Retroperitoneal sarcomas (RPS) are rare tumors composed of several well defined histologic subtypes. The aim of this study was to analyze patterns of recurrence and treatment variations in a large population of patients, treated at reference centers. All consecutive patients with primary RPS treated at 6 European and 2 North American institutions between January 2002 and December 2011 were included. Five, 8, and 10-year overall survival (OS) and crude cumulative incidence (CCI) of local recurrence (LR) and distant metastasis (DM) were calculated. Multivariate analyses for OS, CCI of LR, and DM were performed. In all, 1007 patients were included. Median follow-up was 58 months (first and third quartile range 36-90). The 5, 8, and 10-year OS were 67% [95% confidence interval (CI), 63, 70), 56% (95% CI, 52, 61), and 46% (95% CI, 40, 53). The 5, 8, and 10-year CCI of LR and DM were 25.9 (95% CI, 23.1, 29.1), 31.3 (95% CI, 27.8, 35.1), 35% (95% CI, 30.5, 40.1), and 21% (95% CI, 18.4, 23.8%), 21.6 (95% CI, 19.0, 24.6), and 21.6 (95% CI, 19.0, 24.6), respectively. Tumour size, histologic subtype, malignancy grade, multifocality, and completeness of resection were significant predictors of outcome. Patterns of recurrence varied depending on histologic subtype. Different treatment policies at participating institutions influenced LR of well differentiated liposarcoma without impacting OS, whereas discrepancies in adjuvant systemic therapies did not impact LR, DM, or OS of leiomyosarcoma. Reference centers are critical to outcomes of RPS patients, as the management strategy requires specific expertise. Histologic subtype predicts patterns of recurrence and should inform management decision. A prospective international registry is under preparation, to further define our understanding of this disease.

Purpose: To explore whether the adoption of a systematic attempt to perform wider resections may lead to prognostic improvements in retroperitoneal soft tissue sarcoma (RSTS). Patients and Methods: Two hundred eighty-eight consecutive patients who were surgically treated at a single referral center were analyzed. Because a shift toward a systematic, more aggressive surgical approach (ie, liberal en bloc resection of adjacent organs) was in place from 2002 onward, patients were divided in two groups accordingly. Overall survival, crude cumulative incidence (CCI) of local recurrence, and distant metastases were estimated. Univariable and multivariable analyses were carried out. Results: Patients who underwent operation in the early period had a 5-year local recurrence rate of 48% compared with 28% for patients who were treated in the recent period. The number of distant metastases was greater in the recent group (22% v 13%), and overall survival was similar. In addition to the period of treatment, important independent determinants for local recurrence-free survival were histologic grade, histologic subtype, and radiation therapy. Overall, liposarcomas and grades 1 to 2 tumors had the greatest local benefit at 5 years. Conclusion: In a single institution, the adoption of a policy of more liberal visceral en bloc resections was paralleled by greater local control. This benefit might translate into a prognostic improvement only on a longer follow-up for patients with a more indolent disease, whereas systemic failures seem to be the main problem in high-grade tumors. Radiation therapy could add some additional benefit to local outcome and possibly to survival.

Desmoid-type fibromatosis is a rare and locally aggressive monoclonal, fibroblastic proliferation characterized by a variable and often unpredictable clinical course. Currently, there is no established or evidence-based treatment approach available for this disease. Therefore, in 2015 the European Desmoid Working Group published a position paper giving recommendations on the treatment of this intriguing disease. Here, we present an update of this consensus approach based on professionals’ AND patients’ expertise following a round table meeting bringing together sarcoma experts from the European Organization for Research and Treatment of Cancer/Soft Tissue and Bone Sarcoma Group with patients and patient advocates from Sarcoma PAtients EuroNet. In this paper, we focus on new findings regarding the prognostic value of mutational analysis in desmoid-type fibromatosis patients and new systemic treatment options.

BACKGROUND.: The authors explored the prognostic factors and clinical outcomes of patients who had malignant peripheral nerve sheath tumors (MPNST) with and without neurofibromatosis type 1 (NF‐1).METHODS.: Two hundred five patients with localized MPNST who underwent surgery at the Istituto Nazionale per lo Studio e la Cura dei Tumori (Milan, Italy) over 25 years were reviewed. Forty‐six patients had concomitant NF‐1 syndrome, and 159 patients did not. Local recurrence, distant metastases, and survival rates were studied.RESULTS.: One hundred thirty patients presented with primary disease, and 75 patients had locally recurrent tumors. The disease‐specific mortality rate was 43% at 10 years, with a continuously disease‐free survival rate of no greater than 40%. Presentation with either primary or recurrent disease, tumor size, and tumor site (trunk vs. extremity) were the strongest independent predictors of survival. Margin status and radiation therapy also played a role, mostly related to their effect on local outcome. Pathologic grade influenced distant metastases, but only a trend for survival could be observed. No significant independent differences between patients with and without NF‐1 were observed.CONCLUSIONS.: To the authors' knowledge, this was among the largest single‐institution series to date. The results confirmed that patients with MPNST share similar prognostic factors with patients who have other soft tissue sarcomas and have some of the worst clinical outcomes. The presence of NF‐1 syndrome per se did not affect survival, but patients with NF‐1 were more likely to have larger tumors. Therefore, such patients should be followed carefully to detect disease as early as possible. Cancer 2006. © 2006 American Cancer Society.