Does tumor stroma ratio of breast cancer trucut biopsy determine response to neoadjuvant therapy?

We examined the prognostic value of Tumor stroma ratio (TSR) in breast tumor core biopsy (TCB) specimen to determine response to neoadjuvant therapy (NAT) prior to modified radical mastectomy (MRM).This was a retrospective analysis of patients with breast cancer who underwent TCB before NAT between August 2016 and July 2018. TSR in TCB was studied independently by 2 pathologists ( VM, VS) defined as stroma rich (TSR≤50%) or stroma poor (TSR>50%). MRM specimen of these patients were subsequently studied .Residual cancer burden (RCB) was calculated using the MD Anderson RCB calculator, categorized as complete (0), good (1) Partial (2) and no response (3). Statistical analysis was done to assess correlation of TSR to RCB.A total of 62 patients were analyzed. Mean(SD) age was 48(11) years.Twenty eight (45%) and 34 (55%) patients were stroma rich and stroma poor respectively. Twenty six (42%) patients were responders and 36 (58%) non-responders to NAT. Among stroma rich patients, only 3 (10%) were responders (Class 0 &1)and 25 (90%) non-responders(Class2&3)to NAT, among stroma poor patients 23 (68%) responded well and 11 (32%) did not.TSR had a moderate negative correlation with RCB (-0.6). On univariate analysis, only TSR had a significant effect on RCB class (<0.001).TSR on TCB is a useful prognostic factor to determine response of breast carcinoma patients to neoadjuvant therapy.It is cost effective, simple and quick. Larger multi-centric studies would be useful to study its clinical implications.