Invasive area to tumor ratio is a significant prognostic factor for non‐small cell lung cancer

BACKGROUND: Although T factor is defined as the size of invasive area rather than total tumor size in the eighth edition of the TNM classification, whether the pathological invasive area to tumor ratio (ITR) is a prognostic factor has not yet been evaluated. METHODS: In total, 432 lung adenocarcinoma patients were analyzed, among which 266 patients with pathological stage IA were used to perform a subanalysis. RESULTS: Smoking status (odds ratio [OR]: 0.43, p = 0.01), neutrophil‐to‐lymphocyte ratio (NLR) (OR: 1.97, p = 0.03), maximum standardized uptake value (SUV(max)) (OR: 3.62, p < 0.01), and ITR (OR: 6.76, p < 0.01) were significantly different in univariate analysis. Smoking status (OR: 0.34, p < 0.01), SUV(max) (OR: 3.05, p < 0.01), and ITR (OR: 5.44, p < 0.01) were risk factors for recurrence in multivariate analysis. In patients with pathological stage IA disease, smoking status (OR: 0.34, p = 0.03), NLR (OR: 2.30, p = 0.04), SUV(max) (OR: 3.63, p < 0.01), pathological invasive area (OR: 4.00, p < 0.01), and ITR (OR: 6.03, p < 0.01) were significantly different in univariate analysis. Smoking status (OR: 0.27, p = 0.02), SUV(max) (OR: 3.93, p < 0.01), and ITR (OR: 4.38, p < 0.01) were significant risk factors for recurrence in multivariate analysis. CONCLUSIONS: SUV(max) and ITR are risk factors for recurrence. These results suggest that SUV(max) is important for deciding the indication for limited resection or adjuvant chemotherapy, and ITR is an adaptation criterion for adjuvant chemotherapy for early‐stage lung adenocarcinoma patients.