Studies

Rationale: Patients with an atypical lipomatous tumor (ALT) have an excellent prognosis, approaching 100% survival after 10 years of follow-up. Currently, we might be ‘overtreating’ these patients with surgery and radiotherapy, thereby inducing morbidity and even mortality. Despite this excellent prognosis, active surveillance is barely applied in these patients. Furthermore, survival might not be the only appropriate outcome to measure, and other outcomes, such as health-related quality of life (HRQoL), might have become more relevant. Second, it can be very difficult to distinguish between ALTs and lipomas based on imaging. Therefore, these patients currently need a painful and invasive biopsy for pathological examination to make the distinction. Finally, due to the rarity and heterogeneity of liposarcomas, it is a challenge to collect a large homogeneous set of tissue samples for translational research. Objective: The aim is to develop a minimally invasive approach of both diagnosing and treating ALTs, saving these patients a biopsy, surgery-related complications and morbidities amongst others. As a first step towards a minimally invasive diagnosis, a radiomics model was developed on a retrospective cohort to distinguish lipomas from ALTs based on MRI scans. In the current study, one of the objectives is to prospectively validate this radiomics model. Second, to prevent the ‘overtreatment’ of ALT patients, the aim is to explore the feasibility and safety of active surveillance (AS) as a treatment option for ALTs, including evaluating the HRQoL. Lastly, the objective is to build a biobank of the biopsies and, if applicable, resection specimens obtained during the study for future translational research.

Aged ≥18 years Primary or recurrent lipomatous tumor suspected for lipoma or atypical lipomatous tumor Adequate understanding of the Dutch or English language (to fill out the HRQoL questionnaires)

Tumor localization in the mediastinum, retroperitoneum or testis/scrotum Diagnosis through excisional biopsy Any type of treatment for the current tumor (i.e. in case of recurrence, treatment of the prior tumor(s) is allowed) Signs/suspicion of dedifferentiation in the biopsy specimen at time of diagnosis Unable to undergo regular MRI-scans (for example because of a pacemaker, claustrophobia) Systemic treatment for any other concurrent malignancy Currently receiving radiotherapy at affected site for other concurrent disease Incapable to understand the study, to sign informed consent or to fill out the HRQoL-questionnaires

Name: Anne-Rose Schut Email: minimalist@erasmusmc.nl Phone: 010 704 12 23