Factors associated with long term freedom from recurrence after induction chemotherapy and extrapleural pneumonectomy in mesothelioma patient

Hintergrund: Treatment outcomes following multimodality treatment of mesothelioma are variable. There are patients with exceptionally long freedom from recurrence (FFR) following multimodality treatment consisting of induction chemotherapy followed by extrapleural pneumonectomy (EPP). We aimed to determine clinical and biological prognostic factors associated with long term freedom of recurrence (3 years).

Material und Methode: Between September 1999 and July 2009 93 patients with malignant pleural mesothelioma (MPM) were treated with induction chemotherapy and extrapleural pneumonectomy. They were stratified into 2 groups: freedom from recurrence (FFR) less than 36 months (n = 81) and FFR of 36 months and longer (n = 12). Proliferation index (Ki-67 and Survivin) in the surgical specimen as well as clinical factors were analyzed using Mann-Whitney U test for continuous variables and Fisher's exact test for categorical variables.

Ergebnis: Age at surgery was significantly higher in patients with long term FFR (median age 66 years vs. 60 years; p = 0.001) and there were significantly more women in the long term FFR group (33% vs. 6%, p = 0.02). IMIG stage was lower in the long term FFR group, with none of the long FFR patients being IMIG stage IV.

Ki-67 and Survivin staining index (p = 0.02 and 0.001, respectively) were significantly lower in the tumor tissue of patients with long term FFR.

Schlussfolgerung: Our analyses demonstrated that older age, female gender, low IMIG stage and low tumor proliferation index are associated with long FFR after multimodality treatment. This study shows that biological differences exist between patients with long and short FFR, which could be the underlying reason for these differences in FFR and warrant further investigation.