Correlation between Skip N2 Metastases and SUVmax, Long Diameter of Tumor, and Ki67 Expression in Patients with Non-Small-Cell Lung Cancer

Rapid intraoperative Ki-67 immunohistochemistry for lung cancer using non-contact alternating current electric field mixing

OBJECTIVES

Locoregional recurrence of non-small cell lung cancer (NSCLC) occurs even among patients with stage I disease, as a result of tumor proliferative activity. The aim of this study was to evaluate the clinical reliability of a new rapid immunohistochemistry (IHC) technique for assessing malignant potential through detection of tumoral Ki-67 expression.

MATERIALS AND METHODS

The rapid IHC method uses non-contact alternating current (AC) mixing to achieve more rapid/stable staining within 20 min during surgery. First, to investigate the association between clinical outcomes and tumoral Ki-67 labeling with rapid IHC, 21 pairs of surgical patients treated between 2012 and 2020 for pStage IA1-3 NSCLC with/without recurrence were retrospectively reviewed. Second, 40 frozen section (FS) samples in patients with NSCLC for whom radical surgery was planned between April 2021 and February 2022 were deemed eligible for comparison of the clinical performance of conventional IHC and intraoperative rapid Ki-67 IHC with FS.

RESULTS

Detection of tumoral Ki-67 expression using rapid IHC with formalin-fixed, paraffin-embedded (FFPE) blocks was significantly associated with clinical outcomes in R0 pStage IA NSCLC surgical patients, including overall and recurrence-free survival (P = 0.0043 and P < 0.0001, respectively). Levels of Ki-67 expression among resectable NSCLC patients detected using rapid IHC with FS significantly correlated with those detected using conventional FFPE-IHC (p < 0.001). An intraoperative cut-off of > 7.5 % tumor cell Ki-67 positivity accurately predicted pathological stage more advanced than IA3 [P = 0.0185, Odds ratio = 20.477, 95 % confidence interval (CI): 1.660-252.55].

CONCLUSION

Rapid Ki-67 IHC with AC mixing could potentially serve as a clinical tool for intraoperative determination of tumor malignancy status. The present study suggests that segmentectomy for early small NSCLCs is oncologically safe and a reasonable alternative to lobectomy, but only when there is adequate intraoperative selection for primary tumors with low-grade malignancy, which could be verified using intraoperative rapid Ki-67 IHC with FS.

Slug and Vimentin downregulation at the metastatic site is associated with Skip-N2 metastasis of lung adenocarcinoma

OBJECTIVE

Lung cancer displays heterogeneity both in the tumor itself and in its metastatic regions. One interesting behavior of the tumor is known as Skip N2 metastasis, which N2 lymph nodes contain tumor cells while N1 are clean. In this study, mRNA levels of epithelial mesenchymal transition (EMT) related genes in skip N2 and normal N2 involvements of non-small cell lung cancer tissues were investigated to evaluate the possible molecular background that may contribute to the pathogenesis of Skip N2 metastasis.

MATERIALS AND METHODS

Eighty-three surgically resected and paraffin embedded lymph node samples of lung cancer patients were analyzed in this study, which 40 of them were Skip N2. N2 tissues were sampled from 50% tumor containing areas and total RNA was extracted. mRNA levels for 18S, E-cadherin, Vimentin, ZEB1 and SLUG were analyzed via qPCR and E-cadherin and vimentin protein levels via immunohistochemistry (IHC). Bioinformatic analysis were adopted using online datasets to evaluate significantly co-expressed genes with SLUG in lung cancer tissue samples.

RESULTS

Skip-N2 patients who had adenocarcinoma subtype had better survival rates. Comparative analysis of PCR results indicated that Skip N2 tumor tissues had increased E-Cadherin/Vimentin ratio and ZEB1 mRNA expression, and significantly decreased levels of SLUG. E-cadherin IHC staining were higher in Skip N2 and Vimentin were in Non-Skip N2. TP63 had a strong correlation with SLUG expression in the bioinformatics analyses.

CONCLUSION

The results indicate that, at molecular level, Skip N2 pathogenesis has different molecular background and regulation of SLUG expression may orchestrate the process.

Postoperative long-term survival of non-small cell lung cancer patients with skip-N2 metastases

OBJECTIVE

Radical lymphadenectomy is crucial in operations for non-small cell lung cancer (NSCLC). Usually pN1 and pN2 lymph nodes are affected consecutively (N1N2). Nevertheless, pN2 metastases may also occur in the absence of pN1 as skip-N2 metastases (N0N2). Here we compare the long-term survival of N1N2- and N0N2 patients.

MATERIALS AND METHODS

464 patients underwent surgery for NSCLC at our institution between 2012 and 2017. We retrospectively reviewed data of pN2 stage patients (n = 68). Patients with N1N2 (n = 39) were compared to N0N2 (n = 29) patients. 1-, 3-and 5-year survival rates were measured. Survival was assessed by Kaplan-Meier curves and the cox proportional hazards model was used to identify prognostic factors for overall survival. All patients received adjuvant chemoradiation therapy according to European guidelines.

RESULTS

The baseline characteristics did not differ between groups. We observed no differences in the histology, localization, or gender in our cohort. N0N2 patients showed significantly better 1- (N1N2: 82.4% vs. N0N2 100%; p = 0.001), 3- (14.7% vs. 63.6%; p=<0.001) and 5-year (9.4% vs. 43.8%; p = 0.001) survival rates. Tumor size (Hazard ratio (HR) 1.46, Confidence interval (CI 95%) 1.03-2.04; p = 0.03) and the occurrence of N1N2 (HR 4.26, CI 2.04-8.91; p < 0.0001) were independent prognostic factors for worse long-term survival. The Kaplan-Meier curves showed a reduced overall survival for N1N2 patients (log-rank N1N2, N0N2 p < 0.0001).

CONCLUSION

N1N2 patients have a significantly worse prognosis compared to N0N2 patients. This will aid to classify the heterogeneous pN2-NSCLC patient population more precisely. Further, multimodal therapy should be considered for N1N2 patients.