The Study of Tumor Volume as a Prognostic Factor in T Staging System for Non-Small Cell Lung Cancer: An Exploratory Study

Impact of lymph node dissection on the efficacy of immune checkpoint inhibitors in patients with postoperative recurrence of non-small cell lung cancer

Background

The effect of lymph node dissection (LND) on the efficacy of immune checkpoint inhibitor (ICI) remains unclear. The purpose of this study was to examine the difference in the effect of ICI between patients with non-small cell lung cancer (NSCLC) according to the extent of LND performed in surgery prior to postoperative recurrence.

Methods

A total of 134 patients with postoperative recurrence (surgery group, n=26) or unresectable advanced lung cancer (non-surgery group, n=108) who were treated with ICIs between January 2016 and December 2022 were included for analysis. In the surgery group, 16 patients underwent systematic LND, whereas the remaining 10 patients underwent selective LND. Progression-free survival with ICI treatment (ICI-PFS) and overall survival (OS) were compared between the surgery and non-surgery groups and between the systematic and selective LND groups using the inverse probability of treatment weighting (IPTW) method to adjust for patient background characteristics.

Results

In the IPTW-adjusted analysis, the 2-year PFS rate with ICI treatment was 31.2% in the surgery group and 27.3% in the non-surgery group (P=0.19); the corresponding 2-year OS rates were 69.6% and 62.2%, respectively (P=0.10). In the surgery group, the 2-year PFS rates under ICI were 20.0% in the systematic LND group and 45.7% in the selective LND group (P=0.03).

Conclusions

IPTW-adjusted analysis indicated no difference in prognosis between patients with postoperative recurrence and those with advanced unresectable lung cancer. However, in patients with postoperative recurrence, the extent of LND was a significant predictor of ICI-PFS. These findings suggest that systematic LND may reduce the efficacy of ICI, indicating that preoperative ICI administration may be warranted.

A Novel Tissue-Free Method to Estimate Tumor-Derived Cell-Free DNA Quantity Using Tumor Methylation Patterns

Estimating the abundance of cell-free DNA (cfDNA) fragments shed from a tumor (i.e., circulating tumor DNA (ctDNA)) can approximate tumor burden, which has numerous clinical applications. We derived a novel, broadly applicable statistical method to quantify cancer-indicative methylation patterns within cfDNA to estimate ctDNA abundance, even at low levels. Our algorithm identified differentially methylated regions (DMRs) between a reference database of cancer tissue biopsy samples and cfDNA from individuals without cancer. Then, without utilizing matched tissue biopsy, counts of fragments matching the cancer-indicative hyper/hypo-methylated patterns within DMRs were used to determine a tumor methylated fraction (TMeF; a methylation-based quantification of the circulating tumor allele fraction and estimate of ctDNA abundance) for plasma samples. TMeF and small variant allele fraction (SVAF) estimates of the same cancer plasma samples were correlated (Spearman's correlation coefficient: 0.73), and synthetic dilutions to expected TMeF of 10-3 and 10-4 had estimated TMeF within two-fold for 95% and 77% of samples, respectively. TMeF increased with cancer stage and tumor size and inversely correlated with survival probability. Therefore, tumor-derived fragments in the cfDNA of patients with cancer can be leveraged to estimate ctDNA abundance without the need for a tumor biopsy, which may provide non-invasive clinical approximations of tumor burden.

Tumor Volume is a Better Prognostic Factor than Greatest Tumor Diameter in operated Stage I-III Non-small Cell Lung Cancer

INTRODUCTION

The aim of this study was to investigate the prognostic impact of tumor volume (TV, recorded from surgical specimens) on patients with stage I-III non-small-cell lung cancer (NSCLC) after complete resection.

MATERIALS AND METHODS

A total of 129 patients with stage I-III NSCLC diagnosed and underwent curative resection from 2007 to 2014 in our center were included in the study. Their clinico-pathological factors were retrospectively reviewed. Overall survival (OS) and disease-free survival (DFS) analyses were performed with the Kaplan-Meier method and Cox's hazard model. According to the ROC analysis, patients were divided into 2 groups (Group 1: 58 patients <30.3 cm³ and Group 2: 71 patients ≥30.3 cm³) and the OS and DFS values were compared.

RESULTS

Median TVs and greatest tumor diameter were 12 cm³ (0.1-30) / 3 cm (0.4-6.5) in Group 1 and 98 cm³ (30.6-1521) / 6 cm (3.5-21) in Group 2. Median OS was 53 (5-177) months in Group 1 and 38 (2-200) months in Group 2 (P < .001). DFS was similar in both group (28 [1-140] vs. 24 [1-155] months, Introduction P = .489). Kaplan-Meier curves showed significantly higher OS rates in Group 1 than Group 2 (P = .04). In multivariable analysis (TV, tumor T stage, tumor N stage, receiving adjuvant radiotherapy) showed that TV (HR: 0.293, 95% CI: 0.121-0.707, P = .006) and tumor N stage (HR: 0.013, 95% CI: 0.001-0.191, P = .02) were independent factors associated with OS.

CONCLUSION

Tumor volume, not considered in the routine TNM classification, may improve prediction accuracy of overall OS in operated Stage I-III NSCLC.