CORRELATION OF RADIOLOGICAL AND PATHOLOGICAL TUMOR SIZES IN EARLYSTAGE BREAST CANCER BASED ON MOLECULAR SUBTYPES AND PRESENCE OF IN SITU CARCINOMA: A RETROSPECTIVE MULTICENTER STUDY.

Purpose: To compare radiological tumor sizes obtained by mammography (MMG), ultrasonography (US) and magnetic resonance imaging (MRI) with pathological sizes and to determine whether there are any changes based on molecular subtypes and the presence of accompanying ductal carcinoma in situ (DCIS). Methods: A total of 559 cases diagnosed with breast cancer in 11 different centers between 2010 and 2022 were included in the study. Tumor sizes were measured on the images downloaded from PACS and compared later with the pathologic sizes reported in the postoperative pathology reports. Comparison was performed based on patient age, imaging findings, breast density, histologic type (invasive/ in situ/ mixed), molecular subtypes and presence of accompanying benign or high-risk lesions. “Mann Whitney U’’ and “Kruskal Wallis H’’ tests were used for comparisons between groups, “Chi-Square or Fisher’s Exact Test” was used to compare categorical variables, and “Spearman Correlation Analysis” was used to examine the relationship between continuous variables. Results: The highest agreement in invasive tumors was obtained with MRI (MRI: 0.831, US: 0.769, MMG: 0.650). In the presence of DCIS, the agreement was strong with MRI (r: 0.770) and moderate with MMG and US (r: 0.517 and r: 0.593, respectively). In mixed tumors, agreement was strong with MRI (r:0.817), moderate with US (r:0.656), and low with mammography (r:0.499). Based on molecular subtypes, highest correlation was obtained with US and MRI in HER-2 (+) tumors (r:0.754, and r:0.715, respectively), and with MRI in other subtypes (Luminal A-B- triple (-)) with MRI (r:0.856-0.815-0.858; respectively). There was no statistically significant difference in terms of other criteria. Conclusion: This multicenter study shows that MRI is the most reliable method in preoperative determination of tumor size for both invasive and in-situ tumors and all molecular subtypes. [ABSTRACT FROM AUTHOR]