Impact of Solid Minor Histologic Subtype in Postsurgical Prognosis of Stage I Lung Adenocarcinoma.

BACKGROUND: Few studies focus on the outcome and effect of a postsurgical treatment strategy for early stage patients with minor solid components pattern. This study investigated the prognosis and the adjuvant chemotherapy benefit among stage I invasive lung adenocarcinoma patients with minor solid components pattern according to the eighth TNM staging classification.

METHODS: A total of 3,308 lung adenocarcinoma patients with mixed histologic components was divided into three groups: solid predominant, solid minor, and solid absent pattern. Disease-free survival and overall survival were analyzed to evaluate survival difference among patients in the different groups using the Kaplan-Meier approach and multivariable Cox models.

RESULTS: Both solid predominant and solid minor groups showed significantly worse disease-free survival (p < 0.001) and overall survival (p < 0.001) compared with the solid absent group. There were no significant disease-free survival (hazard ratio [HR] 1.41, 95% confidence interval [CI]: 0.87 to 2.30, p = 0.161) or overall survival (HR 1.60, 95% CI: 0.83 to 3.09, p = 0.159) difference between the former two groups. For patients in stage IB, adjuvant chemotherapy improves disease-free survival (HR 0.33, 95% CI: 0.11 to 1.02, p = 0.044) but not overall survival (HR 0.61, 95% CI: 0.21 to 1.77, p = 0.360) in the solid predominant group. No adjuvant chemotherapy benefits for disease-free survival (HR 1.04, 95% CI: 0.49 to 2.22; p = 0.922) and overall survival (HR 0.49, 95% CI: 0.13 to 1.90; p = 0.291) were seen for the solid minor group.

CONCLUSIONS: Solid minor components predict a significantly worse prognosis compared with the solid absent pattern. However, adjuvant chemotherapy may be unhelpful to improve outcomes for stage IB patients with solid minor components after surgery.