The ratio of cancer cells to stroma within the invasive area is a histologic prognostic parameter of lung adenocarcinoma.

OBJECTIVES: This study evaluated whether the proportion of cancer cells to non-cancerous stroma within the invasive area is associated with the prognosis of patients with lung adenocarcinoma.

MATERIALS AND METHODS: A total of 127 patients with lung adenocarcinomas with tumors larger than 3 cm in total size were enrolled in this study. We classified the tumors according to the ratio of area occupied by cancer cells within the invasive area (Type A: more than 50% of the invasive area, Type B: 10-50%, and Type C: less than 10%) and analyzed the clinicopathological differences between Types A, B, and C.

RESULTS: The invasive size of Type A tumors (n = 35) was significantly larger than those of the other two tumor types; however, there was no significant difference in the invasive size between Types B (n = 65) and C (n = 25) tumors. The recurrence-free survival time of patients with Type C tumors was significantly longer than those of patients with Type A and B (P < .001) tumors. Multivariate analysis revealed that Type C tumor was an independent favorable prognostic factor (P = .037) but that invasive size was not. The invasive area of Type C tumor was composed of a significantly higher proportion of collapsed elastic fibers than the invasive areas of Type A and B tumors (P < .001).

CONCLUSION: A lower cancer cell to stroma ratio within the invasive area could be a significant prognostic factor in lung adenocarcinoma, suggesting that not only the invasive size but also the invasive character might be an important histologic prognostic parameter.