Predictive Value of Recurrence of Solid and Micropapillary Subtypes in Lung Adenocarcinoma.

Introduction: Although histological subtype in lung adenocarcinoma has been reported as a poor prognostic factor in several studies, its utility has not yet been revealed as an adaptation criterion of postoperative adjuvant chemotherapy.

Methods: Four hundred ninety-four lung adenocarcinoma patients were enrolled in this retrospective study. A subanalysis was performed in 420 lung adenocarcinoma patients with pathological stage 0-I disease for risk factors of postoperative recurrence.

Results: Maximum standardized uptake value (SUVmax) (p < 0.01), pathological stage ≥II (p < 0.04), and adjuvant chemotherapy (p < 0.01) were risk factors for recurrence in the multivariate analysis, whereas histological subtype was not a significant factor for recurrence at all stages. In the subanalysis, univariate analysis showed that carcinoembryonic antigen expression (p < 0.01), prognostic nutrition index (p = 0.03), SUVmax (p < 0.01), lymphatic invasion (p < 0.01), vascular invasion (p < 0.01), grade 3-4 differentiation (p < 0.01), pathological stage ≥IA3 (p < 0.01), and histological subtype (p = 0.03) were significant risk factors of recurrence. SUVmax (p < 0.01) was the only risk factor for recurrence in the multivariate analysis, whereas histological subtype was not (p = 0.07). Relapse-free survival (RFS) was significantly worse in the micropapillary- and solid-predominant subtype groups than in the other subtypes (p = 0.01). On the other hand, RFS with or without uracil-tegafur as adjuvant chemotherapy in lung micropapillary- or solid-predominant adenocarcinoma patients with pathological stage IA-IB disease was not significantly different.

Conclusion: This study suggested that histological subtypes, such as micropapillary- or solid-predominant pattern, are risk factors for recurrence in pathological stage 0-I lung adenocarcinoma and may be necessary adjuvant chemotherapy instead of uracil-tegafur.