78P Multiplex immunohistochemistry and digital pathology analysis examining the prevalence and prognostic value of tertiary lymphoid structures in early stage hormone positive, HER2-negative breast cancer

Tertiary lymphoid structures (TLS) are ectopic organs that arise in nonlymphoid tissue sites of chronic inflammation including tumours. The presence TLS, has been associated with increased tumour antigen presentation and improved cytokine-mediated signalling activity against cells. Due to this, TLS have favourable outcomes a number cancer types. There is limited data regarding the prevalence prognostic implication hormone positive, HER2-negative (ER+/HER2-) breast cancer. Formalin-fixed paraffin embedded blocks from cohort 429 patients early stage positive/ were used construct TMA three x 1 mm cores per patient. Multiplex chromogenic immunohistochemistry staining was performed stain for CD3+ T cells, CD20+ B cells DCLamp + dendritic Digital image analysis using Qupath open source software. On basis panel, samples could broadly be divided into categories; immune cold minimal infiltrate, T-cell only infiltrate defined by seen 14% (n=60) patient which similar rate significant also (n=60). majority had no comprising 72% (n=312) cohort. median cells/mm2 entire 295mm2. When these categories, there statistically difference disease free survival (p value= 0.39) although trend towards worse those high infiltrate. In contrast other subtypes, infiltrating lymphocytes ER+/HER2- may poor prognositc feature. However this dependant on subpopulation perhaps differing Further research larger cohorts would required investigate further.