The prognostic role of pathologic invasive component size, excluding lepidic growth, in stage I lung adenocarcinoma

Objectives: We performed an investigation of the prognostic significance of the invasive component size, excluding lepidic growth, in lung adenocarcinoma patients. Methods: The data from 603 patients with completely resected pathologic stage I lung adenocarcinomas were analyzed retrospectively to determine the relationship between pathologic tumor size and surgical results. Results: The median tumor size of the total growth and the invasive component were 2.2 cm and 1.3 cm, respectively. There were significant differences in recurrence-free survival between patients classified on the basis of invasive component sizes (<= 0.5 cm vs 0.5-2.0 cm, P < .001; and 0.5-2.0 cm vs > 2.0 cm; P = .026). A multivariate Cox regression analysis showed that invasive component size (P = .002), age, sex, and lymphatic invasion were independent prognostic factors for recurrence-free survival, whereas total tumor size was not (P = .068). There were no significant differences in recurrence-free survival between patients who received adjuvant chemotherapy and those who did not in the group with invasive component size of 0.5 cm or less (P = .29) and in the group with invasive component size of 0.5 to 2.0 cm (P = .50). However, the recurrence-free survival of patients who received adjuvant chemotherapy was significantly better than that of those who did not in the group with invasive component size greater than 2.0 cm (P = .009). Conclusions: Pathologic invasive component size, as opposed to total tumor size, is associated more significantly with malignant behavior and prognosis and specifically should be considered before choosing candidates for adjuvant chemotherapy in pathologic stage I lung adenocarcinoma.