IASLC tumor budding grade identifies high-risk patients with resected lung squamous cell carcinoma

Researchers presented findings at the IASLC 2026 World Conference on Lung Cancer suggesting a new grading system using tumor budding could identify high-risk patients with resected lung squamous cell carcinoma (SqCC). The study, conducted retrospectively, reviewed 585 consecutive patients treated at Yonsei University Medical Center between 2015 and 2022.

The new International Association for the Study of Lung Cancer (IASLC) system classifies resected SqCC as low or high grade based solely on tumor budding. The research found 11.1% of patients had high-grade tumors, which were associated with more advanced disease stages and worse overall and disease-free survival.

When examining patients eligible for adjuvant chemotherapy, no overall benefit was seen. However, within the subgroup with pathologic stage IB–III disease, high-grade patients demonstrated a clinical trend toward benefit from adjuvant treatment. Genomic profiling in a matched subset revealed distinct patterns of PI3K pathway alterations in low-grade tumors and TP53 truncating mutations in high-grade tumors, suggesting different oncogenic drivers between tumor grades.

The authors concluded the IASLC tumor budding-based grading system independently stratified overall and disease-free survival, and was linked to divergent genomic alterations. While prospective multicenter validation is needed, these findings extend the clinical and biological significance of the new grading system for helping guide treatment decisions.