was an independent predictor associated with postoperative recurrence, most of which was observed locoregionally.

CONCLUSIONS

STAS was an independent factor associated with postoperative recurrence after lung resection for stage I lung adenocarcinoma. Among stage IA patients, the postoperative outcomes of STAS-positive patients were worse than those of STAS-negative patients and were similar to those of stage IB patients.

Construction of Pulmonary Nodule CT Radiomics Random Forest Model Based on Artificial Intelligence Software for STAS Evaluation of Stage IA Lung Adenocarcinoma

Objective

Spread through air space (STAS) is an invasive characterization of lung adenocarcinoma and is regarded as a risk factor for poor prognosis. The aim of this study is to develop a random forest model for preoperative prediction of spread through air spaces (STAS) in stage IA lung adenocarcinoma.

Methods

92 patients with stage IA lung adenocarcinoma, who underwent computed tomography (CT) scan and surgical resection, were retrospectively reviewed. Each pulmonary nodule was automatically segmented by artificial intelligence (AI) software, and its CT-based radiomics were extracted. All patients were pathologically classified into STAS-negative and STAS-positive cohorts; then, clinical pathological and CT-based radiomics were compared between the two cohorts. Finally, a prediction model for evaluating STAS status in stage IA lung adenocarcinoma was established by a random forest model.

Results

Among 92 patients with stage IA lung adenocarcinoma, STAS positive was identified in 19 patients. The random forest classification model identified predictive features, including CT maximum value, consolidation to tumor ratio (CTR), 3D diameter, CT mean value, entropy, and CT minimum value. The misclassification rate of the random forest model is only 7.69%.

Conclusion

The risk factors of STAS in stage IA lung adenocarcinoma can be effectively identified based on the random forest model, and the hierarchical management of characteristic risk can be effectively realized. A random forest model for predicting STAS in IA lung adenocarcinoma is simple and practical.

Retrospective analysis of the prognostic implications of tumor spread through air spaces in lung adenocarcinoma patients treated with surgery

Background

Tumor spread through air spaces (STAS) in lung adenocarcinoma is a novel mechanism of invasion. STAS has been proposed as an independent predictor of poor prognosis. The aim of this study was to evaluate the correlations between STAS status and other clinicopathologic variables and to assess the prognostic implications of STAS and the distance from the edge of the tumor to the farthest STAS in patients with resected lung adenocarcinoma.

Material and methods

This is a single-institution retrospective observational study. We included all patients with resected lung adenocarcinoma from January 2017 to December 2018 at La Paz University Hospital. The cut-off for the distance from the edge of the tumor to the farthest STAS was 1.5 mm and was assessed by the area under the receiver operating characteristic curve.

Results

A total of 73 patients were included. STAS was found in 52 patients (71.2%). Histological grade 3 (P = 0.035) and absence of lepidic pattern (P = 0.022) were independently associated with the presence of STAS. The median recurrence-free survival (RFS) was 48.06 months [95% confidence interval (CI) 33.58 months to not reached]. STAS-positive patients had shorter median RFS [39.23 months (95% CI 29.34-49.12 months)] than STAS-negative patients (not reached) (P = 0.04). STAS-positive patients with a distance from the edge of the tumor to the farthest STAS ≥1.5 mm had an even shorter median RFS [37.63 months (95% CI 28.14-47.11 months)]. For every 1 mm increase in distance, the risk of mortality increased by 1.26 times (P = 0.04).

Conclusions

Histological grade 3 and absence of lepidic pattern were independently associated with the presence of STAS. STAS was associated with a higher risk of recurrence. The distance from the edge of the tumor to the farthest STAS also had an impact on overall survival.

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Lung adenocarcinoma patients with STAS had higher risk of recurrence.

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Patients with STAS and a distance from the edge of the tumor to the farthest STAS ≥1.5 mm had an even shorter RFS.

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The distance from the edge of the tumor to the farthest STAS also had an impact on overall survival.

[A Review on Pathological High-risk Factors and Postoperative Adjuvant Chemotherapy in Stage IA Lung Adenocarcinoma]

The survival rate needs to be improved in early stage non-small cell lung cancer patients. The risk of recurrence is relatively high in invasive adenocarcinoma patients with a solid or micropapillary component, lymphovascular invasion or tumor spread through air spaces. Systemic treatment options including radical surgical resection should be explored for this population. Adjuvant chemotherapy is not recommended for patients in stage IA in current guidelines. This article is a review on the research progress of the above pathological high-risk factors and the role of adjuvant chemotherapy in patients with pathological high-risk factors in stage IA lung adenocarcinoma.
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Adjuvant chemotherapy can benefit the survival of stage I lung adenocarcinoma patients with tumour spread through air spaces after resection: Propensity-score matched analysis

Background

It is still unclear whether stage I lung adenocarcinoma patients with tumour spread through air spaces (STAS) can benefit from postoperative adjuvant chemotherapy (ACT) after lobectomy. This study investigated the effect of ACT on the postoperative survival of patients with stage I (STAS⁺) lung adenocarcinoma.

Methods

We retrospectively analysed the clinical data of stage I (STAS⁺) invasive lung adenocarcinoma patients who underwent lobectomy in the Department of Thoracic Surgery of our hospital from January 1, 2013 to January 1, 2016. Propensity score matching (PSM) was performed to group patients to investigate whether ACT could lead to better prognosis of patients.

Results

A total of 593 patients with stage I (STAS⁺) lung adenocarcinoma were enrolled. The study after PSM included 406 patients. Kaplan–Meier survival analysis showed the experimental group had a better 3-year recurrence-free survival (RFS) rate (p = 0.037) and the 5-year RFS rate (p = 0.022) than the control group. It also had higher 5-year overall survival (p = 0.017). The multivariate analysis by Cox proportional hazard regression model showed that stage I STAS⁺ lung adenocarcinoma patients with lymphatic vessel invasion (HR: 1.711, 95% CI: 1.052-2.784; p = 0.045), vascular invasion (HR: 5.014, 95% CI: 3.154-7.969; p < 0.001), and visceral pleural invasion (HR: 2.086, 95% CI: 1.162-3.743; p = 0.014), and without ACT (HR: 1.675, 95% CI: 1.043-2.689; p = 0.033) had a significant survival disadvantage.

Conclusion

ACT can boost the postoperative survival of patients with stage I (STAS⁺) lung adenocarcinoma.

18F FDG-PET/CT analysis of spread through air spaces (STAS) in clinical stage I lung adenocarcinoma

OBJECTIVE

The purpose of this retrospective study was to investigate the utility of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F FDG-PET/CT) to predict spread through air spaces (STAS) in clinical stage I lung adenocarcinoma.

METHODS

Between April 2020 and January 2022, 52 patients (55 lesions) who underwent surgery for clinical stage I lung adenocarcinoma were enrolled. The lesions were divided into two groups according to the presence of STAS. 18F FDG-PET/CT parameters, specifically the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG), were calculated. The SUVmax, MTV, and TLG were compared between the two groups upon surgical pathological examination. Receiver operating characteristic (ROC) curve analysis was performed to identify a cut-off value.

RESULTS

Nineteen lesions (35%) were positive for STAS and 36 lesions were negative for STAS. According to the presence of STAS, significant differences were detected in the SUVmax (5.21 [range 1.52-16.50] vs. 2.42 [range 0.74-11.80], p = 0.0040) but not MTV (3.44 [range 0.65-24.36] vs. 2.95 [0.00-20.07], p = 0.20) and TLG (7.92 [range 0.93-47.82] vs. 5.63 [0.00-58.66], p = 0.14). SUVmax had an AUC value of 0.74 (95% CI 0.61-0.87) with a sensitivity of 89.5% and specificity of 52.8% at a cut-off of 2.48.

CONCLUSIONS

SUVmax rather than MTV and TLG were shown to be valuable indices for the prediction of STAS in clinical stage I lung adenocarcinoma.

A guide for managing patients with stage I NSCLC: deciding between lobectomy, segmentectomy, wedge, SBRT and ablation-part 2: systematic review of evidence regarding resection extent in generally healthy patients

Background

Clinical decision-making for patients with stage I lung cancer is complex. It involves multiple options (lobectomy, segmentectomy, wedge, stereotactic body radiotherapy, thermal ablation), weighing multiple outcomes (e.g., short-, intermediate-, long-term) and multiple aspects of each (e.g., magnitude of a difference, the degree of confidence in the evidence, and the applicability to the patient and setting at hand). A structure is needed to summarize the relevant evidence for an individual patient and to identify which outcomes have the greatest impact on the decision-making.

Methods

A PubMed systematic review from 2000-2021 of outcomes after lobectomy, segmentectomy and wedge resection in generally healthy patients is the focus of this paper. Evidence was abstracted from randomized trials and non-randomized comparisons with at least some adjustment for confounders. The analysis involved careful assessment, including characteristics of patients, settings, residual confounding etc. to expose degrees of uncertainty and applicability to individual patients. Evidence is summarized that provides an at-a-glance overall impression as well as the ability to delve into layers of details of the patients, settings and treatments involved.

Results

In healthy patients there is no short-term benefit to sublobar resection vs. lobectomy in randomized and non-randomized comparisons. A detriment in long-term outcomes is demonstrated by adjusted non-randomized comparisons, more marked for wedge than segmentectomy. Quality-of-life data is confounded by the use of video-assisted approaches; evidence suggests the approach has more impact than the resection extent. Differences in pulmonary function tests by resection extent are not clinically meaningful in healthy patients, especially for multi-segmentectomy vs. lobectomy. The margin distance is associated with the risk of recurrence.

Conclusions

A systematic, comprehensive summary of evidence regarding resection extent in healthy patients with attention to aspects of applicability, uncertainty and effect modifiers provides a foundation on which to build a framework for individualized clinical decision-making.

Clinicopathological Impact of the Spread through Air Space in Non-Small Cell Lung Cancer: A Meta-Analysis

This study aimed to elucidate the clinicopathological significance of spread through air space (STAS) in non-small cell lung cancer (NSCLC) through a meta-analysis. Using 47 eligible studies, we obtained the estimated rates of STAS in various histological subtypes of NSCLC and compared the clinicopathological characteristics and prognosis between NSCLC with and without STAS. The estimated STAS rate was 0.368 (95% confidence interval [CI], 0.336–0.0.401) in patients with NSCLC. Furthermore, the STAS rates for squamous cell carcinoma and adenocarcinoma were 0.338 (95% CI, 0.273–0.411) and 0.374 (95% CI, 0.340–0.409), respectively. Among the histological subtypes of adenocarcinoma, micropapillary-predominant tumors had the highest rate of STAS (0.719; 95% CI, 0.652–0.778). The STAS rates of solid- and papillary-predominant adenocarcinoma were 0.567 (95% CI, 0.478–0.652) and 0.446 (95% CI, 0.392–0.501), respectively. NSCLCs with STAS showed a higher visceral pleural, venous, and lymphatic invasion than those without STAS. In addition, anaplastic lymphoma kinase mutations and ROS1 rearrangements were significantly more frequent in NSCLCs with STAS than in those without STAS. The presence of STAS was significantly correlated with worse overall and recurrence-free survival (hazard ratio, 2.119; 95% CI, 1.811–2.480 and 2.372; 95% CI, 2.018–2.788, respectively). Taken together, the presence of STAS is useful in predicting the clinicopathological significance and prognosis of patients with NSCLC.

The prognostic significance of tumor spread through air space in stage I lung adenocarcinoma

Aim

There are still patients of stage I lung adenocarcinoma (ADC) suffering from local or distant recurrence. Herein we conducted a meta‐analysis to investigate the prognostic value of tumor spread through air space (STAS), a new form of invasion pattern, in patients with pathologically confirmed stage I lung ADC.

Methods

Related literature was searched using PubMed, Embase, Cochrane Library, and Web of Science databases from the inception dates to September 4, 2021. Recurrence‐free survival (RFS) and overall survival (OS) were set as primary outcome endpoints. In addition, subgroup analyses on operation mode, edition of the American Joint Committee on Cancer TNM staging, sample size, and research regions were also investigated.

Results

A total of 17 studies involving 9785 patients were included. The presence of STAS was detected in 31.2% of patients and was associated with poor RFS (adjusted hazard ratio [HR] = 1.93, p < 0.001) and OS (HR = 2.02, p < 0.001). In subgroup analysis on operation mode, the prognostic value of STAS was prominently shown in patients who underwent limited resection (RFS: HR = 3.58, p < 0.001; OS: HR = 3.37, p < 0.001), while for patients who underwent lobectomy, adverse impact of STAS on RFS was observed (HR = 1.60, p = 0.019), but no significant difference was observed on OS (HR = 1.56, p = 0.061). The results fluctuated in different regions while other factors did not alter the independent predictive value of STAS.

Conclusion

Tumor STAS should be considered as an adverse prognostic indicator for patients with stage I lung ADC, especially for those under limited resection. More intensive medical care for those patients needs to be investigated in further studies.

[Research Progress on Spread Through Air Spaces of Lung Cancer]

The concept of spread through air spaces (STAS) was first proposed in the World Health Organization (WHO) Classification of Tumors of the Lung, Pleura, Thymus and Heart (version 2015). STAS is defined as the micropapillary clusters, solid nests or single cells of tumor that exist in the air spaces of the surrounding lung parenchyma beyond the edge of the main tumor. Meanwhile, apart from the traditional invasion modes of lung adenocarcinoma (interstitial, visceral pleura and lym-phovascular invasion), STAS has been identified as the fourth invasion mode of lung adenocarcinoma. In recent years, the research on STAS has been a hot spot in the field of lung adenocarcinoma. The existence of STAS is related to lung cancer histopathology, gene mutation and other factors, and many studies have also confirmed that it can be used as an independent factor for tumor recurrence and prognosis. However, according to some studies, human factors can cause morphological artifacts of STAS, which still needs to be distinguished in clinical work. This paper reviews the research progress of STAS classification, related pathological features, genetic status changes, and human factors that may cause STAS artifacts.
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Prognostic implication of tumor spread through air spaces in patients with pathologic N0 lung adenocarcinoma

OBJECTIVES

Tumor spread through air spaces (STAS) has been identified as an invasive pattern in lung adenocarcinoma (ADC), but the prognostic implication of STAS has not been well studied in patients with pathologic N0 lung ADC. The purpose of this study was to evaluate the prognostic implication of STAS in pathologic N0 lung ADC patients after radical surgery.

MATERIALS AND METHODS

Between January 2017 and December 2018, 796 patients with completely resected pathologic N0 lung ADC were reviewed. Pearson's chi-square test or Fisher exact test was used for comparing the relationship between STAS and clinicopathological features. The log-rank test and multivariate Cox regression models were used to explore prognostic factors.

RESULTS

Among the 796 patients, STAS was positive in 201 patients (25.3%). The presence of STAS was significantly associated with patients with solid nodules (P < 0.001), micropapillary pattern-predominant adenocarcinoma/solid pattern-predominant adenocarcinoma (P < 0.001), larger tumor size (P < 0.001), visceral pleural invasion (P < 0.001) and lymphovascular invasion (P < 0.001). Multivariable analysis showed that STAS was an independent prognostic factor for recurrence-free survival (RFS) in pathologic N0 lung ADC patients (P = 0.014). For patients with acinar pattern-predominant adenocarcinoma (APA) / papillary pattern-predominant adenocarcinoma (PPA) / invasive mucinous adenocarcinoma (IMA) and patients who underwent lobectomy, STAS was an independent prognostic factor for RFS (P = 0.015, P = 0.011; respectively) and overall survival (OS) (P = 0.038, P = 0.020; respectively).

CONCLUSION

In this study, STAS was an independent prognostic factor for RFS in pathologic N0 lung adenocarcinomas, and it was also an independent prognostic factor for RFS and OS in patients with APA/PPA/IMA and those who received lobectomy.

Surgical Extent for Ground Glass Nodules

As diagnoses of small ground glass nodule (GGN)-type lung adenocarcinoma are increasing due to the increasing frequency of computed tomography (CT) screening, surgical treatment for GGN-type lung adenocarcinoma has rapidly become more common. However, the appropriate surgical extent for these lesions remains unclear; therefore, several retrospective studies have been published and prospectively randomized controlled trials are being undertaken. This article takes a closer look at each clinical study. Convincing evidence must be published on 2 issues for sublobar resection to be accepted as a standard surgical option for GGN lung adenocarcinoma. In the absence of such evidence, it is better to perform lobar resection as long as the patient has sufficient lung function. The first issue is the definition of a sufficient resection margin, and the second is whether lymph node metastasis is conclusively ruled out before surgery. An additional issue is the need for an accurate calculation of the total size and solid size on CT. Given the results of clinical studies so far, wedge resection or segmentectomy shows a good prognosis for GGNs with a total size of 2 cm or less. Therefore, sublobar resection will play a key role even in patients who can tolerate lobectomy.