Clinicopathological characteristics and prognosis of resectable lung adenosquamous carcinoma: a population-based study of the SEER database

Objective Adenosquamous carcinoma is a rare subtype of non-small cell lung cancer characterized by aggressive behavior, with combination of adenocarcinoma and squamous cell carcinoma components. The clinicopathological characteristics and prognosis of resectable adenosquamous carcinoma are incompletely understood and this study aimed to depict those in a large population. Methods A total of 805 adenosquamous carcinoma, 7875 squamous cell carcinoma and 23 957 adenocarcinoma patients who underwent lobectomy or sublobectomy were queried from the Surveillance, Epidemiology, and End Results database (2010-17). Clinicopathological characteristics of adenosquamous carcinoma patients were compared with those of squamous cell carcinoma and adenocarcinoma patients. Prognostic factors were identified by univariable and multivariable Cox regression analyses. Propensity score matching was applied to reduce confounding effects. Results Adenosquamous carcinoma was associated with higher pleural invasion incidence and poorer differentiation compared with squamous cell carcinoma or adenocarcinoma (P values < 0.001). The independent risk factors of cancer-specific survival of adenosquamous carcinoma patients were increasing age, male sex, invading through visceral pleura, poor differentiation and higher stage. Stage IB adenosquamous carcinoma patients whose tumor invaded through visceral pleura had significantly worse survival than those not (P = 0.003). Adenosquamous carcinoma patients had worse survival compared with squamous cell carcinoma (5-year-survival: 64.55 vs. 69.09%, P = 0.003) and adenocarcinoma (5-year-survival: 64.55 vs. 76.79%, P < 0.001) patients before match. And this difference persisted after match. Conclusions Resectable adenosquamous carcinoma patients had higher pleural invasion incidence, poorer differentiation and worse survival compared with squamous cell carcinoma and adenocarcinoma patients. Visceral pleural invasion status and differentiation grade were vital prognostic factors of adenosquamous carcinoma patients on the basis of stage. Resectable adenosquamous carcinoma patients had higher pleural invasion incidence, poorer differentiation and worse survival than squamous cell carcinoma and adenocarcinoma patients. Visceral pleural invasion status discriminates the survival of IB adenosquamous carcinoma patients well.