Abstract P2-11-27: Peritumoral desmoplasia in breast cancer – does it matter?
Authors: Weydandt Laura , Wolf Benjamin , Horn Lars-Christian , Aktas Bahriye 
Published: March 2023

Abstract
Background: The peritumoral deposition of collagen is termed desmoplasia. It is characterized by the formation of new extracellular matrix, resulting from activation of tumor-associated fibroblasts. In other cancer entities (e.g. pancreatic and thyroid cancer), the presence of desmoplasia has significant prognostic impact. Furthermore, in preclinical models, targeting desmoplasia therapeutically to normalize the microenvironment has shown promising results. Yet, the role of desmoplasia in breast cancer is still unclear and data regarding this topic is rare. The aim of this study is to investigate whether desmoplasia is present in breast cancer and whether it is associated with other prognostic factors. Methods: We retrospectively analyzed 361 patients with breast cancer who had oncologic surgery at the University Hospital Leipzig, Germany between 2015 and 2018. Patients underwent operation without any preoperative therapy, after neoadjuvant chemotherapy, or after neoadjuvant endocrine treatment. One patient had had radiation in the past. Information regarding desmoplastic tumor reaction and other pathologic characteristics were retrospectively retrieved from the pathology reports. Results: Overall, data regarding desmoplasia was available for 197 patients. Median patient age was 61 years [IQR 50-73] with the most frequent tumor entity (62.9%) being invasive carcinoma of no special type (NST). 184 (93.4%) patients had either a T1 or T2 stadium. Patients had no preoperative therapy, neoadjuvant chemotherapy, or neoadjuvant endocrine treatment in 131 (66.5%), 36 (18.3%) and 29 (14.7%) cases, respectively. Desmoplasia was present in 151 cases. 46 cases showed no evidence for desmoplasia. Median age was almost similar in both groups (60.5 years vs. 61 years). Presence of desmoplasia was not associated with lymph node metastasis (pN1: 26.1% in patients with desmoplasia vs. 31.1% in patients without desmoplasia). Furthermore, there were only small differences in tumor grade between the two groups (G1: 45.7%, G2: 37.8%, G3: 15.9% [patients with desmoplasia] vs. G1: 39.1%, G2: 43.5%, G3: 17.4% [patients with no desmoplasia]. Tumor stages pT1 and pT2 were approximately equal in the two groups (pT1: 66.2% vs. 65.2%, pT2: 29.1% vs. 21.7%). There was a slight trend towards a higher (pT3) tumor stage in patients with desmoplasia (13%) compared to the patients with no desmoplasia (2.7%). Interestingly, the presence of desmoplasia was significantly associated with a higher number of Luminal A subtypes (64.2% vs. 47.8%, p-value: 0.047) and a lower number of triple negative carcinoma (10.6% vs. 17.4%. p-value: 0.22). Conclusions: In our analysis, the presence of desmoplasia is not associated with a more aggressive phenotype of breast cancer. There are hints for an association with a favorable subtype. Larger studies are necessary to validate these data and gain further information.
Citation Format: Laura Weydandt, Benjamin Wolf, Lars-Christian Horn, Bahriye Aktas. Peritumoral desmoplasia in breast cancer – does it matter? [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-27.