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

## TL;DR

This study shows that while imaging can help predict whether soft tissue tumors are benign or malignant, biopsies are still needed in many cases to confirm the diagnosis.

## Contribution

The study provides new evidence on the diagnostic accuracy of multidisciplinary imaging assessments for soft tissue tumors in a prospective clinical setting.

## Key findings

- Multidisciplinary imaging assessments showed high specificity and positive predictive value for benign tumors.
- Despite high accuracy, imaging cannot fully replace biopsies for soft tissue tumor diagnosis.
- Lipomatous tumors can be safely assessed without biopsy in experienced centers.

## Abstract

Soft tissue tumors are rare and heterogeneous in imaging, histology, and prognosis. The prospective study addresses the clinically relevant problems of whether a biopsy of a benign tumor can be safely omitted and whether the exact tumor type can also be predicted based on radiological and clinical/anatomical criteria. The aim of our prospective study is therefore to examine the concordance between histopathological and radiological imaging-based diagnoses of soft tissue tumors in a monocentric, multidisciplinary sarcoma board. We were able to show that in 184 included patients, the comparison of the multidisciplinary sarcoma board’s assessment with the pathological results revealed significant sensitivity and negative predictive value for malignant tumors, as well as significant positive predictive value and significant specificity for benign tumors. The study also shows that, despite the high predictability in an experienced sarcoma center, imaging cannot completely replace a biopsy, and caution should be exercised when deciding against a biopsy.

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.