(P 138) CONTROVERSIES IN THE MANAGEMENT OF PATIENTS WITH SOFT TISSUE SARCOMA: RESULTS AND RECOMMENDATIONS FROM THE FIRST CONFERENCE ON STATE OF SCIENCE IN SARCOMA (CSSS)

Objective: International guidelines on soft tissue sarcoma (STS) cover primarily aspects, for which good quality evidence exists. However, they do not cover controversial topics discussed among sarcoma experts in the absence of prospective data or in case of conflicting results from small retrospective or low-quality studies. Consensus expert recommendations are therefore needed to complement these guidelines.

Methods: We organized a consensus meeting of 62 European sarcoma experts from 12 countries, covering different specialities involved in research and management of patients with STS. We used a modified Delphi process to identify and evaluate 220 controversial questions regarding STS diagnostics, peri-operative, local, and palliative treatment, follow-up, trial design, and politics. A recommendation agreed upon by >=75% panelists was defined as a “consensus”, while an agreement by >=95% of the panelists was characterized as “strong consensus”. The process was designed to allow the identification of areas without consensus, where additional data collection or future research was deemed necessary.

Results: A consensus could be reached in 30 topics, such as recommending a core-needle rather than incisional biopsy for histological diagnosis, and preoperative rather than postoperative chemotherapy in patients with extremity or trunk wall STS. There was also consensus in the preferred treatment of patients with metachronous oligometastatic disease involving both local and systemic treatments, and in recommending against reimbursement of STS surgery outside reference centers. The panelists also consented that the radiographic features of STS should be considered when estimating STS grade, especially if tumor grading is not conclusive on biopsy, and that quality of life, socioeconomic (including insurance issues), and psychological aspects should be systematically and longitudinally assessed in daily clinical practice.
There was strong consensus in additional 16 topics, such as basing surgical strategies on both tumor characteristics and surgical morbidity/function preservation, recommending randomized discontinuation trials in palliative patients with slowly growing STS achieving stable-disease, including all patients with newly recognized molecular entities in international registries and requiring a a combined response score from pathology and radiology in future trials.
On the other hand, no consensus was achieved on how high-risk STS or the adolescent and young adult (AYA) population should be defined, the goals of surgical treatment in patients with progressive disease under preoperative treatment, or the optimal time interval between preoperative radiotherapy and subsequent surgery. There was also no consensus on the treatment sequence for high-risk extremity or trunk wall STS, on treatment recommendations following an unplanned R1/R2 excision (whoops resection) with or without macroscopic tumor left, on when next-generation-sequencing should be performed in the palliative setting or on the optimal endpoints for future trials in advanced/metastatic STS.

Conclusion: Several consensus recommendations could be identified, however they comprised only 21% of the available topics. For a variety of sarcoma management aspects, future research questions could be formulated, whereas for some topics, it appears unlikely that there will ever be sufficient data or a consensus.