Abstract P4-02-10: Are fine-needle aspiration (FNA)-derived cell blocks a useful tissue sample surrogate for testing conventional biomarkers and PD-L1 in breast cancer?
Authors: Bravaccini S , Ravaioli S , Rocca A , Tumedei MM , Bucchi E , Malmesi M , Medri L , Bonafè M , Puccetti M 
Published: May 2019

Background The diagnosis of breast cancer (BC) is based on clinical examination in combination with imaging and confirmed by pathological assessment of core needle biopsy (CNB) or fine needle aspiration (FNA). The biological profile of the lesion is needed to define prognosis and guide therapy. Given the importance of an early and minimally invasive diagnosis, we aimed to verify whether the biological features detected in FNA-derived cytological material reflect the biological characteristics of surgical specimens.

Methods We used immunohistochemistry and fluorescence in situ hybridization (FISH) to study a panel of biomarkers (ER, PgR, Ki67 and HER2 in 93 patients, programmed death-ligand 1 (PD-L1) in 20 patients) in FNA-derived cell blocks of BC, comparing the results with those obtained on the histological specimens.Immunostaining was performed with the Ventana Benchmark XT system and the Ultraview DAB Detection Kit (Ventana Medical Systems). Confirm anti-ER (clone SP1, Ventana), Confirm Anti-PgR (clone 1E2, Ventana) and Ki67 (clone Mib-1, Dako, Carpinteria, CA, US) antibodies were used. Ventana PD-L1 (SP263) assay (Ventana Medical Systems) was used for PD-L1 immunostaining. HER2 status was analyzed by FISH using PathVysion kit (Abbott Molecular, Abbott Park, Illinois, IL, USA).

Results Median immunopositive values of ER, PgR Ki67, and PD-L1 were similar in cell blocks and surgical samples. Concordance for ER and PgR between FNA and histological samples was 98% and 84%, respectively. With regard to Ki67 and HER2 status, concordance between the two specimen types was 90% and 96%, respectively. PD-L1 expression analyzed in FNA-derived samples was 100% concordant with that of surgical specimens. Tumor subtype classification for triple-negative and HER2-positive tumors in FNA samples was always concordant with the subtype determined in surgical material.

Table 1.Concordance of tumor subtype classification between FNAB-derived and histological samples.Overall series (n=93)87%Luminal A (n=26)81%Luminal B (n=47)86%HER2-positive (n=6)100%Triple-negative (n=14)100%

Conclusions We showed that biological marker determination in FNA-derived cell blocks is feasible and provides useful information and comparable results with those obtained by histological evaluation. Given the low cost of the procedure and its minimal impact on patients, that cytological samples could be used as an alternative to tissue samples for early BC biomarker evaluation to facilitate the planning of tailored neoadjuvant therapy.

Citation Format: Bravaccini S, Ravaioli S, Rocca A, Tumedei MM, Bucchi E, Malmesi M, Medri L, Bonafè M, Puccetti M. Are fine-needle aspiration (FNA)-derived cell blocks a useful tissue sample surrogate for testing conventional biomarkers and PD-L1 in breast cancer? [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-02-10.