Objective. The inflammation is known to be essential in the neoplastic progression, nevertheless this host-tumor interaction has not been yet clarified. Whilst neoangiogenesis might stimulate the tumor progression, simultaneously this process could interfere with tumor growth. The aim of this study was to evaluate the prognostic value of intra- and peri- tumor infiltrating lymphocites (TILs) and correlate this parameter with the overall survival.
Material and Methods. We retrospectively collected 50 cases of epithelioid pleural mesthelioma analyzed from 2005 until 2016 by UCO di Anatomia e Istologia Patologica di Trieste. Immunohistochemistry staining of CD3 was performed to define intra-tumor lymphocites count. Intraepithelial, stromal and peritumoral TILs was assessed using the following scoring system: score 1 when TILs percentage ranges between 6 and 25%; score 2 when TILs percentage ranges between 26 and 50% and score 3 between 51% and 75%. Data were statistically analyzed by Kaplan-Meier method using a dedicated software (Statistical Package for Social Sciences, SPSS Inc., Chicago, IL, USA). The level of significance was p < 0.05.
Results. In this sample the average and median age were 70 and 71 respectively. The 4-years OS was 16% (n=8) with 42 deaths due to mesothelioma and the event occurred after an average period 14.97 months long. Neither intraepithelial nor stromal TILs scores correlated with OS (p>0.05). On the contrary, high scores (2+3 score) of peritumoral TILs significantly correlates with improved OS (p=0.02).
Conclusions. In our experience, peritumoral TILs was a positive prognostic factor in epithelioid pleural mesothelioma. This result suggests to include an immunological analysis in the therapeutical approach to mesothelioma because it has to be clarify how immune elements take part in the tumor progression. Aiming to stimulate a specific antitumor immune response,further studies are needed to optimize the immunotherapy
