The Distribution and Prognostic Significance of Tumour Infiltrating Lymphocytes in Invasive Breast Carcinoma of Egyptian Patients

Author(s): Amera M Sheha, Fatma Badary, Tarek Mohamed Elsaba, Michael S Toss

Background: The relationship between tumour infiltrating lymphocytes (TILs) and racial background in invasive breast carcinoma (IBC) is not well studied. In this study, we assessed the association between TILs and various clinicopathological parameters and outcome in a cohort of Egyptian IBC patients.

Methods: This study included a retrospective cohort (n=184) of IBC diagnosed in South Egypt Cancer Institute. All haematoxylin and eosin (H&E) histological sections were retrieved and the percentage of stromal TILs was assessed by 3 pathologists. The interobserver concordance was assessed and the association between TILs and clinicopathological factors and patients’ outcome was analysed.

Results: There was an excellent interobserver concordance for TILs assessment (Inter-cluster correlation coefficient ICC=0.9). 70% of the cohort showed TILs density >10%. TILs score was higher in patients aged less than 50 years (p=0.004), higher tumour grade (p=0.001), no special type and special types of breast carcinoma (p=0.001), and hormonal receptor negativity (p=0.001).Triple negative breast cancer (TNBC) and HER2 enriched molecular subtypes showed the highest TILs density among the molecular classes (p=0.018).There was no significant association between TILs and outcome.

Conclusion: Our study revealed that TILs are associated with features of high-risk IBC. Although the distribution of TILs among various IBC characteristics in Egyptian patients was similar to other ethnicities, there was no association between TILs density and patient outcome. Further epidemiological and comparative studies are warranted.