Abstract 110P
Background
Analyses reported to date on tumour infiltrating lymphocytes (TIL) have evaluated mostly stromal, possibly intratumoral TIL, but we have not found any in which TIL were evaluated spatially, by stromal and intratumoral category, separately in compartments of central tumour (CT) and invasive margin (IM).
Methods
We retrospectively analysed consecutive sample of 152 early TNBC patients treated at our institution 2009-2012. TIL were assessed by HE, using standard FFPE samples, according to International Working Group for Evaluation of TIL recommendation, both stromal TIL (sTIL) and intratumoral TIL (iTIL), spatially, in compartments of CT and IM.
Results
Spatial analysis revealed the following: overall sTIL content was in median 19%, iTIL 5%, TIL in CT 5%, at IM 18%, sTIL in CT 5%, iTIL in CT 1%, sTIL at IM 30%, and iTIL at IM 5%. Prevalence of intermediate or high TIL content, defined as ≥10% was: sTIL in CT in 48%, iTIL in CT in 23%, sTIL at IM in 86%, and iTIL at IM in 47% of cases. Quarter of patients had TIL>50% in any of the evaluated compartments. There was statistically significant correlation between sTIL and iTIL, presence of TIL in all four evaluated compartments, and correlation was stronger among sTIL and iTIL in CT, and sTIL and iTIL at IM, than between the two compartments. In bivariable analysis all TIL indicators were significantly associated with longer DFS and OS. Overall, patients with TIL≥10% in all four evaluated compartments (sTIL and iTIL, in CT and IM) were shown to have statistically significantly better DFS and OS, compared to those with TIL<10%. After adjustment for potential confounders using Cox proportional hazard regression, significant predictors of OS were sTIL (p0.007), iTIL if present in ≥10% (p0.022), TIL at IM (p0.002), sTIL at IM (p0.001), and iTIL at IM if present in ≥10% (p0.036).
Conclusions
Compartmental morphological analysis of TIL reveals frequent intermediate to high density of TIL content on IM and their overall statistically significant prognostic impact. This draws attention to this neglected tumoral compartment and directs the question towards the different biology, cell composition, and role of each tumour morphological compartment, a phenomenon that should definitely be further explored.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.