ECP 2023 Abstracts

S161 Virchows Archiv (2023) 483 (Suppl 1):S1–S391 13 investigating the possibility of active surveillance for the manage- ment of low-risk DCIS, and the biopsy method is a crucial factor to be considered in risk stratification. E-PS-02-032 Comparison of two sentinel node imaging methods magtrace and scintigraphy P. Hurník*, J. Strakos, J. Palica, Z. Vavrova, R. Ondrussek, F. Fak- houri, P. Vazan, P. Delongova, V. Zidlik, D. Ziak *University Hospital of Ostrava, Czech Republic Background & objectives: Imaging and excision of the sentinel lymph node is now a standard examination for the staging of breast tumours and melanomas. This examination can be performed using staining methods, scintigraphy and Magtrace. Methods: This study compares a total of 320 patients who under- went breast cancer surgery including sentinel lymph node biopsy. In 3/21-3/22, 165 patients were screened with Tc99, and in 4/22-3/23, 155 patients were screened with an iron-based tracer (Magtrace). Pri- mary results emphasized the number of examined nodes, the number and quality of metastases and pT status with evaluation of receptor expression. Results: In the case of Tc99 scintigraphic examination, a total of 527 sentinel lymph nodes were examined in 165 patients with an average of 3.19 SLN per patient. Node positivity was detected in 44 SLNs (8.34%) - of which ITC in 6.8%, micrometastasis in 45.45%, macrometasta- sis was confirmed in 47.72%. A total of 616 nodes from 155 patients were examined using the MAGtrace method, with an average of 3.97 SLN per patient. Node positivity was detected in 59 SLN (9.57%) - of which ITC in 5.08%, micrometastasis in 40.67%, macrometastasis was confirmed in 54.23%. Of course, other statistical analyses were also carried out. Conclusion: Magtrace is safe to use method and it has significantly increased the detection rate of positive sentinel lymph nodes in our department. It has also improved the quality of care. A significant reduction in preoperative care and a positive impact on operative time have also been reported in the literature. It has therefore helped to reduce costs and improve patient comfort when introduced. E-PS-02-033 Metastatic uterine leiomyosarcoma presenting as a symptomatic breast lump: a case report N. Ibišević*, A. Humackic, Z. Guzin, K. Tomic, B. Lukic, S. Vranic *Clinical Center University of Sarajevo, Bosnia and Herzegovina Background & objectives: Metastatic solid tumours in the breast account for ~1% of all breast malignancies. The most common meta- static tumours in the breast are hematologic malignancies, melanoma, lung, ovarian, and gastric cancers. Metastatic sarcomas, particularly symptomatic, are very rare. Methods: We present a rare case of symptomatic metastatic uterine lei- omyosarcoma to the breast. The patient had a history (six years ago) of a hysterectomy and bilateral salpingo-oophorectomy for multiple uter- ine fibroids, one of which was diagnosed as a symplastic leiomyoma. Results: A 55-year-old woman clinically presented with a painless, palpable left breast mass measuring 20 mm. A core biopsy of the breast mass demonstrated a cellular spindle cell neoplasm, suggesting a smooth muscle neoplasm suspected to be malignant (B4). A wide local excision of the breast mass was performed, revealing grade 2 leiomyosarcoma. Re-review of the uterine fibroids revealed the larg- est one (200x130 mm) to be morphologically identical to the breast lesion. Additional diagnostic work-up revealed multiple liver and pulmonary metastases with a suspected metastatic sclerotic lesion in the L3 projection. The patient was subsequently treated with chemo- therapy protocol for metastatic leiomyosarcoma (ongoing). Conclusion: Metastatic tumours in the breast are rare, particularly symptomatic and of soft tissue origins, such as leiomyosarcoma. How- ever, they may be more frequently seen in patients with advanced/ widespread metastatic disease. E-PS-02-034 Prognostic implications of histopathological evaluation in post- neoadjuvant chemotherapy breast cancer patients: our experience M. Iuzzolino*, C. De Carlo, D. Gentile, A. Sagona, E. Barbieri, S. Di Maria Grimaldi, R.M. Trimboli, D. Bernardi, S. Darwish, C. Tinterri, L.M. Terracciano, B. Fernandes *Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Milan, Italy; Department of Pathology, IRCCS Humanitas Research Hospital, Rozzano, Italy Background & objectives: Breast cancer (BC) response to neoad- juvant chemotherapy (NAC) is linked to long-term outcomes. In this study, we intend to correlate post-NAC histological measures [resid- ual tumour cellularity (RTC) and pathologic complete (pCR)/partial response (pPR)] and residual disease pattern to patient prognosis. Methods: Consecutive BC cases undergoing NAC in our Institu- tion between 2006 and 2020 were reviewed. We evaluated post-NAC tumour dimension, sub-type, histotype and vascular invasion. For patients with pPR, the percentage of RTC was calculated. We assessed residual disease pattern, dividing it into scattered or circumscribed. Results were correlated to disease-free survival (DFS), distant disease- free survival (DDFS), and overall survival (OS). Results: Overall, 495 patients were analysed. The majority of patients undergoing NAC were affected by HER2-positive BC sub-type (40.4%). 148 (29.9%) achieved pCR, 347 (70.1%) had pPR, and the median RTC was 40%. Pattern of residual disease was recorded as circumscribed in 195 (56.2%) cases, scattered in 152 (43.8%) cases. At multivari- able analysis, two independent factors predicting pCR were identified: BC sub-type (HER2-positive 54.7% versus triple-negative 29.8% ver- sus luminal-like 15.5%) and vascular invasion (absence 98.0% versus presence 2.0%). We found statistically significant longer DFS, DDFS, and OS in patients with pCR and with RTC <40%; no difference was observed in terms of OS between RTC <40% and RTC ≥40% groups. Conclusion: Patients with BC treated with NAC and subsequent surgery who achieve pCR have better long-term oncological results in terms of DFS, DDFS, and OS compared to patients with pPR. BC sub-type and vascular invasion are significantly and independently associated with pCR. Measurement of RTC in BC patients improves the prognostic infor- mation that can be obtained from the assessment of pathologic response. We are conducting further statistical studies to correlate residual disease pattern (scattered versus circumscribed) to prognosis. E-PS-02-035 HER2 expression is sensitive to intratumoral hypoxia in HER2-low invasive breast carcinoma P. Juhasz*, G. Mehes *University of Debrecen, Hungary Background & objectives: Heterogeneity of HER2 expression is com- mon in HER2-low invasive breast carcinoma (BC). Carbonic anhydra- seIX (CAIX) is upregulated in hypoxic tumour cells with an adverse prognostic effect in BC. The relation of CAIX to intratumoral HER2 and microvessel distribution was evaluated. Methods: Altogether 60 HER2 non-amplified BC samples with 2+ HER2 status were evaluated for Her2 and CAIX expression as well as microvessel distribution using triple IHC labelling for HER2, CAIX and CD31. The extension of HER2+ and CAIX+ areas was measured in four directions and CD31 positive capillary distance was measured at 10 regions/case using the Histoquant image analysis software (3DHistech).