36 Chapter 3 Abstract Aims The aim of this study was to determine the relationship between proliferative activity, PD-L1 status and nuclear size changes after pre-operative chemo-radiotherapy (CRT) and clinical outcome in patients with superior sulcus tumours. Methods Proliferative activity (MIB-1) and PD-L1 status was estimated by immunohistochemistry in the tumour cells of resection specimen in a series of 33 patients with residual tumour after tri-modality therapy for a sulcus superior tumour between 2005 and 2014. A morphometric analysis of both pre- and post-treatment tumour material was also performed. Results were related to disease free survival (DFS) and overall survival (OS). Results Low proliferative activity (<20% MIB-1) was associated with better OS: 2-year OS of 73% compared to 43% and 25%, respectively for moderate (MIB-1 20-50%) and high proliferative activity (MIB-1 >50%) (p=0.016). A negative PD-L1 status (<1% positive tumour cells) was also associated with a better OS (p=0.021). The mean nuclear size of normal lung tissue pneumocytes was significantly smaller compared to the mean nuclear size of tumour cells of the resection specimens (median difference -38.1; range -115.2 - 16.0; p<0.001). Mean nuclear size of tumour cells did not differ between pre-treatment biopsies and resection specimens (median difference -4.6; range -75.2 - 86.7; p=0.14). Nuclear size was not associated with survival (p= 0.82). Conclusions Low proliferative activity determined by MIB-1 as well as a negative PDL-1 expression are significantly associated with a better overall survival in patients with residual tumour after CRT for superior sulcus tumour.
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