Abstract 194P
Background
Neoadjuvant systemic therapy (NAST) is increasingly being used to treat locally advanced breast cancer with the goal of less extensive surgery of the breast and axilla. The best possible outcome of NAST is complete pathological response (pCR) in both sites. A high density of tumor-infiltrating lymphocytes (TIL) is prognostic for pCR to NAST in some histologic subtypes. The aim of our study was to prospectively assess TIL and pCR correlation on core needle biopsy (CNB) samples in patients before NAST.
Methods
A prospective observational study on early breast cancer patients stage IIA–IIIB. Patients with all histologic subtypes, except for luminal-A-like, proceeded with NAST. On CNB samples stained with haematoxylin-eosin, we performed a TIL density assessment, expressed as the percentage of area of intratumoral stroma covered by lymphocytes (as per International TIL Working Group recommendations in 2014). pCR was defined as complete remission in breast and in axillary nodes. We used univariate linear regression to calculate the above noted correlation values. We also determined the optimal TIL cutoff value, which showed the best differentiation between the two outcome groups when used to segregate our patients into low TIL and high TIL subgroups. For that, we performed a chi-square test using TIL cutoff values from 0 to 100 in increments of 1.
Results
We enrolled 141 patients. Our patient population consisted of: 18 her2+ (89% pCR), 2 luminal A (no pCR), 65 luminal B (11% pCR), 35 triple- (51% pCR) and 21 triple+ (43% pCR). The TIL values in pCR and no-pCR groups were shown to be statistically significantly different, with a p-value of <0.001 and a standard error of 0.0017. The distribution of TIL values in the two groups was: mean and stdev 28.12(±26.15), median 20 for the pCR group, and mean and stdev 10.33(±15.12), median 5 for the no-pCR group. The optimal TIL cutoff value in our patients was 10 (p 0.00003).
Conclusions
Our results show that higher TIL scores correlate with higher pCR outcomes, which is congruent to the results thus far observed in the available literature. This also hints at our TIL scoring quality being good.
Clinical trial identification
EudraCT 2018-000547-11.
Editorial acknowledgement
Legal entity responsible for the study
Cvetka Grašič Kuhar.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.