Prognostic significance of a solid component in pulmonary adenocarcinoma

We retrospectively analyzed pulmonary adenocarcinoma patient survival in our single-institution database to evaluate the impact of solid adenocarcinoma components (SAC) on survival and to propose a method of incorporating SAC into the T classification in future staging systems.

We reviewed 504 consecutive patients with surgically resected pulmonary adenocarcinoma for their clinicopathologic characteristics and prognoses, stratifying patients according to predominant adenocarcinoma subtype. We also stratified patients with an SAC-containing tumor according to the ratio of SAC in analyzing outcome.

Patients with SAC (SAC+) had significantly poorer prognoses than patients without any SAC (SAC-), irrespective of SAC ratio. Patient groups stratified by pathologic T classification up to T2b could be divided into four categories according to SAC status in decreasing order of survival: (I) T1a/SAC-; (II) T1b/SAC-; (III) T1a/SAC+, T1b/SAC+, and T2a/SAC-; and (IV) T2a/SAC+ and T2b/SAC-.

Pulmonary adenocarcinoma patients with any amount of SAC had worse prognoses than those without any SAC. The presence of SAC was an independent unfavorable prognostic factor, comparable to other pathologic findings indicating invasion. Solid adenocarcinoma component was an upstaging factor in T classification for T1 and T2a pulmonary adenocarcinomas. If SAC is present, we propose T1 and T2a tumors should be classified as T2a and T2b, respectively.