Background: Adenocarcinoma (AC) is the most common lung cancer, followed by squamous cell carcinoma (SCC). Controversy exists concerning both cell types. Our purpose was to compare their prognosis after resection and determine whether AC subtyping may have any significance.
Methods: From 1993 to 2002, 574 patients with SCC and 565 with AC underwent a curative resection and were compared according to sex, age, type of resection, TNM system classification, and survival. One hundred fifty-nine patients with ACs demonstrated a pure histologic pattern according to the 1999 World Health Organization classification, and 406 were of the mixed subtype including cell types with potentially different aggressiveness. Therefore, we compared subgroups according to presence or not of bronchioloalveolar carcinoma or solid adenocarcinoma with mucin component, or both.
Results: Compared with ACs, SCCs had a higher number of males and older patients, and incidences of endobronchial tumors, pneumonectomies, and stage II tumors were higher. Global survival rates were not different. The ACs with solid AC with mucin components (n = 239) were characterized by more males and stage IIB patients, and had poorer survival rates (38.6% vs 61.4%; p < 0.0014) than the ACs without solid AC with mucin component. When comparing these with SCCs, 5-year survival rates were: ACs without solid AC with mucin component (58.1%), SCCs (50.2%), and ACs with solid AC with mucin component (36.8%) (p < 0.000019). Multivariate analysis demonstrated these subgroups and SCCs to be independent factors of prognosis.
Conclusions: Solid ACs with a mucin component demonstrated the poorest prognosis after resection. Further studies of this cell type, which should be looked for carefully, may help improve targetting adjuvant therapies.