Prognostic impact of pleural invasion in 1488 patients with surgically resected non-small cell lung carcinoma

Objective: This study aimed to verify the prognostic impact of pleural invasion according to the revised TNM classification, seventh edition. Methods: The study consisted of 1488 patients with surgically resected non-small cell carcinoma. The degree (pl0-3) and location of pleural invasion were examined using hematoxylin and eosin- and elastica van Gieson-stained slides, and outcome was compared with stratification by several clinicopathological factors. Results: The 5-year overall survival rates of 1008, 260, 85 and 135 patients with pl0, pl1, pl2 and pl3 tumours were 80, 60, 55 and 52%, respectively. Overall survival differed significantly between patients with pl0 tumours and those with pl1 tumours (P< 0.0001). The difference was significant for patients with 1 <≤ 2 cm (P = 0.004), 2,<≤ 3 cm (P = 0.003) and 3,<≤ 5 cm (P = 0.02) tumours. The overall survival of pl0 patients was also significantly better in patients with adenocarcinoma (P< 0.0001) than squamous cell carcinoma (P = 0.043). The overall survival of pl0 patients was significantly better in patients without lymph node metastasis (P< 0.0001) than in those with lymph node metastasis. The 5-year overall survival rates of patients with interlobar, lateral, mediastinal and diaphragmatic pl3 tumours were 65, 51, 51 and 40%, respectively. Overall survival did not differ significantly among these four groups. Conclusions: Outcome differs between patients with pl0 tumours and those with pl1-3 tumours, particularly among patients with 1 <≤ 2 cm, 2 <≤ 3 cm and 3<≤ 5 cm tumours, adenocarcinoma histology and no lymph node metastasis. The location of pl3 pleural invasion did not affect outcome significantly.