Validation of the IASLC Residual Tumor Classification in Patients With Stage III-N2 Non-Small Cell Lung Cancer Undergoing Neoadjuvant Chemoradiotherapy Followed By Surgery.

OBJECTIVE

The aim of this study was to validate the International Association for the Study of Lung Cancer (IASLC) residual tumor classification in patients with stage III-N2 non-small cell lung cancer (NSCLC) undergoing neoadjuvant concurrent chemoradiotherapy (nCCRT) followed by surgery.

BACKGROUND

As adequate nodal assessment is crucial for determining prognosis in patients with clinical N2 NSCLC undergoing nCCRT followed by surgery, the new classification may have better prognostic implications.

METHODS

Using a registry for thoracic cancer surgery at a tertiary hospital in Seoul, Korea, between 2003 and 2019, we analyzed 910 patients with stage III-N2 NSCLC who underwent nCCRT followed by surgery. We classified resections using IASLC criteria: complete (R0), uncertain (R[un]), and incomplete resection (R1/R2). Recurrence and mortality were compared using adjusted subdistribution hazard model and Cox-proportional hazards model, respectively.

RESULTS

Of the 96.3% (n = 876) patients who were R0 by Union for International Cancer Control (UICC) criteria, 34.5% (n = 3O2) remained R0 by IASLC criteria and 37.6% (n = 329) and 28% (n = 245) migrated to R(un) and R1, respectively. Most of the migration from UICC-R0 to lASLC-R(un) and IASLC-R1/R2 occurred due to inadequate nodal assessment (85.5%) and extracapsular nodal extension (77.6%), respectively. Compared to R0, the adjusted hazard ratios in R(un) and R1/R2 were 1.20 (95% confidence interval, 0.94-1.52), 1.50 (1.17-1.52) ( P fortrend = .001) for recurrence and 1.18 (0.93-1.51) and 1.51 (1.17-1.96) for death ( P for trend = .002).

CONCLUSIONS

The IASLC R classification has prognostic relevance in patients with stage III-N2 NSCLC undergoing nCCRT followed by surgery. The IASLC classification will improve the thoroughness of intraoperative nodal assessment and the completeness of resection.