Predictors of Death, Local Recurrence, and Distant Metastasis in Completely Resected Pathological Stage-I Non–Small-Cell Lung Cancer

High-risk features associated with recurrence in stage I lung adenocarcinoma

OBJECTIVE

There is a lack of knowledge regarding the use of prognostic features in stage I lung adenocarcinoma (LUAD). Thus, we investigated clinicopathologic features associated with recurrence after complete resection for stage I LUAD.

METHODS

We performed a retrospective analysis of patients with pathologic stage I LUAD who underwent R0 resection from 2010 to 2020. Exclusion criteria included history of lung cancer, induction or adjuvant therapy, noninvasive or mucinous LUAD, and death within 90 days of surgery. Fine and Gray competing-risk regression assessed associations between clinicopathologic features and disease recurrence.

RESULTS

In total, 1912 patients met inclusion criteria. Most patients (1565 [82%]) had stage IA LUAD, and 250 developed recurrence: 141 (56%) distant and 109 (44%) locoregional only. The 5-year cumulative incidence of recurrence was 12% (95% CI, 11%-14%). Higher maximum standardized uptake value of the primary tumor (hazard ratio [HR], 1.04), sublobar resection (HR, 2.04), higher International Association for the Study of Lung Cancer grade (HR, 5.32 [grade 2]; HR, 7.93 [grade 3]), lymphovascular invasion (HR, 1.70), visceral pleural invasion (HR, 1.54), and tumor size (HR, 1.30) were independently associated with a hazard of recurrence. Tumors with 3 to 4 high-risk features had a higher cumulative incidence of recurrence at 5 years than tumors without these features (30% vs 4%; P < .001).

CONCLUSIONS

Recurrence after resection for stage I LUAD remains an issue for select patients. Commonly reported clinicopathologic features can be used to define patients at high risk of recurrence and should be considered when assessing the prognosis of patients with stage I disease.

Pretreatment quality of life and survival in patients with lung cancer: a systematic review and meta-analysis

BACKGROUND

Although many studies have explored the correlation between quality of life and survival, none have reported this relationship for specific cancers assessed at distinct time points. This meta-analysis aimed to investigate the impact of pretreatment Global Quality of Life (QOL) and functioning QOL, including physical, social, role, emotional, and cognitive QOLs, on mortality risk in patients with lung cancer.

METHODS

A literature search was conducted across the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, and PubMed databases for articles published between their inception and December 2022. Subsequently, 11 studies were selected based on predefined eligibility criteria to investigate the relationship between pretreatment QOLs and mortality risk in patients with lung cancer.

RESULTS

Pretreatment global, physical, social, role, and emotional QOLs were significantly associated with mortality risk as follows: Global QOL (hazard ratio [HR] = 1.08 95% confidence interval [CI] = 1.03-1.13); Physical QOL (HR = 1.04 95% CI = 1.02-1.05); Social QOL (HR = 1.02 95% CI = 1.01-1.03; Role QOL (HR = 1.01 95% CI = 1.01-1.02); Emotional QOL (HR = 1.01 95% CI = 1.00-1.03).

CONCLUSIONS

These findings underscore the importance of early QOL assessment after diagnosis as well as early provision of physical, social, and psychological support accommodating each patient's demands.

TRIAL REGISTRATION

The International Prospective Register of Systematic Reviews registration number CRD42023398206, Registered on February 20, 2023.

Harnessing natural product polysaccharides against lung cancer and revisit its novel mechanism

The incidence and mortality of lung cancer are on the rise worldwide. However, the benefit of clinical treatment in lung cancer is limited. Owning to important sources of drug development, natural products have received constant attention around the world. Main ingredient polysaccharides in natural products have been found to have various activities in pharmacological research. In recent years, more and more scientists are looking for the effects and mechanisms of different natural product polysaccharides on lung cancer. In this review, we focus on the following aspects: First, natural product polysaccharides have been discovered to directly suppress the growth of lung cancer cells, which can be effective in limiting tumor progression. Additionally, polysaccharides have been considered to enhance immune function, which can play a pivotal role in fighting lung cancer. Lastly, polysaccharides can improve the efficacy of drugs in lung cancer treatment by regulating the gut microbiota. Overall, the research of natural product polysaccharides in the treatment of lung cancer is a promising area that has the potential to lead to new clinical treatments. With better understanding, natural product polysaccharides have the potential to become important components of future lung cancer treatments.

CD44v6 downregulation as a prognostic factor for distant recurrence in resected stage I lung adenocarcinomas

CD44 and CD44 variant isoforms have been reported as contributing factors to cancer progression. In this study, we aimed to assess whether CD44 and its variant isoforms were correlated with the prognostic factors for distant metastasis in stage I lung adenocarcinomas using tissue microarray and immunohistochemistry. In this single-center retrospective study, we analyzed the data of 490 patients with stage I lung adenocarcinoma resected between 1999 and 2016. We constructed tissue microarrays and performed immunohistochemistry for CD44s, CD44v6, and CD44v9. The risk of disease recurrence and its associations with clinicopathological risk factors were assessed. CD44v6 expression was significantly associated with recurrence. Patients with CD44v6-negative tumors had a significantly increased risk of developing distant recurrence than patients with CD44v6-positive tumors (5-year cumulative incidence of recurrence (CIR), 10.7% vs. 4.6%; P = 0.009). However, CD44v6-negative tumors were not associated with an increased risk of locoregional recurrence compared to CD44v6-positive tumors (5-year CIR, 6.0% vs. 4.0%; P = 0.39). The overall survival (OS) of patients with CD44v6-negative tumors was significantly lower than that of patients with CD44v6-positive tumors (5-year OS: 87% vs. 94%, P = 0.016). CD44v6-negative tumors were also associated with invasive tumor size and lymphovascular invasion. Even in stage I disease, tumors with negative-CD44v6 expression had more distant recurrences than those with positive-CD44v6 expression and were associated with poor prognosis in resected stage I lung adenocarcinomas. Thus, CD44v6 downregulation may be a prognostic factor for distant metastasis in stage I lung adenocarcinomas.

Recurrence After Complete Resection for Non-Small Cell Lung Cancer in the National Lung Screening Trial

BACKGROUND

The objective of this study was to evaluate patterns, predictors, and long-term outcomes of recurrent disease after complete resection for early-stage non-small cell lung cancer (NSCLC) using the National Lung Screening Trial (NLST).

METHODS

The frequency of recurrence in patients with pathologic stage I-II NSCLC who underwent complete resection (lobectomy or bilobectomy) in the NLST was evaluated. Predictors of increased risk of recurrence were assessed by Fine-Gray competing risks regression.

RESULTS

Of the 497 patients meeting study inclusion criteria, 94 experienced a recurrence-a rate of 4.9 (95% CI, 4.0-6.0) per 100 person-years. The 5-year cumulative incidence of recurrence was 20.1% (95% CI, 16.5%-23.9%). Most patients experienced recurrences at distant sites alone (n = 47 [50.0%]) or at both locoregional and distant sites (n = 30 [31.9%]). The median time from resection to recurrence was 18.8 (10.6-30.7) months. The incidence rate of recurrence was significantly lower among patients with lung cancer detected by low-dose computed tomography screening during one of the three screening rounds of the NLST when compared with patients with lung cancer detected by chest radiography screening and patients with lung cancer not detected by any form of screening (ie, those diagnosed after a negative or missed screening exam and those diagnosed during follow-up after the three screening rounds of the NLST were completed) (P < .001). Median survival (from the date of recurrence) of patients with pathologic stage I and stage II disease who had recurrences at locoregional, distant, or both sites was 63.0, 23.1, and 9.8 months and 28.9, 8.7, and 10.2 months, respectively.

CONCLUSIONS

In this analysis of NLST participants with completely resected stage I-II NSCLC, the 5-year cumulative incidence of recurrence was 20%. Nearly 82% of recurrences were at distant sites and associated with poor survival.

Clinical Outcome of Stereotactic Body Radiotherapy in Patients with Early-Stage Lung Cancer with Ground-Glass Opacity Predominant Lesions: A Single Institution Experience

PURPOSE

The detection rate of early-stage lung cancer with ground-glass opacity (GGO) has increased, and stereotactic body radiotherapy (SBRT) has been suggested as an alternative to surgery in inoperable patients. However, reports on treatment results are limited. Therefore, we performed a retrospective study to investigate the clinical outcome after SBRT in patients with early-stage lung cancer with GGO-predominant tumor lesions at a single institution.

MATERIALS AND METHODS

This study included 89 patients with 99 lesions who were treated with SBRT for lung cancer with GGO-predominant lesions that had a consolidation-to-tumor ratio of ≤0.5 at Asan Medical Center between July 2016 and July 2021. A median total dose of 56.0 Gy (range, 48.0-60.0) was delivered using 10.0-15.0 Gy per fraction.

RESULTS

The overall follow-up period for the study was median 33.0 months (range, 9.9 to 65.9 months). There was 100% local control with no recurrences in any of the 99 treated lesions. Three patients had regional recurrences outside of the radiation field, and three had distant metastasis. The 1-year, 3-year, and 5-year overall survival rates were 100.0%, 91.6%, and 82.8%, respectively. Univariate analysis revealed that advanced age and a low level of diffusing capacity of the lungs for carbon monoxide were significantly associated with overall survival. There were no patients with grade ≥3 toxicity.

CONCLUSION

SBRT is a safe and effective treatment for patients with GGO-predominant lung cancer lesions and is likely to be considered as an alternative to surgery.

Impact of the Number of Harvested Lymph Nodes on Long-Term Survival in Node-Negative Non-Small-Cell Lung Cancer: Based on Clinical Stage But Not Pathological Stage

BACKGROUND

We aimed to investigate the impact of the number of harvested lymph nodes (LNs) on the overall survival (OS) and disease-free survival (DFS) of patients with clinical node-negative (cN0) non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

A total of 2247 patients with cN0 NSCLC between 2001 and 2014 were included. Scatter plots of hazard ratios from Cox proportional hazards models against the number of harvested LNs were created, and curves were fitted using a LOWESS smoother. Chow test was used to determine the cut-off points for the optimal number of harvested LNs. Long-term survival was compared between groups divided by the cut-off points.

RESULTS

The increasing numbers of harvested LNs and N2 level LNs were independent factors favoring OS and DFS. Seventeen LNs and 10 N2 level LNs were determined as the optimal cut-off points. The patients with ≥17 harvested LNs had a better OS (P = .001) and DFS (P = .002), while the patients with ≥10 harvested N2 level LNs also had a better OS (P < .001) and DFS (P = .001). The increasing numbers of harvested LNs and N2 level LNs were independent prognostic factors associated with prolonged OS and DFS only in patients with clinical T2 (cT2) NSCLC.

CONCLUSIONS

The increasing numbers of harvested LNs and N2 level LNs were associated with better OS and DFS in cN0 NSCLC patients that were suitable for lobectomies. At least 17 LNs and 10 N2 level LNs were required to be harvested, especially in cT2 patients.

The significance of spread through air spaces in the prognostic assessment model of stage I lung adenocarcinoma and the exploration of its invasion mechanism

PURPOSE

Spread through air spaces (STAS) is a crucial invasive mode of lung cancer and has been shown to be associated with early recurrence and metastasis. We aimed to develop a prognostic risk assessment model for stage I lung adenocarcinoma based on STAS and other pathological features and to explore the potential relationship between CXCL-8, Smad2, Snail, and STAS.

METHODS

312 patients who underwent surgery at Harbin Medical University Cancer Hospital with pathologically diagnosed stage I lung adenocarcinoma were reviewed in the study. STAS and other pathological features were identified by H&E staining, and a prognostic risk assessment model was established. The expression levels of CXCL8, Smad2, and Snail were determined by immunohistochemistry.

RESULTS

The nomogram was established based on age, smoking history, STAS, tumor lymphocyte infiltration, tissue subtype, nuclear grade, and tumor size. The C-index for DFS was (training set 0.84 vs validation set 0.77) and for OS was (training set 0.83 vs validation set 0.78). Decision curve analysis showed that the model constructed has a better net benefit than traditional reporting. The prognostic risk score validated the risk stratification value for stage I lung adenocarcinoma. STAS was an important prognostic factor associated with stronger invasiveness and higher expression of CXCL8, Smad2, and Snail. CXCL8 was associated with poorer DFS and OS.

CONCLUSIONS

We developed and validated a survival risk assessment model and the prognostic risk score formula for stage I lung adenocarcinoma. Additionally, we found that CXCL8 could be used as a potential biomarker for STAS and poor prognosis, and its mechanism may be related to EMT.

Effects of pre-operative biopsy on recurrence and survival in stage I lung adenocarcinoma patients in China

Background

Whether pre-operative biopsy affects post-operative recurrence and metastasis of lung cancer patients is still controversial.

Methods

In order to clarify these disputes, we collected relevant literature to conduct a meta-analysis. To validate the results of the meta-analysis, we retrospectively analysed 575 patients with stage I lung adenocarcinoma who underwent surgical resection at our centre from 2010 to 2018 using propensity score matching and competing risk models.

Results

5509 lung cancer patients from 11 articles were included in the meta-analysis. Summary analysis showed that the total recurrence rate of the biopsy group was higher than that of the nonbiopsy group (risk ratio 1.690, 95% CI 1.220-2.330; p=0.001). After propensity score matching, we found that there was no significant correlation between biopsy and total recurrence (risk ratio 1.070, 95% CI 0.540-2.120; p=0.850). In our cohort, of 575 stage I lung adenocarcinomas, 113 (19.7%) patients underwent pre-operative biopsy. During a median (interquartile range) follow-up of 71 (57-93) months, multivariable analyses showed pre-operative biopsy in the overall observation cohort (subdistribution hazard ratio (SHR) 1.522, 95% CI 0.997-2.320; p=0.051) and in the propensity score-matched cohort (SHR 1.134, 95% CI 0.709-1.810; p=0.600) was not significantly correlated with the risk of recurrence and metastasis. Moreover, the pre-operative biopsy did not affect disease-free survival (SHR 0.853, 95% CI 0.572-1.273; p=0.438) or overall survival (SHR 0.647, 95% CI 0.352-1.189; p=0.161).

Conclusion

Pre-operative biopsy might not increase the risk of recurrence and metastasis, suggesting that these procedures might be safe for patients with stage I lung adenocarcinoma whose diagnosis is difficult to determine before surgery.

Intratumoral Microbiota-Host Interactions Shape the Variability of Lung Adenocarcinoma and Lung Squamous Cell Carcinoma in Recurrence and Metastasis

Differences in tissue microbiota-host interaction between lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD) about recurrence and metastasis have not been well studied. In this study, we performed bioinformatics analyses to identify the genes and tissue microbes significantly associated with recurrence or metastasis. All lung cancer patients were divided into the recurrence or metastasis (RM) group and the nonrecurrence and nonmetastasis (non-RM) group according to whether or not they had recurred or metastasized within 3 years after the initial surgery. Results showed that there were significant differences between LUAD and LUSC in gene expression and microbial abundance associated with recurrence and metastasis. Compared with non-RM, the bacterial community of RM had a lower richness in LUSC. In LUSC, host genes significantly correlated with tissue microbe, whereas host-tissue microbe interaction in LUAD was rare. Then, we established a novel multimodal machine learning model based on genes and microbes to predict the recurrence and metastasis risk of a LUSC patient, which achieves an area under the curve (AUC) of 0.81. In addition, the predicted risk score was significantly associated with the patient's survival. IMPORTANCE Our study elucidates significant differences in RM-associated host-microbe interactions between LUAD and LUSC. Besides, the microbes in tumor tissue could be used to predict the RM risk of LUSC, and the predicted risk score is associated with patients' survival.

Diastole/Body Mass Index Ratio Can Predict Post-Thoracoscopic Surgery Metastasis in Stage I Lung Adenocarcinoma

Background: According to recent animal models for lung adenocarcinoma metastasis, cardiac function may be related to the clinical outcome. The aim of this study is to identify a predictable index for postoperative metastasis (POM) that is associated with cardiac function. Methods. Two hundred and seven consecutive patients who underwent thoracoscopic resection for stage I lung adenocarcinoma were included. Disease-free survival (DFS), overall survival (OS), and patients’ clinical and pathological characteristics were analyzed. Results. Among the 207 patients, 17 cases demonstrated metastasis, 110 cases received a preoperative echocardiogram, and six cases had POM. Mitral valve peak A velocity, which is one of the left ventricular diastolic function parameters affected by BMI (MVPABMI), was associated with a negative factor for POM (hazard ratio (HR): 2.139, p = 0.019) and a poor 5-year DFS in the above median (100% vs. 87%, p = 0.014). The predictable rate increased from 30.7% to 75% when the MVPABMI was above the median = 3.15 in the solid subtype). Conclusions. MVPABMI is a novel index for POM prediction in early-stage lung adenocarcinoma. This is a pilot study and the first attempt at research to verify that the diastole and the BMI may be associated with POM in early-stage lung adenocarcinoma.

Validation of the novel International Association for the Study of Lung Cancer grading system and prognostic value of filigree micropapillary and discohesive growth pattern in invasive pulmonary adenocarcinoma

INTRODUCTION

The Pathology Committee of the International Association for the Study of Lung Cancer (IASLC) proposed a new histological grading system based on the combination of predominant and high-grade patterns in 2020.

MATERIALS AND METHODS

Pathological sections from 631 patients with stage I-III invasive lung adenocarcinoma were reviewed. We then determined the histological grade according to the new grading system and confirmed the pathological features that included the filigree micropapillary and discohesive growth pattern. Applying of the novel IASLC grading system in prognosis stratification was verified and the clinical significance of the pathological characteristics was explored.

RESULTS

Cox multivariable analysis revealed that in the stage I-III invasive lung adenocarcinoma, the IASLC grading system was significantly associated with disease-free survival (DFS) [hazard ratio (HR) = 1.419; 95 % confidence interval (CI): 1.040-1.937; P = 0.027] and overall survival (OS) (HR = 1.899; 95 % CI: 1.168-3.087; P = 0.010). In patients with IASLC Grades 1 and 2, the simultaneous presence of filigree micropapillary and discohesive growth pattern was significantly correlated with DFS (HR = 1.899; 95 % CI:1.168-3.087; P = 0.010). However, the filigree micropapillary and discohesive growth pattern did not affect the OS (HR = 2.786; P = 0.317). The competitive risk model revealed that in the stage I cohort, the simultaneous presence of filigree micropapillary and discohesive growth pattern was a risk factor for recurrence and metastasis [sub- distribution HR (SHR) = 1.987; 95 %CI: 1.122-3.518; P = 0.019].

CONCLUSION

Our study verified that the new prognostic stratification system was an effective stratification tool. Filigree micropapillary and discohesive growth pattern may also be risk factors for DFS, postoperative recurrence and metastasis.

Propofol maintains Th17/Treg cell balance in elderly patients undergoing lung cancer surgery through GABAA receptor

Propofol is widely used in clinical anesthesia due to its advantages of rapid onset and less adverse reactions. This study focused on the role of propofol in the balance of Th17/Treg in elderly patients with lung cancer during perioperative period. Patients undergoing lung cancer surgery were anesthetized by propofol or sevoflurane. Veinal blood was collected at different time points to evaluate the changes of Th17/Treg cell. Propofol better maintained the balance of Th17/Treg in vivo. The peripheral blood of patients with lung cancer was collected in vitro before surgery. Cluster of differentiation (CD)4⁺ T cells were obtained and then treated with propofol at different concentrations and γ-aminobutyric acid A (GABAA) receptor antagonists. Propofol affected Th17/Treg cell balance by increasing Th17 cells, decreasing Treg cells, thus elevating Th17/Treg ratio, and inhibited invasion and migration of lung cancer cells through GABAA receptor, which was counteracted by GABAA receptor inhibitors. Subsequently, tumor in situ model of lung cancer in aged mice was established. Propofol anesthetized mice had lower change of Th17/Treg ratio, higher survival rate and less metastasis. In brief, propofol regulated balance of Th17/Treg in elderly patients undergoing lung cancer surgery through GABAA receptor. Additionally, propofol could inhibit metastasis of lung cancer.

Clinical impact of number of lymph nodes dissected on postoperative survival in node-negative small cell lung cancer

OBJECTIVES

Small cell lung cancer (SCLC) is a lethal histologic subtype of lung cancer. Although the Commission on Cancer recommends pathological examination of at least 10 lymph nodes dissected (LNDs) for resected early-stage non-small cell lung cancer, its survival benefit of LNDs in patients with early-stage SCLC is unknown.

METHODS

The National Cancer Database was queried for SCLC patients with clinical stage I-II and clinical N0, NX disease per AJCC 7^th edition who had undergone lobectomy between 2004 and 2017. Overall survival of SCLC patients by the number of LNDs was compared using Log-rank tests. Univariate and multivariable Cox proportional hazards analyses were performed.

RESULTS

In total, 688 (42%), 311 (20%), 247 (16%), 196 (12%), 126 (8%), and 36 (2%) of 1,584 patients with early-stage SCLC had ≥10, 7-9, 5-6, 3-4, 1-2, and 0 LNDs, respectively. The sequential improvement in the HRs was no longer evident if the number of LNDs exceeds 4. Patients with ≥3 LNDs (n = 1,422) had a significantly longer overall survival than those with <3 LNDs (n = 162) (hazard ratio for death: 0.76, 95% confidence interval: 0.62-0.94, P = 0.0087). Multivariate analysis revealed that ≥3 LNDs was an independent factor for predicting overall survival (hazard ratio for death: 0.76, 95% confidence interval: 0.61-0.93, P = 0.0083).

CONCLUSIONS

Although we are reluctant to recommend a definitive "optimal number" of LNDs, our findings suggest the prognostic and therapeutic roles for performing ≥3 LNDs in patients with early-stage SCLC who undergo lobectomy.

The More Extensive the Spread through Air Spaces, the Worse the Prognosis Is: Semi-Quantitative Evaluation of Spread through Air Spaces in Pulmonary Adenocarcinomas

INTRODUCTION

The extent of spread through air spaces (STAS) is less investigated among patients with lung adenocarcinoma who underwent sublobar resection. Therefore, we aimed to evaluate the extent of STAS semi-quantitatively, to assess its prognostic impact on overall survival (OS) and recurrence-free survival (RFS), and to investigate the reproducibility of this assessment.

METHODS

The number of tumour cell clusters and single tumour cells within air spaces was recorded in three different most prominent areas (200x field of view). The extent of STAS was categorized into three groups, and the presence of free tumour cluster (FTC) was recorded.

RESULTS

Sixty-one patients were included. Recurrence was more frequent with higher grade (p = 0.003), presence of lymphovascular invasion (p = 0.027), and presence of STAS of any extent (p = 0.007). In multivariate analysis, presence of FTC (HR: 5.89; 95% CI: 1.63-21.26; p = 0.005) and more pronounced STAS (HR: 7.46; 95% CI: 1.60-34.6; p = 0.01) had adverse impact on OS and RFS, respectively. Concerning reproducibility, excellent agreement was found among STAS parameters (ICC range: 0.92-0.94).

DISCUSSION

More extensive STAS is an unfavourable prognostic factor in adenocarcinomas treated with sublobar resection. As the evaluation of extent of STAS is reproducible, further investigation is required to gather more evidence.

An In Silico Analysis Reveals an EMT-Associated Gene Signature for Predicting Recurrence of Early-Stage Lung Adenocarcinoma

Background:

The potential micrometastasis tends to cause recurrence of lung adenocarcinoma (LUAD) after surgical resection and consequently leads to an increase in the mortality risk. Compelling evidence has suggested the underlying mechanisms of tumor metastasis could involve the activation of an epithelial-mesenchymal transition (EMT) program. Hence, the objective of this study was to develop an EMT-associated gene signature for predicting the recurrence of early-stage LUAD.

Methods:

The mRNA expression data of patients with early-stage LUAD were downloaded from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) available databases. Gene Set Variation Analysis (GSVA) was first performed to provide an assessment of EMT phenotype, whereas Weighted Gene Co-expression Network Analysis (WGCNA) was constructed to determine EMT-associated key modules and genes. Based on the genes, a novel EMT-associated signature for predicting the recurrence of early-stage LUAD was identified using a least absolute shrinkage and selection operator (LASSO) algorithm and a stepwise Cox proportional hazards regression model. Kaplan-Meier survival analysis, receiver operating characteristic (ROC) curves and Cox regression analyses were used to estimate the performance of the identified gene signature.

Results:

GSVA revealed diverse EMT states in the early-stage LUAD. Further correlation analyses showed that the EMT states presented high correlations with several hallmarks of cancers, tumor purity, tumor microenvironment cells, and immune checkpoint genes. More importantly, Kaplan-Meier survival analyses indicated that patients with high EMT scores had worse recurrence-free survival (RFS) and overall survival (OS) than those with low EMT scores. A novel 5-gene signature ( AGL, ECM1, ENPP1, SNX7, and TSPAN12) was established based on the EMT-associated genes from WGCNA and this signature successfully predicted that the high-risk patients had a higher recurrence rate compared with the low-risk patients. In further analyses, the signature represented robust prognostic values in 2 independent validation cohorts (GEO and TCGA datasets) and a combined GEO cohort as evaluated by Kaplan-Meier survival ( P-value < .0001) and ROC analysis (AUC = 0.781). Moreover, the signature was corroborated to be independent of clinical factors by univariate and multivariate Cox regression analyses. Interestingly, the combination of the signature-based recurrence risk and tumor-node-metastasis (TNM) stage showed a superior predictive ability on the recurrence of patients with early-stage LUAD.

Conclusion:

Our study suggests that patients with early-stage LUAD exhibit diverse EMT states that play a vital role in tumor recurrence. The novel and promising EMT-associated 5-gene signature identified and validated in this study may be applied to predict the recurrence of early-stage LUAD, facilitating risk stratification, recurrence monitoring, and individualized management for the patients after surgical resection.

[Pattern of Recurrence and Metastasis after Radical Resection of Non-small Cell Lung Cancer]

The rate of recurrence and metastasis of non-small cell lung cancer after radical resection is still very high. The risk factors for recurrence and metastasis have been extensively studied, but the dynamic pattern of postoperative recurrence hazard over time is relatively lacking. The dynamic recurrence hazard rate curve is applied to describe the rate of recurrence at any point time among the "at-risk" patients. In this article, by reviewing the previous literature, the characteristics of the dynamic recurrence and metastasis pattern after radical resection of non-small cell lung cancer and the clinical factors affecting the recurrence and metastasis pattern are summarized, in order to screen out specific populations with high recurrence risk and give them personalized follow-up strategy and diagnosis and treatment.
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MUC13 promotes lung cancer development and progression by activating ERK signaling

Mucin 13 (MUC13) is a glycoprotein that is expressed on the cell surface and participates in the tumorigenesis of multiple malignancies, including pancreatic cancer, colorectal cancer and renal cancer. However, to the best of our knowledge, the expression levels and function of MUC13 in lung cancer progression have not yet been demonstrated. Therefore, the present study examined the expression pattern and regulatory role of MUC13 in lung cancer tumorigenesis. The results demonstrated that MUC13 was highly expressed in lung cancer tissues and cell lines compared with that in normal tissues and cell lines. Functionally, knockdown of MUC13 inhibited cell proliferation and enhanced the apoptosis of A549 and NCI-H1650 lung cancer cells. Furthermore, silencing of MUC13 suppressed the migration and invasion of lung cancer cells. Additionally, a xenograft tumor model demonstrated that knockdown of MUC13 delayed the development of the lung cancer xenograft and suppressed the expression of proliferation marker Ki-67 in tumor tissues. Mechanistically, MUC13 activated the ERK signaling pathway by enhancing the phosphorylation of ERK, JNK and p38 in lung cancer tissues compared with that in normal tissues. Knockdown of MUC13 inhibited the phosphorylation of ERK/JNK/p38 in A549 and NCI-H1650 cells. Overall, these findings suggested that MUC13 could act as an oncogenic glycoprotein to accelerate the progression of lung cancer via abnormal activation of the ERK/JNK/p38 signaling pathway and might serve as a therapeutic target for lung cancer treatment.

Vessel invasion as a predictive factor for recurrence after surgery in stage I lung adenocarcinoma

BACKGROUND

Patients with early-stage lung cancer who underwent R0 resection often encounter disease recurrence, especially during the early phase; thus, it is deemed vital to determine the predictive factors for recurrence after surgery. In this study, we aimed to identify the independent variables associated with recurrence after complete surgical resection of pathological stage I lung adenocarcinoma.

METHODS

We retrospectively reviewed the medical records of 169 patients who underwent pulmonary resection for primary lung adenocarcinoma pathological stage I with curative intent lung cancer surgery from 2015 to December 2018 at our institution for information on the recurrence of the disease.

RESULTS

Per the multivariate analysis, the presence of micropapillary pattern and vessel invasion were found to be independent predictors of disease recurrence after surgery (odds ratio [OR]: 9.36, 95% confidence interval [CI]: 2.42-36.2, P = 0.0012; and OR: 4.50, 95% CI: 1.52-13.4, P = 0.0068, respectively). Vessel invasion was also found to be an independent predictor of disease recurrence after surgery within a year (OR 11.4, 95% CI 3.08-42.5, P = 0.0003).

CONCLUSIONS

The presence of vessel invasion may help in distinguishing patients with the highest risk of early-phase disease recurrence after surgery. Patients with stage I adenocarcinoma with vessel invasion should undergo intensive surveillance after surgery.

Prognostic Value of Inflammatory Biomarkers in Patients With Stage I Lung Adenocarcinoma Treated With Surgical Dissection

Objective

Inflammation plays a crucial role in tumorigenesis and progression. Our purpose was to investigate the prognostic value of neutrophil-to-lymphocyte ratio (NLR), systemic inflammation response index (SIRI) and systemic immune-inflammation index (SII), and develop a nomogram to predict the cancer-specific survival (CSS) and disease-free survival (DFS) of stage I lung adenocarcinoma patients.

Methods

1431 patients undergoing surgical resection with pathologically confirmed stage I lung adenocarcinoma were reviewed. The optimal cut-off values for NLR, SII, and SIRI were defined by the receiver operating characteristic (ROC) curve. Cox proportional hazards regression analyses were performed to recognize factors significantly correlated with CSS and DFS to construct the nomogram. The value of adjuvant chemotherapy on model-defined high-risk and low-risk patients was further explored.

Results

The cohort had a median follow-up time of 63 months. Multivariate analysis revealed that higher NLR (≥2.606), higher SIRI (≥0.705), higher SII (≥580.671), later T stage, histological pattern with solid or micropapillary components and radiologic features with solid nodules were significantly associated with worse CSS and DFS. The concordance index (C-index) of the nomogram established by all these factors was higher than that of the TNM staging system both in CSS (validation set 0.778 vs 0.652) and DFS (validation set 0.758 vs 0.695). Furthermore, the value of the established nomogram on risk stratification in stage I lung adenocarcinoma patients was validated.

Conclusions

Higher NLR, SII and SIRI pretreatment were associated with worse survival outcomes. A practical nomogram based on these three inflammatory biomarkers may help clinicians to precisely stratify stage I lung adenocarcinoma patients into high- and low-risk and implement individualized treatment.

Genetic-pathological prediction for timing and site-specific recurrence pattern in resected lung adenocarcinoma

OBJECTIVES

We aimed to describe accurately the timing and site-specific recurrence pattern for surgical resected lung adenocarcinoma and develop genetic-pathological risk prediction models to guide individual postoperative surveillance strategies.

METHODS

We retrospectively analysed radiological, pathological and sequencing data concerning 9 common oncogenic driver mutations from 1531 patients with resected lung adenocarcinoma between 2008 and 2015. The first recurrence site and time-to-recurrence were recorded. Independent risk factors were identified by multivariable regression analysis and consequently incorporated into prediction models.

RESULTS

With a median follow-up of 53.2 months, postoperative recurrences were noted in 483 (31.5%) patients. Bone and brain recurrence tended to occur early (median 11.7 and 17.0 months, respectively) while thorax recurrence occurred later (median 22.2 months), which was validated across different tumour stages. EGFR mutation was an independent predictor for brain and bone recurrence and KRAS mutation for early recurrence. Both internal and external validation of the nomograms for brain and bone recurrence prediction showed optimal discrimination (concordance index: internal, 0.75 and 0.81, respectively; external, 0.77 and 0.84, respectively) and calibration. Recurrence occurred relatively evenly during the follow-up period in low-risk groups but mainly occurred within 2 years in high-risk groups.

CONCLUSIONS

Unique biological differences exist among lung adenocarcinoma leading to distinct patterns of recurrence. These user-friendly genetic-pathological nomograms may help physicians to better stratify patients and make individual postoperative follow-up plans.

Association of postoperative recurrence with radiological and clinicopathological features in patients with stage IA-IIA lung adenocarcinoma

OBJECTIVES

To retrospectively investigate whether radiological and clinicopathological characteristics were associated with the presence of stage IA-IIA lung adenocarcinoma in patients at high risk for a postoperative recurrence.

MATERIALS AND METHODS

Three hundred twelve patients with biopsy-proven node-negative early-stage (IA-IIA) lung adenocarcinoma met the inclusion criteria for this study. Demographics data and histopathological findings were collected from medical records. Computed tomography (CT) performed approximately 1 month before surgery was manually scored using 23 CT descriptors. Univariate analyses were applied to demonstrate an association between clinicopathological and radiological features and 2-/5-year recurrences. Multivariate logistic regression was performed to assess the ability of radiological and clinicopathological features to discriminate low and high-risk factors for recurrence. A ROC curve was used to evaluate prediction performance.

RESULTS

Univariate analysis revealed that the 2-year recurrence was associated with six radiological features and two clinicopathological features, while 5-year recurrence was associated with five radiological features and two clinicopathological features. A multivariate logistic regression model of combined clinicopathological and radiological features showed that stage IIA (OR = 2.87), solid texture (solid part > 50 %: OR = 4.81; solid part = 100 %: OR = 3.61), pleural attachment (OR = 3.97) and bronchovascular bundle thickening (OR = 2.16) were associated with the independent predictors of 2-year recurrence, and stage IIA (OR = 3.52), solid texture (solid part > 50 %: OR = 3.56; solid part = 100 %: OR = 2.44) and pleural attachment (OR = 4.57) were associated with 5-year recurrence. Combined radiological and clinicopathological features could be significant indicators of 2- and 5-year recurrences (AUC = 0.784 and AUC = 0.815, respectively).

CONCLUSIONS

The combination of radiological and clinicopathological features has the potential to help predict postoperative recurrence in patients with stage IA-IIA lung adenocarcinomas and guide oncologists and patients whether to undergo additional treatment after surgery.

Risk stratification model for patients with stage I invasive lung adenocarcinoma based on clinical and pathological predictors

Background

The aim of this study was to propose a new kind of pathological classification and further establish a prognostic model for resected stage I invasive adenocarcinoma (IADC).

Methods

Clinicopathological data were collected from 2 hospitals. The new proposed pathological reclassification was defined according to certain subtype instead of a predominant one. Survival curves were plotted by Kaplan-Meier analysis. Cox regressions were analyzed for recurrence-free survival (RFS) and overall survival (OS), through which prognostic scores and stratification models were established. The comparison between risk models and the eighth edition of tumor, node, metastasis (TNM) classification was conducted through receiver operating characteristic curves (ROC), as identified by the area under the curve (AUC) and z test.

Results

In all, 1,196 patients were enrolled. At multivariable analysis, solid and micropapillary of the new pathological reclassification, along with stage IA3 and IB were independent predictors for poorer RFS. Stage IB and smoking status significantly indicated worse OS. After normalization and standardization of log-hazard ratio (HR), personalized scores were calculated and the risk stratifications with 3 risk groups were generated. Compared with TNM classification, the risk model of RFS showed advantage over early-recurrence prediction (1-year: 0.653 vs. 0.556, P=0.033; 3-year: 0.663 vs. 0.076, P=0.008). No marked difference was observed in long-term RFS or OS.

Conclusions

Considering the harboring of certain patterns may be a new concept in adenocarcinoma classification. The risk stratification model based on this pathological classification and the eighth TNM classification showed remarkable superiority over TNM alone in predicting early recurrence of stage I adenocarcinoma. However, TNM classification remained valuable for long-term recurrence and survival prediction.

Can dosimetry affect local control and survival in patients with early-stage lung cancer treated with Stereotactic Ablative Radiotherapy (SABR)? An analysis of the UK's largest cohort of lung SABR patients

PURPOSE/OBJECTIVES

A recent study has shown that tight conformity of lung Stereotactic Ablative Radiotherapy (SABR) plans might worsen loco-regional control and can predict distant metastases. The study aims to report overall survival (OS), progression-free survival (PFS), local recurrence free survival (LRFS), and dosimetry of early-stage lung cancer patients treated with SABR and to try to explore any dosimetric predictor of outcomes.

MATERIAL AND METHODS

Patients treated in our institute (May 2009-August 2018) were included. Electronic medical records were reviewed for baseline characteristics, treatment details, and outcomes. Dosimetric data were extracted from Xio and Monaco software. Patients were treated according to the United Kingdom (UK) SABR consortium guidelines. Kaplan-Meier's analysis with log-rank test was used for survival analysis. The univariate and multivariable Cox regression model was used for correlating dosimetric variables and outcomes.

RESULTS

We treated 1266 patients with median age of 75 years and 47.4% were male. Median follow up was 56 months. Median OS was 36 months with 1, 2, and 5 years OS of 84.2%, 64.5%, and 31.5%, respectively. Median for PFS and LRFS was not reached. One, 2, and 5 years PFS were 87.4%, 78.4%, and 72.5%, respectively. One, 2, and 5 years LRFS were 98.2%, 95.1%, and 92.5%, respectively. Planning target volume (PTV), dose to 99% volume of PTV (D99), and R50 (volume receiving the 50% dose/volume (PTV)) were significantly associated with OS. PTV, mean lung dose (MLD), V20 (volume of lung minus gross tumour volume (GTV) receiving 20 Gy), V12.5 (volume of lung minus GTV receiving 12.5 Gy), and dose fractionation were significantly associated with PFS. Nothing was associated with LRFS on univariate analysis. R100 of >1.1 was associated with better OS, PFS, and LRFS compared to R100 ≤ 1.1.

CONCLUSION

SABR achieves good clinical outcomes in patients with early-stage lung cancer; even in elderly patients with multiple comorbidities. In the largest UK early lung cancer cohort treated with SABR, we found that dosimetry correlates with clinical outcomes. Further validation of these results is needed to guide future optimisation of SABR delivery.

miR‑454‑3p inhibits non‑small cell lung cancer cell proliferation and metastasis by targeting TGFB2

Accumulating studies have suggested that microRNAs (miRs) play a significant role in lung cancer development and progression, especially in non-small cell lung cancer (NSCLC). The present study aimed to investigate the associations between miR-454-3p and NSCLC progression. qPCR assay was applied to examine the expression of miR-454-3p and transforming growth factor-β2 (TGFB2) in tissues and cell lines. CCK-8 and EdU assays were used to detect cell proliferation. Wound-healing and Transwell assays were conducted to assess cell migration and invasion. Western blotting assay was performed to explore the protein levels of epithelial-mesenchymal transition (EMT) markers. The interaction between miR-454-3p and TGFB2 was investigated with a luciferase reporter assay. miR-454-3p was downregulated in NSCLC tissues and NSCLC cell lines. miR-454-3p overexpression led to the suppression of proliferation, migration, and invasion in A549 and NCI-H1650 cells. In addition, the overexpression of miR-454-3p in A549 and NCI-H1650 cells significantly inhibited EMT. TGFB2 was revealed to be a direct target of miR-454-3p by using TargetScan database and luciferase reporter assay. TGFB2 was observed to be upregulated in NSCLC tissues and cell lines. Further mechanistic studies revealed that the inhibitory effects of miR-454-3p on NSCLC were reversed upon overexpression of TGFB2. These findings provided strong evidence that miR-454-3p suppressed NSCLC cell proliferation and metastasis by targeting TGFB2. The study suggests that targeting miR-454-3p could be a promising strategy for treating NSCLC.

Clinical Outcomes and Prognostic Factors of Salvage Stereotactic Body Radiotherapy for Post-Surgical Thoracic Oligo-Recurrence/Metastasis of Non-Small-Cell Lung Cancer

Purpose

The study aimed to assess the efficacy and safety of stereotactic body radiotherapy (SBRT) using CyberKnife (CK) in patients with postoperative thoracic oligo-recurrence/metastasis of non-small-cell lung cancer (NLCLC), and to analyze the prognostic factors affecting overall survival after SBRT.

Patients and Methods

A total of 44 patients with postoperative thoracic oligo-recurrence/metastatic of NLCLC treated with SBRT were reviewed. Thoracic oligo-recurrence/was defined as 1–3 loco-regional confined to lung lobe, hilar/mediastinal lymph nodes, bronchial stump, or chest wall. Primary endpoints included local control (LC), overall survival (OS), progression-free survival (PFS) and toxicity. Prognostic factors that affected these patients were analyzed by the univariate and multivariate analysis by Kaplan–Meier methods and Cox regression models, respectively.

Results

The median follow-up time after salvage SBRT was 48.5 months. Measuring from the date of salvage SBRT, the median OS of the 44 patients was 52.60 (95% CI: 29.59–75.60) months. 1-,3-and 5-year OS rates were 97.7%, 65.3% and 47.7%, respectively. The 1-,3-year and 5-year LC rates were 97.7%, 85.1% and 80.1%, respectively. At 1, 3 and 5 years, the PFS rates were 77.1%, 28.8% and 5.3%, respectively. Multivariate analysis demonstrated that pre-SBRT neutrophil-to-lymphocyte ratio (NLR) and Charlson comorbidity index (CCI) were independent prognostic factors (p < 0.05). The treatment-related side-effects were well tolerated. No patients developed grade 3 or greater pulmonary toxicity.

Conclusion

SBRT is a promising salvage therapeutic option for postoperative thoracic oligo-recurrence/metastasis of non-small-cell lung cancer with acceptable toxicity. Low pre-SBRT neutrophil-to-lymphocyte ratio (NLR) and low Charlson comorbidity index (CCI) were associated with a better prognosis and longer survival and might be considered as reliable and independent prognostic factors in these patients treated with SBRT.

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.

Proteomic Analyses Identify Differentially Expressed Proteins and Pathways Between Low-Risk and High-Risk Subtypes of Early-Stage Lung Adenocarcinoma and Their Prognostic Impacts

The histopathological subtype of lung adenocarcinoma (LUAD) is closely associated with prognosis. Micropapillary or solid predominant LUAD tends to relapse after surgery at an early stage, whereas lepidic pattern shows a favorable outcome. However, the molecular mechanism underlying this phenomenon remains unknown. Here, we recruited 31 lepidic predominant LUADs (LR: low-risk subtype group) and 28 micropapillary or solid predominant LUADs (HR: high-risk subtype group). Tissues of these cases were obtained and label-free quantitative proteomic and bioinformatic analyses were performed. Additionally, prognostic impact of targeted proteins was validated using The Cancer Genome Atlas databases (n = 492) and tissue microarrays composed of early-stage LUADs (n = 228). A total of 192 differentially expressed proteins were identified between tumor tissues of LR and HR and three clusters were identified via hierarchical clustering excluding eight proteins. Cluster 1 (65 proteins) showed a sequential decrease in expression from normal tissues to tumor tissues of LR and then to HR and was predominantly enriched in pathways such as tyrosine metabolism and ECM-receptor interaction, and increased matched mRNA expression of 18 proteins from this cluster predicted favorable prognosis. Cluster 2 (70 proteins) demonstrated a sequential increase in expression from normal tissues to tumor tissues of LR and then to HR and was mainly enriched in pathways such as extracellular organization, DNA replication and cell cycle, and high matched mRNA expression of 25 proteins indicated poor prognosis. Cluster 3 (49 proteins) showed high expression only in LR, with high matched mRNA expression of 20 proteins in this cluster indicating favorable prognosis. Furthermore, high expression of ERO1A and FEN1 at protein level predicted poor prognosis in early-stage LUAD, supporting the mRNA results. In conclusion, we discovered key differentially expressed proteins and pathways between low-risk and high-risk subtypes of early-stage LUAD. Some of these proteins could serve as potential biomarkers in prognostic evaluation.

Thymosin β10 promotes tumor-associated macrophages M2 conversion and proliferation via the PI3K/Akt pathway in lung adenocarcinoma

Background

Thymosin β10 (TMSB10) has been reported to play a protumorigenic role in a majority of solid cancers. However, the existence of TMSB10 in immune microenvironment may contribute to the pathogenesis of lung adenocarcinoma has not been previously explored.

Method

TAMs-associated TMSB10 expression was evaluated by immunohistochemistry (IHC) in 184 lung adenocarcinomas. Xenograft mice model was established to investigate the effect of TMSB10 shRNA on TAMs phenotypes. The macrophages phenotype associated cytokines IL-6, IL-8, IL-12 and TNF-α were detected by ELISA after treated with TMSB10 shRNA or scramble. Furthermore, the target proteins were detected by immunoblotting.

Results

We found that high TAMs-associated TMSB10 expression was significantly correlated with the advanced TNM stage and T3/T4 tumor size. And high TAMs-associated TMSB10 expression was significantly correlated with poor overall and progression-free survival of lung adenocarcinoma, acting as an independent prognostic factor for lung adenocarcinoma. Furthermore, we investigated the biological functions of TMSB10 in macrophages in vivo and in vitro. TMSB10 knockdown dramatically reduced TAMs, THP-1 and RAW264.7 cell proliferation, and promoted macrophages phenotype conversion of M2 to M1, and TMSB10 knockdown reduced the levels of p-Akt (Sec473), p-mTOR (Sec2448) and p-p70S6K (Thr389) without effect on Akt, mTOR and p70S6K expression.

Conclusions

These results demonstrate that TAMs-associated TMSB10 promotes tumor growth through increasing TAMs M2 conversion and proliferation via PI3K/Akt signaling pathway, providing a promising tumor biomarker for predicting prognosis and a potential therapeutic target for lung adenocarcinoma.

Prognostic Significance of Lymph Node Count Removed at Sublobar Resection in Pathologic Stage IA Non-Small-cell Lung Cancer: A Population-Based Analysis

BACKGROUND

We sought to elucidate the associations between the examined lymph node (ELN) count and survival after sublobar resection (SLR) in pathologic stage IA non-small-cell lung cancer and assess the survival efficacy for patients undergoing SLR with an adequate ELN count compared with lobar resection (LR).

PATIENTS AND METHODS

The newly released U.S. Surveillance, Epidemiology, and End Results database was queried. The association between the ELN count in SLR and survival was analyzed using Cox regression and propensity score matching analyses. The optimal cutoff for the ELN count in SLR was determined using the Chow test and "segmented" function. Survival differences between SLR with an adequate ELN count and LR were compared using the log-rank test.

RESULTS

A total of 16,630 lobectomies, 3979 wedge resections, and 1119 segmentectomies were included in the present study. The median ELN count was 3 (interquartile range [IQR], 1-7), 1 (IQR, 0-4), and 7 (IQR, 4-12) for segmentectomy, wedge resection, and lobectomy, respectively (P < .001). The optimal cutoff for ELNs was 2.40 (IQR, 2.15-2.65) and 2.59 (IQR, 2.19-3.00) for patients undergoing wedge and segmental resection. SLR patients with ≥ 3 ELNs showed better overall survival and lung cancer-specific survival compared with those with < 3 ELNs. SLR patients with ≥ 3 ELNs had a noninferior prognosis compared with LR patients after matching of potential confounders.

CONCLUSIONS

In SLR, an adequate ELN count (≥ 3) could confer an improved prognosis compared with an inadequate ELN count (< 3). SLR patients with an adequate ELN count had noninferior survival outcomes compared with LR patients when the ELNs were well matched.

Early Distant Recurrence in Patients With Resected Stage I Lung Cancer: A Case Series of "Blast Metastasis"

BACKGROUND

The standard of care in the management of stage I non-small-cell lung cancer (NSCLC) has been anatomic lung resection with multistation lymph node sampling of ≥ 10 lymph nodes. The 5-year survival for NSCLC has ranged from 73% to 93% (for stage IB and stage IA, respectively) and will be more favorable for patients with fewer comorbidities and those with a higher state of premorbid functioning and who undergo surgical resection. Despite the positive prognosis for operable stage I NSCLC, a subset of patients will develop metastatic disease within as few as 12 months after resection. Using an institutional database, we have presented the data from 68 patients who had developed distant metastatic recurrence after resection of pathologic stage I NSCLC within 1 year after surgery.

PATIENTS AND METHODS

A retrospective study was conducted of a prospectively maintained intuitional database. The final cohort included patients with pathologic stage I NSCLC who had undergone anatomic resection but had subsequently presented with multiple sites of distant recurrence within 1 year. The study period extended from 2003 to 2020. Patients with broad local recurrence or recurrence at a single distant site were excluded. Kaplan-Meier analysis was used to estimate the 5-year survival.

RESULTS

A total of 2827 patients had undergone surgical resection for stage I NSCLC during the 17-year period and 68 met the criteria for inclusion. Most of the patients (n = 48) were smokers, and the dominant histologic type was adenocarcinoma (n = 37). After recurrence, 22 patients (33%) had undergone chemoradiotherapy and 19 (28%) had received chemotherapy alone. The mean and median overall survival were 23.7 and 14 months, respectively. The 5-year survival from recurrence and surgery were both 13.2%.

CONCLUSIONS

Limited data are available on the risk factors for early metastasis after resected stage I NSCLC. The results from our cohort have demonstrated poor survival after recurrence. These data might be the basis for determining a phenotype for patients prone to early widespread metastasis despite seemingly curative surgical resection.

Predictors of Distant Recurrence Following Stereotactic Body Radiation Therapy for Stage I Non-Small Cell Lung Cancer

OBJECTIVE

The objective of this study was to characterize patients at an increased risk of distant metastasis (DM) following stereotactic body radiation therapy (SBRT) for stage I non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

We identified patients undergoing SBRT for stage I NSCLC between 2005 and 2016. Patients with a prior lung cancer diagnosis, receiving a biological effective dose <100 Gy, or receiving chemotherapy were excluded. Patients underwent pretreatment staging and were classified according to the American Joint Committee for Cancer (AJCC) 8th edition staging. The primary endpoint was DM. The Kaplan-Meier method and the Cox proportional hazards model were used for survival analysis and to identify predictors of DM.

RESULTS

A total of 174 patients were included, with a median age 75 years (range, 49 to 96 y) and a median follow-up of 24 months (range, 3 to 123 mo). The 2- and 4-year cumulative incidences of DM were 14.2% and 19.1%, respectively. Patients who developed DM had worse overall survival versus patients developing a locoregional recurrence (P=0.023). On multivariable analysis, having stage IB disease (hazard ratio: 2.95; 95% confidence interval: 1.06-8.23; P=0.039) or a lower/middle lobe tumor (hazard ratio: 2.67; 95% confidence interval: 1.07-6.69; P=0.036) was associated with increased risk of DM. The 2-year cumulative incidences of DM were 10.9% and 35.7% (P=0.002) for patients with stage IA versus IB tumors, respectively, and 11.3% and 19.7% (P=0.049) for patients with upper lobe versus lower/middle lobe tumors, respectively.

CONCLUSIONS

Patients with stage IB disease or lower/middle lobe tumors may have an increased risk of DM following SBRT. Randomized controlled trials are needed to further identify patients who may benefit from adjuvant systemic therapy after SBRT for stage I NSCLC.

Radiomics nomogram for prediction disease-free survival and adjuvant chemotherapy benefits in patients with resected stage I lung adenocarcinoma

Background

Robust imaging biomarkers are needed for risk stratification in stage I lung adenocarcinoma patients in order to select optimal treatment regimen. We aimed to construct and validate a radiomics nomogram for predicting the disease-free survival (DFS) of patients with resected stage I lung adenocarcinoma, and further identifying candidates benefit from adjuvant chemotherapy (ACT).

Methods

Using radiomics approach, we analyzed 554 patients' computed tomography (CT) images from three multicenter cohorts. Prognostic radiomics features were extracted from computed tomography (CT) images and selected using least absolute shrinkage and selection operator (LASSO) Cox regression model to build a radiomics signature for DFS stratification. The biological basis of radiomics was explored in the Radiogenomics dataset (n=79) by gene set enrichment analysis (GSEA). Then a nomogram that integrated the signature with these significant clinicopathologic factors in the multivariate analysis were constructed in the training cohort (n=238), and its prognostic accuracy was evaluated in the validation cohort (n=237). Finally, the predictive value of nomogram for ACT benefits was assessed.

Results

The radiomics signature with higher score was significantly associated with worse DFS in both the training and validation cohorts (P<0.001). The GSEA presented that the signature was highly correlated to characteristic metabolic process and immune system during cancer progression. Multivariable analysis revealed that age (P=0.031), pathologic TNM stage (P=0.043), histologic subtype (P=0.010) and the signature (P<0.001) were independently associated with patients' DFS. The integrated radiomics nomogram showed good discrimination performance, as well as good calibration and clinical utility, for DFS prediction in the validation cohort. We further found that the patients with high points (point ≥8.788) defined by the radiomics nomogram obtained a significant favorable response to ACT (P=0.04) while patients with low points (point <8.788) showed no survival difference (P=0.7).

Conclusions

The radiomics nomogram could be used for prognostic prediction and ACT benefits identification for patient with resected stage I lung adenocarcinoma.

Circular RNA ABCB10 promotes non-small cell lung cancer progression by increasing E2F5 expression through sponging miR-584-5p

BACKGROUND/AIMS

CircABCB10 function as an endogenous miRNA sponge plays an important role in various tumors. This experimental design was based on circABCB10 to explore the pathogenesis of non-small cell lung cancer (NSCLC). Methods: CircRNA microarray was used to examine circRNA expression profiles in lung cancer from 3 NSCLC patients and paired healthy lung tissues. The expression of circABCB10 and miR-584-5p was detected by q-PCR. CCK-8, colony formation, and transwell assays to study the circABCB10 effects on tumor cell growth and cell migration invasiveness. To validate downstream target genes of circABCB10 and miR-584-5p detected by luciferase reporter assays. RT-qPCR and Western blotting were used to study E2F5 expression. The tumor growth was detected by nude mice in vivo. Results: We analyzed the human circRNA expression profile in NSCLC tissues. CircABCB10 was identified as a circRNA that increased in NSCLC tissues. CircABCB10 was noticeably raised in NSCLC, and high circABCB10 expression was related to low survival in NSCLC patients. Silencing of circABCB10 suppressed non-small cell lung cancer cell migration, cell proliferation, and invasion.CircABCB10 can act as a sponge of miR-584-5p to up-regulate E2F5 expression level. E2F5 knockdown or overexpress of miR-584-5p gene reversed the circABCB10 who has carcinogenic effects. There was a negative correlation expression between the circABCB10 and miR-584-5p gene, and There was a positive relationship between the expression of circABCB10 and E2F5 in NSCLC tumors. Conclusion: CircABCB10 promoted the progression of NSCLC by modulating the miR-584-5p/E2F5 axis.

ABBREVIATION

NSCLC: non-small cell lung cancer; circ RNA: circular RNA; miRNA: micro RNA.

Comparison of prognostic impact of lymphovascular invasion in stage IA non-small cell lung cancer after lobectomy versus sublobar resection: A propensity score-matched analysis

OBJECTIVES

Lymphovascular invasion (LVI) is a well-known poor prognostic factor after lobectomy for non-small cell lung cancer. However, the prognostic effect of LVI in patients who undergo sublobar resection has not been fully evaluated. Thus, we compared the prognostic impact of LVI in stage IA patients who underwent lobectomy or sublobar resection.

MATERIALS AND METHODS

We retrospectively reviewed the data from patients with stage IA NSCLC who underwent surgical resection between 2007 and 2016. The prognostic impact of LVI was calculated by the Cox proportional hazard regression model. To adjust for the differences in confounding variables between LVI-positive and LVI-negative patients, propensity score matching (PSM) was carried out in patients who underwent lobectomy or sublobar resection.

RESULTS

Among the stage IA NSCLC patients (n = 2134), 184 (8.6%) had been diagnosed with LVI, of whom 144 (8.9%) were in the lobectomy group (n = 1614) and 40 (7.7%) were in the sublobar resection group (n = 520). In multivariable analysis, LVI was a significant risk factor for both overall survival (OS) (hazard ratio [HR], 2.03; 95% confidence interval [CI], 1.39-2.96; p < 0.001) and recurrence-free survival (RFS) (HR, 2.31; 95% CI, 1.68-3.17; p < 0.001). After PSM, the prognostic impact of LVI was greater in the sublobar resection group (HR = 4.93 and 4.25 for OS and RFS, respectively) than in the lobectomy group (HR = 1.77 and 2.51 for OS and RFS, respectively).

CONCLUSIONS

The presence of LVI was significantly associated with worse OS and RFS in stage IA NSCLC patients. The prognostic impact of LVI was more pronounced in the sublobar resection group than in the lobectomy group.

The role of spread through air spaces (STAS) in lung adenocarcinoma prognosis and therapeutic decision making

Spread through air spaces (STAS) was included as a novel pattern of invasion in lung adenocarcinoma by the World Health Organization in 2015. Since then, multiple studies have investigated the association of STAS with clinicopathological and molecular features and its implication in the prognosis of early stage lung cancer patients undergoing different surgery types. The aim of this comprehensive review is to present current data on the role of STAS and its perspective in lung adenocarcinoma management.

Oncologic Outcomes of Surgery Versus SBRT for Non-Small-Cell Lung Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND

The optimal treatment of stage I non-small-cell lung carcinoma is subject to debate. The aim of this study was to compare overall survival and oncologic outcomes of lobar resection (LR), sublobar resection (SR), and stereotactic body radiotherapy (SBRT).

METHODS

A systematic review and meta-analysis of oncologic outcomes of propensity matched comparative and noncomparative cohort studies was performed. Outcomes of interest were overall survival and disease-free survival. The inverse variance method and the random-effects method for meta-analysis were utilized to assess the pooled estimates.

RESULTS

A total of 100 studies with patients treated for clinical stage I non-small-cell lung carcinoma were included. Long-term overall and disease-free survival after LR was superior over SBRT in all comparisons, and for most comparisons, SR was superior to SBRT. Noncomparative studies showed superior long-term overall and disease-free survival for both LR and SR over SBRT. Although the papers were heterogeneous and of low quality, results remained essentially the same throughout a large number of stratifications and sensitivity analyses.

CONCLUSION

Results of this systematic review and meta-analysis showed that LR has superior outcomes compared to SBRT for cI non-small-cell lung carcinoma. New trials are underway evaluating long-term results of SBRT in potentially operable patients.

Clinicopathological variables influencing overall survival, recurrence and post-recurrence survival in resected stage I non-small-cell lung cancer

BACKGROUND

To investigate clinicopathological variables influencing overall survival, overall recurrence, and post-recurrence survival (PRS) in patients who experienced curative-intent surgical resection of stage I non-small-cell lung cancer (NSCLC).

METHODS

We investigated a series of 1387 patients with stage I NSCLC who underwent surgical resection from 2008 to 2015. The effect clinicopathological factors on death, recurrence, and PRS were evaluated by Kaplan-Meier estimates and cox regression analysis.

RESULTS

Among the 1387 stage I patients, 301 (21.7%) experienced recurrence. The 5-year cumulative incidence of recurrence (CIR) for all patients was 20.2% and median PRS was 25.5 months. The older age (P = 0.036), p-stage IB (P = 0.001), sublobar resection(P<0.001), histology subtype (P<0.001), and lymphovascular invasion (LVI) (P = 0.042) were significantly associated with worse overall survival. Among 301 recurrent patients, univariable analysis indicated that p-stage IB (versus IA) (P<0.001), LVI (P<0.001) and visceral pleural invasion (VPI) (P<0.001) were remarkably correlated with the higher incidence of recurrence. Taking the effect of clinicopathological variables on PRS into consideration, smoking history (P = 0.043), non-adenocarcinoma (P = 0.013), high architectural grade of LUAD (P = 0.019), EGFR wild status (P = 0.002), bone metastasis (P =0.040) and brain metastasis (P = 0.042) were substantially related with poorer PRS. Multivariate analysis demonstrated that high architectural grade of LUAD (P = 0.008), brain metastasis (P = 0.010) and bone metastasis (P = 0.043) were independently associated with PRS.

CONCLUSION

In patients with resected stage I NSCLC, the older age, p-stage IB (versus IA), sublobar resection, histology subtype, and LVI were significantly associated with worse overall survival. P-stage IB (versus IA), LVI, and VPI were significantly correlated with the higher incidence of recurrence. High architectural grade of LUAD, brain metastasis and bone metastasis were independent risk factors with PRS.

miR-512-5p suppresses the progression of non-small cell lung cancer by targeting β-catenin

The oncogenic protein β-catenin is regulated by microRNAs (miRs) in non-small cell lung cancer (NSCLC). miR-512-5p is downregulated in NSCLC compared with healthy tissues and exhibits a tumour-suppressive effect. To study whether miR-512-5p acts on β-catenin to exert its anticancer effect in NSCLC, miR-512-5p mimic and inhibitor were transfected into NSCLC A549 and H1975 cells. miR-512-5p mimic inhibited the invasion of NSCLC cells and increased apoptosis, which suggested an inhibitory effect of miR-512-5p in NSCLC progression in vitro. By contrast, transfection with the miR-512-5p inhibitor resulted in the opposite effects. A dual-luciferase assay demonstrated that miR-512-5p complementarily bound to the 3′-untranslated region of β-catenin. miR-512-5p mimic suppressed the transcription and translation of β-catenin and reduced the expression of the downstream oncogenes cyclin D1 and matrix metalloproteinases, leading to the inhibition of Wnt/β-catenin signalling and subsequent inhibition of NSCLC tumourigenesis in vitro. In conclusion, miR-512-5p may function as a tumour suppressor in NSCLC by inhibiting the Wnt/β-catenin pathway.

Effect of thoracic paraspinal block-propofol intravenous general anesthesia on VEGF and TGF-β in patients receiving radical resection of lung cancer

The objective of this study is to compare the effects of paravertebral nerve block-propofol intravenous general anesthesia (PPA) and sevoflurane inhalation general anesthesia (SGA) on the expression of serum vascular endothelial growth factor (VEGF) and transforming growth factor beta (TGF-β) in patients undergoing radical resection of lung cancer.Patients undergoing radical resection of lung cancer were divided into PPA group and SGA group. In PPA group, thoracic paraspinal nerve block was performed with 0.5% ropivacaine (2 mg/kg) before general anesthesia. Anesthesia was maintained with 2.5-3.5 μg/mL TCI of propofol. In SGA group, anesthesia was maintained with 1.0-1.5 MAC sevoflurane. The dosage of opioids during and 24 h after operation, the pain score at 2, 8, 24, 48, and 72 h after operation, and the concentrations of serum VEGF and TGF-β before and 24 h after operation were observed in the two groups.The intraoperative dosage of remifentanil in PPA group was significantly less than that in SGA group (P < 0.05). The dosage of sufentanil in SGA group was significantly less than that in SGA group at 24 h after operation (P < 0.05). The VAS score at 2, 8, and 24 h after operation was significantly lower than that in SGA group (P < 0.05). The serum VEGF and TGF-β concentration in PPA group was significantly lower than that in SGA group (P < 0.05).Thoracic paravertebral nerve block-propofol intravenous general anesthesia can reduce the dosage of opioids, improve the effect of postoperative analgesia, and reduce the serum concentration of tumor angiogenesis-related factors in patients undergoing radical resection of lung cancer.

Lung Adenocarcinoma has a Higher Risk of Lymph Node Metastasis than Squamous Cell Carcinoma: A Propensity Score-Matched Analysis

BACKGROUND

Controversy still exists in which subtype of non-small-cell lung cancer [squamous cell carcinoma (SCC) or adenocarcinoma] is more likely to have lymph node (LN) metastasis. The aim of this study is to compare the pattern of LN metastasis in two cohorts of matched patients surgically treated for SCC or adenocarcinoma.

METHODS

A retrospective analysis of patients undergoing lobectomy or segmentectomy with systematic lymphadenectomy without preoperative treatment for lung SCC or adenocarcinoma was conducted in this study. Data for analysis consisted of age, gender, tumor size, lobe-specific tumor location, tumor location (peripheral or central), and pathologic findings. We conducted the propensity score-matched (PSM) analysis to eliminate potential bias effects of possible confounding factors.

RESULTS

From January 2015 to December 2016 in our department, we finally included a total of 387 patients (including 63 patients with SCC and 324 patients with adenocarcinoma) for analysis. For the unmatched cohort, there was no sufficient evidence of significantly different number of positive LNs (P = 0.90) and rate of LN metastasis (P = 0.23) between SCC patients and adenocarcinoma patients. However, potential confounding factors, for example gender, tumor size, tumor location, tumor differentiation, and total number of dissected LNs, were significantly different between patients with SCC and those with adenocarcinoma. In the analysis of matched cohort after PSM analysis, those above confounding factors were comparable between the two groups. However, patients with adenocarcinoma had significantly more mean positive LNs (2.2 and 0.7; P = 0.008) and a higher rate of LN metastasis (53% and 29%; P = 0.016) than those with SCC.

CONCLUSIONS

Lung adenocarcinoma had a higher risk of LN metastasis than SCC, suggesting that different therapeutic modalities may be indicated for the two different subtypes of lung cancer.

Prognostic Impact of Tumor Spread Through Air Spaces in Non-small Cell Lung Cancers: a Meta-Analysis Including 3564 Patients

Surgical resection is the most effective treatment for early stage lung adenocarcinoma. However, the rate of 5-year postoperative recurrence reaches 30%, Spread Through Air Spaces(STAS) is a recently described novel invasive pattern of lung cancer, According to the 2015 WHO classification. STAS is defined as"micropapillary clusters, solid nests, or single cells spreading within air spaces beyond the edge of the main tumor, However, the prognostic role of STAS in lung cancer is not known, The aim of the current study is to evaluate the association between STAS and clinical outcome of lung cancer patients after surgical resection through a meta-analysis. Systematic research was conducted using three online databases to search for studies published before August 1, 2018. The 5-year RFS and OS for non-small cell lung cancer patients after surgical resection with or without STAS were compared. The studies were selected according to rigorous inclusion and exclusion criteria. Meta-analysis was performed using hazard ratio (HR) and 95% confidence intervals (CIs) as effective measures. Included in our meta-analysis were 12 studies, published from 2015 to 2018, with a total of 3564 patients. Our results clearly depicted that the presence of STAS predicted a worse outcome for 5-year RFS with the combined HR of 1.84(95% CI: 1.59-2.12). Meta-analysis of these 8 studies showed that patients with the presence of STAS were associated with shorter 5-year OS (the pooled HR:1.78, 95% CI: 1.51-2.11). This meta-analysis illuminated that the presence of STAS might be a unfavorable prognostic factor for patients with NSCLC. it should be paid sufficient attention and recorded in pathologic reports, which can indicate treatment choice and prognosis of patients. In future, more studies with well-designed and large-scale are needed to confirm the conclusion.

[Research Progress of Lymph Node Micrometastasis in Non-small Cell Lung Cancer]

The incidence and mortality of lung cancer rank top in China. One important factor is the occurrence of metastasis. With the development of science technology, the effect of surgical treatment on lung cancer is improved. Moreover, the use of targeted therapy has achieved a new height for the treatment of lung cancer. However, the recurrence rate remains high even the tumor was completely resected at early stage. The occurrence of lymph node micrometastasis is considered as one of the plausible explanations. The difficulty indetecting micrometastasis has been greatly reduced. Although studies dig deeper into the lymph node micrometastasis, there are still some controversies including the selection of surgical procedures, the pathological staging and prognosis about patients with lymph node micrometastasis. This review manages to generalize the latest research progress of lymph node micrometastasis.
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Proposal on incorporating lymphovascular invasion as a T-descriptor for stage I lung cancer

BACKGROUND

Lymphovascular invasion (LVI) and Visceral Pleural Invasion (VPI) have been reported to be risk factors for stage I Non-Small Cell Lung Cancer (NSCLC). However, only VPI was incorporated into the current 8th Tumor-Node-Metastasis (TNM) classification. This study aimed to explore the prognostic effect of LVI and VPI on TNM staging in pathological stage I NSCLC.

METHOD

We retrospectively reviewed 2633 consecutive p-stage I NSCLC patients in the Shanghai Chest Hospital (2008-2012). By using the Kaplan-Meier method and Cox proportional hazard regression model, we identified the correlations between LVI, VPI, and clinical outcomes in p-stage 1 NSCLC.

RESULTS

Of all 2633 p-stage I NSCLC patients, 222 were pathologically diagnosed with LVI and 836 pathologically with VPI. The 5-year recurrence free survival (RFS) and overall survival (OS) rates of patients with LVI was significantly worse compared to those without LVI (61.2% vs 82.0%, p < 0.001; 73.3% vs 88.1%, p < 0.001). The same results emerged for patients with VPI (70.1% vs 85.9%, p < 0.001; 82.3% vs 90.0%, p < 0.001). Using the univariable and multivariable analysis, we found that when tumor diameter was 3 cm or smaller, LVI (RFS: hazard ratio [HR], 2.54; 95% confidence interval [CI], 1.86-3.50; p < .001; OS: HR, 2.53; 95% CI, 1.72-3.71; p < .001) and VPI (RFS: HR, 2.14; 95% CI, 1.71-2.67; p < .001; OS: HR, 1.56; 95% CI, 1.12-2.04; p = 0.01) were significant prognostic factors for RFS and OS. When tumor size was between 3-4 cm, LVI (HR, 1.84; 95% CI, 1.03-3.29; p = 0.039) and VPI (HR, 2.56; 95% CI, 1.61-4.07; p < .001) were associated with inferior OS.

CONCLUSIONS

The presence of LVI significantly affected OS and RFS in stage I NSCLC patients. Our results suggested that it might be better to incorporate LVI as a T descriptor as VPI in the further TNM classification.

Development and Validation of Web-Based Nomograms to Precisely Predict Conditional Risk of Site-Specific Recurrence for Patients With Completely Resected Non-small Cell Lung Cancer: A Multiinstitutional Study

BACKGROUND

There is currently no consensus regarding the optimal postoperative follow-up strategy for patients with completely resected non-small cell lung cancer (NSCLC). We aimed to develop web-based nomograms to precisely predict site-specific postoperative recurrence in patients with NSCLC and to guide individual surveillance strategies including when to follow up and what diagnostic tests to perform.

METHODS

We investigated the pattern of recurrence in a series of 2,017 patients with NSCLC (squamous cell carcinoma and nonlepidic invasive adenocarcinoma) who underwent complete surgical resection at Fudan University Shanghai Cancer Center (development cohort), and developed web-based clinicopathologic prediction models for conditional risk of site-specific recurrence based on Cox regression. The variables used in the analysis included sex, age, smoking history, tumor size, tumor histology, lymphovascular invasion, visceral pleural invasion, and pathologic TNM stage. A separate cohort of 3,308 patients with NSCLC from Shanghai Chest Hospital was used for external validation.

RESULTS

In the development cohort and the external validation cohort for the established nomograms to predict overall recurrence, thorax recurrence, abdomen recurrence, neck recurrence, brain recurrence, and bone recurrence, the C-statistics of Harrell et al were 0.743 and 0.748, 0.728 and 0.703, 0.760 and 0.749, 0.779 and 0.757, 0.787 and 0.784, and 0.777 and 0.739, respectively. The calibration plots showed optimal agreement between nomogram-predicted 3-year recurrence-free survival and actual 3-year recurrence-free survival.

CONCLUSIONS

These user-friendly nomograms can precisely predict site-specific recurrence in patients with completely resected NSCLC, based on clinicopathologic features. They may help physicians to make individual postoperative follow-up plans.

Can dose outside the PTV influence the risk of distant metastases in stage I lung cancer patients treated with stereotactic body radiotherapy (SBRT)?

BACKGROUND AND PURPOSE

In an era where little is known about the "abscopal" (out-of-the-field) effects of lung SBRT, we investigated correlations between the radiation dose proximally outside the PTV and the risk of cancer recurrence after SBRT in patients with primary stage I non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

This study included 217 stage I NSCLC patients across 2 institutions who received SBRT. Correlations between clinical and dosimetric factors were investigated. The clinical factors considered were distant metastasis (DM), loco-regional control (LRC) and radiation pneumonitis (RP). The dose (converted to EQD2) delivered to regions of varying size directly outside of the PTV was computed. For each feature, area under the curve (AUC) and odds ratios with respect to the outcome parameters DM, LRC and RP were estimated; Kaplan-Meier (KM) analysis was also performed.

RESULTS

Thirty-seven (17%) patients developed DM after a median follow-up of 24 months. It was found that the mean dose delivered to a shell-shaped region of thickness 30 mm outside the PTV had an AUC of 0.82. Two years after treatment completion, the rate of DM in patients where the mean dose delivered to this region was higher than 20.8 Gy₂ was 5% compared to 60% in those who received a dose lower than 20.8 Gy₂. KM analysis resulted in a hazard ratio of 24.2 (95% CI: 10.7, 54.4); p < 10^-5. No correlations were found between any factor and either LRC or RP.

CONCLUSIONS

The results of this study suggest that the dose received by the region close to the PTV has a significant impact on the risk of distant metastases in stage I NSCLC patients treated with SBRT. If these results are independently confirmed, caution should be taken, particularly when a treatment plan results in a steep dose gradient extending outwards from the PTV.