Prospective Analysis of Multidisciplinary (MDT)-Based Cross-Sectional Imaging to Predict the Histology of Soft Tissue Tumors (BACH-Trial)

Background: The necessity of a pre-therapeutic biopsy for soft tissue tumors is assessed differently depending on imaging. We examined the concordance of histopathological and radiological imaging-based diagnoses of soft tissue tumors in a monocentric, multidisciplinary sarcoma board. Methods: From October 2022 to December 2024, we prospectively included 184 patients presenting with preoperative imaging but without prior histology who are presented at the multidisciplinary sarcoma board of the University Hospital of Erlangen. We evaluated tumor dignity (benign/malignant) and most probable tumor subtype based on cross-sectional imaging assisted by the demographic and anatomic characteristics of individual cases. This assessment was then compared with the final pathological results. Results: We classified 75 tumors as benign and 109 tumors as malignant. Of the 75 patients with a suspected benign tumor, 66 (88%) had a benign diagnosis confirmed by pathological assessment, while two (2.7%) had a malignant tumor and seven (9.3%) an intermediate biology tumor. Of the 109 patients with suspected malignant tumors, 69 (63.3%) had a malignant pathology, while 30 (27.5%) had a benign pathology, and 10 (9.2%) an intermediate tumor. Matching the multidisciplinary sarcoma board’s assessment with the pathological results revealed significant sensitivity and a negative predictive value for malignant tumors, as well as a significant positive predictive value and specificity for benign tumors. Conclusions: The study shows that, despite the high degree of predictability at an experienced sarcoma center, imaging cannot completely replace biopsies and caution should be exercised when deciding against a biopsy. It is emphasized that the decision not to perform a biopsy can only be made in cases where lipomatous tumors appear benign in imaging procedures, and only in an experienced center.