The role of extensive lymph node dissection in the new grading system for lung adenocarcinoma

This study evaluates the prognostic impact of the new grading system for lung adenocarcinoma, stratified by lymphadenectomy extent.

We analyzed 1258 lung adenocarcinoma patients who underwent curative resections between 2006 and 2017. We analyzed overall survival (OS), cancer-specific survival (CSS), and recurrence-free survival (RFS) across tumor grades and lymphadenectomy extent, categorized as IASLC-R0 (complete resection) or R(un) (uncertain resection).

The median age of cohort was 63 and 41.9 % were male. The majority had undergone lobectomy. The distribution of tumors was 274 grade 1, 558 grade 2, and 426 grade 3 cases. After a median follow-up time of 102 months, the 10-year OS/CSS/RFS rates worsened significantly across grade 1-3: 92.4/99.3/92.3 %, 77.8/87.5/71.7 %, and 63.6/70.2/52.0 %, respectively (p < 0.001). Multivariate Cox regression analysis identified grade 3, R(un) lymphadenectomy, higher Charlson Comorbidity Index, smoking history, thoracotomy, higher pathology stage, and angiolymphatic invasion as independent prognostic factors for lower OS, CSS, and RFS. Furthermore, grade 3 patients benefited significantly from IASLC-R0 lymphadenectomy, showing significantly better OS and RFS than those who underwent R(un) lymphadenectomy (p = 0.007 for OS, p = 0.001 for RFS, post-propensity score matching). Among grade 3 tumors underwent R0 or R(un) resections found the incidence rates of local, distant, and simultaneous local and distant recurrence were 8.5 % vs 13.7 %, 11.0 % vs 12.2 %, and 11.0 % vs 20.6 %, respectively.

Surgical outcomes for lung adenocarcinoma have declined across grades 1-3. IASLC-R(un) treatment worsens OS and RFS in grade 3. Intensive monitoring and adjuvant therapy should be considered when patients with grade 3 lung adenocarcinoma undergo R(un) lymphadenectomy.