Prognostic impact of uncertain parietal pleural invasion at adhesion sites in non-small cell lung cancer patients

Objectives: Pleural invasion has been recognized as an important negative prognostic factor in non-small cell lung cancer (NSCLC), and therefore, accurate evaluation is required. However, when the visceral pleura adheres to the parietal pleura around a tumor and parietal pleural structures are destroyed and unrecognizable as a result of inflammation, it is often difficult to accurately evaluate pleural invasion, and classification of the T stage is unclear. To aid in categorization, we defined this status as pl1-3 and investigated the prognostic impact of the pl1-3 status on NSCLC. Materials and methods: We retrospectively examined the clinicopathological characteristics and prognoses of 929 NSCLC patients who underwent curative surgical resection. The p1-3 status was defined as invasion beyond the elastic layer of the visceral pleura (pl1 or higher) but showing unclear parietal pleural invasion. We compared the prognoses of pl1-3 status NSCLC patients with that of patients with other pleural invasion statuses. Results: Thirty-one patients (3%) had a pl1-3 status. The 5-year overall survival rate for pl1-3 patients was 58.9%, and the prognosis was significantly worse than pl1 (p = 0.04). In pN0 cohort, pl1-3 disease had a significantly worse prognosis than pl1 and pI2 diseases (p = 0.01 and 0.04, respectively) and a similar prognosis to pl3 disease. Furthermore, similar relationships were also observed after adjusting for other prognostic factors in multivariate analysis. Among the pl1-3 and pN0 patients, 11 (46%) developed recurrences (9 patients had distant metastasis, one had local recurrence, and one had both). Although the proportion of pl1-3 patients who underwent adjuvant therapy was similar to that of T3 patients, more individuals received oral tegafur-uracil treatment than intravenous chemotherapy. Conclusion: These results indicate that pl1-3 patients can be managed in the same manner as patients with T3 and pl3 disease. These results may be informative for treatment decisions during postoperative chemotherapy. (C) 2017 Elsevier B.V. All rights reserved.