Clinicopathologic study of stage I adenosquamous carcinoma of the lung

Adenosquamous carcinoma of the lung is a characteristic tumor that has both adenocarcinoma and squamous cell carcinoma components. Adenosquamous carcinoma is reported to have an aggressive clinical course, but its clinicopathological features and prognosis are unclear in the early stage.

Patients who underwent surgical resection for pathological stage I non-small cell lung cancer between April 2009 and December 2014 were retrospectively reviewed. Preoperative and postoperative data, histologic characteristics and outcomes of patients with adenosquamous carcinoma (n = 40) were compared to adenocarcinoma (n = 598) and squamous cell carcinoma (n = 131) patients. Factors affecting prognosis, particularly on recurrence, were assessed via Cox regression analyses.

Patients with adenosquamous carcinoma had a worse prognosis than did patients with adenocarcinoma and squamous cell carcinoma in terms of 5 year overall (66.7%) and recurrence-free survival rates (44.9%), as well as a significantly higher recurrence rate (13/40 patients, 32.5%). Multivariable Cox regression analysis for recurrence-free survival rates revealed that the histology of adenosquamous carcinoma was an independent factor for recurrence (hazard ratio: 2.473, 95% confidence interval: 1.328-3.367; P = 0.0004). High serum carcinoembryonic antigen levels (hazard ratio: 5.962) and vascular invasion (hazard ratio: 4.899) were identified as risk factors for recurrence, and patients with adenosquamous carcinoma tended to have distant relapses, such as in the brain.

Early-stage adenosquamous carcinoma of the lung is a histological type associated with severe prognosis and postoperative recurrence, often in distant sites, in approximately one-third of cases. High serum carcinoembryonic antigen levels and vascular invasion might be risk factors of recurrence.