Desmoid tumor (DT; other synonymously used terms: Desmoid-type fibromatosis, aggressive fibromatosis) is a rare and locally aggressive monoclonal, fibroblastic proliferation characterised by a variable and often unpredictable clinical course. Previously surgery was the standard primary treatment modality; however, in recent years a paradigm shift towards a more conservative management has been introduced and an effort to harmonise the strategy amongst clinicians has been made. We present herein an evidence-based, joint global consensus guideline approach to the management of this disease focussing on: molecular genetics, indications for an active treatment, and available systemic therapeutic options. This paper follows a one-day consensus meeting held in Milan, Italy, in June 2018 under the auspices of the European Reference Network for rare solid adult cancers, EURACAN, the European Organisation for Research and Treatment of Cancer (EORTC) Soft Tissue and Bone Sarcoma Group (STBSG) as well as Sarcoma Patients Euro-Net (SPAEN) and The Desmoid tumour Research Foundation (DTRF). The meeting brought

These nomograms accurately predict OS and DFS. They should be used for patient counseling in clinical practice and stratification in clinical trials.

Quality of surgical margins independently predicted local control and survival. The effect on survival was directly mediated by local recurrence to proximal sites invading the abdomen/thorax, and this may indeed be the main way by which quality of surgery directly impacts the final prognosis of ESTS patients.

Frontline aggressive surgical approach to primary RSTS is safe when carried out at high-volume centers. It could be systematically considered in primary RSTS.

This study supports an initial nonsurgical approach to abdominal wall DTs ≤7 cm, followed by surgery based on tumor growth in select cases.