REtroperitoneal SArcoma Registry: an International Prospective Initiative

Surgery is currently the only potentially curative treatment modality for localized retroperitoneal sarcoma (RPS). Available studies regarding oncologic outcomes are mainly retrospective in nature, and RPS are recognized as a rare disease. Therefore, prospective analysis of high quality data is a top priority. Primary Objectives of this study are: * to prospectively collect standardized clinical data and radiological and pathological material from primary RPS patients treated with surgery at reference centers. * patient outcome will be evaluated in terms of overall survival (OS), disease-free survival (DFS), crude cumulative incidence (CCI) of local recurrence (LR) and distant metastasis (DM). Secondary Objectives: * to estimate the efficacy and safety of surgical treatment, including extended surgical approach to primary RPS; * to prospectively evaluate the impact of multimodality therapy, including radiation therapy and chemotherapy; * to identify clinical, radiological and pathological characteristics that may influence the oncological outcome or may be used as predictors of LR/DM/OS. These may be important biomarkers of disease; * to utilize collected pathological material for research collaborations.

Retroperitoneal sarcomas (RPS) are rare tumors accounting for 10-15% of all soft tissue sarcomas (STS). They arise between retroperitoneal organs and among vital structures (ie major abdominal vessels) in an anatomical compartment that is not readily accessible by physical examination. Four main histotypes account for about 80% of all cases: well-differentiated liposarcoma (WDLPS), dedifferentiated liposarcoma (DDLPS), leiomyosarcoma (LMS) and solitary fibrous tumor (SFT). Compared to sarcomas at other anatomic sites, RPS are burdened by a higher local recurrence (LR) rate (50% at 5 years) and a poorer overall survival (OS) rate (50% at 5-years). The natural history of RPS as a whole group reflects the strong tendency of lipomatous tumors (WDLPS and DDLPS, which account for about 50% of RPS) to recur locally. Indeed, outcome of primary RPS is highly related to the histological subtype. WDLPS are characterized by a relatively lower LR rate, negligible metastatic potential and a favorable overall survival. These tumors however, still may recur locally even years after the primary resection. Intermediate grade DDLPS are characterized by a strong tendency to recur locally and low metastatic potential. High grade DDLPS has a high risk of both local recurrence and distant metastasis. LMS are usually intermediate or high-grade tumors with a strong tendency to develop distant metastasis; with an adequate resection, it is relatively common to obtain a durable local control. Classic SFT usually fare well after surgery, with a low rate of local recurrence and distant metastasis. Historically, surgery emerged as the only potentially curative option in the localized setting. In the last few years there has been lively debate as to how far should a surgeon resect in order to obtain a margin that could be considerate adequate. This issue is particularly challenging in this anatomical compartment where widening the surgical margins means resecting adjacent organs. Since 2002 an 'extended' surgical approach has been proposed for primary RPS patients. The concept was that surgical margins could be improved by encompassing the tumor with en-bloc resection of adjacent organs. The aim was to obtain reduced local recurrence and improved survival. This approach has proven to be effective. In particular, this surgical approach has been supported by an experimental model, retrospective comparisons, pathology studies demonstrating adjacent organ involvement, and reports of high rates of residual tumor at re-excision after conventional (non-extended) primary surgery. Finally, this approach has been shown to be safe after both short and long term follow-up. Radiotherapy is an option for RPS, especially in the preoperative setting, but currently the best evidence for efficacy comes form retrospective, mainly single-center, small size series. The results of such studies are controversial and high quality data are lacking. A randomized prospective study led by EORTC (STRA trial.show_full_description

Inclusion Criteria: * primary RPS operated on in the participating center; * age\>18 years at the time of the first treatment (pediatric patients can not be included) * histological confirmed diagnosis according to the WHO criteria done on biopsy or surgical specimen by dedicated sarcoma pathologist; * radiological examinations performed (contrast enhanced abdominal CT scan and/or MRI) prior to surgical resection; * signed informed consent form; * adequate compliance of the patients to the plan of follow-up Exclusion Criteria: * age\<18 years; * recurrent tumor; * benign retroperitoneal tumors; * serious psychiatric disease that precludes informed consent or limits compliance; * impossibility to ensure adequate follow-up