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

PURPOSE To determine the prognostic significance of histologic type in radiation-associated soft tissue sarcomas (RASs) and determine whether RASs are associated with an inferior prognosis compared with sporadic soft tissue sarcomas (STSs). PATIENTS AND METHODS One hundred thirty primary RASs were identified from 7,649 STS patients from 1982 to 2007. Multivariate analysis of clinicopathologic factors for disease-specific survival (DSS) was performed for RASs, and a multivariate analysis of radiation exposure was also performed for RASs and sporadic sarcomas. A matched-cohort analysis was performed for radiation-associated and sporadic malignant fibrous histiocytoma (MFH). Results Most RASs were high grade (83%), deep (87%), and truncal (61.5%). The median interval between radiation therapy and RAS development was 10 years (range, 1.3 to 74 years), which varied significantly by histologic type (P = .003). The 5-year DSS was 58%, and independent predictors were size > 5 cm, margin positivity, and histologic type. Multivariate analysis of histologic types of primary, high-grade radiation-associated and sporadic STSs showed that RAS was associated with a worse DSS (hazard ratio, 1.7; range, 1.1 to 2.4; P = .007). For pleomorphic MFH-the most common RAS type-the 5-year DSS was 44% versus 66% in a matched cohort of sporadic MFH patients (P = .07). DSS was significantly worse in primary RAS malignant peripheral nerve sheath tumors (MPNSTs) compared with unmatched sporadic MPNSTs (P = .001). CONCLUSION Histologic type, margin status, and tumor size are the most important independent predictors of DSS in patients with RASs. DSS in patients with primary RAS is significantly worse compared with sporadic STS independent of sarcoma histologic type.

Background Leiomyosarcoma is a soft tissue sarcoma whose outcome has historically been confounded by the inclusion of gastrointestinal stromal tumors. Thus, we sought to determine the factors that predict survival and recurrence in patients with primary leiomyosarcoma alone. Methods During 1982–2006, 353 patients with primary resectable leiomyosarcoma were identified from a prospective database. Multivariate analysis was used to assess clinicopathologic factors for association with disease-specific survival (DSS). Competing risk survival analysis was used to determine factors predictive for local and distant recurrence. Results Of 353 patients, 170 (48%) presented with extremity, 144 (41%) with abdominal/retroperitoneal, and 39 (11%) with truncal tumors. Median age was 57 years (range, 18–88), and median follow-up was 50 months (1–270). Most tumors were high grade (75%), deep (73%), and completely resected (97%); median size was 6.0 cm (range, 0.3–45 cm). Abdominal/retroperitoneal location was associated with worse long-term DSS compared to extremity or trunk (P=0.005). However, by multivariate analysis, only high grade and size were significant independent predictors of DSS. Overall, 139 patients (39%) had recurrence: 51% of abdominal/retroperitoneal, 33% of extremity, and 26% of truncal patients. Significant independent predictors for local recurrence were size and margin, whereas predictors for distant recurrence were size and grade. Site was not an independent predictor of recurrence; however, late recurrence (> 5 years) occurred in 9% of abdominal/retroperitoneal and 4% of extremity lesions. Conclusions Grade and size are significant independent predictors of DSS and distant recurrence. Long-term follow-up in leiomyosarcoma is important, as late recurrence continues in 6–9% patients.

Aneuploidy is a characteristic feature of established cancers and can promote tumor development. Aneuploidy may arise directly, through unequal distribution of chromosomes into daughter cells, or indirectly, through a tetraploid intermediate. The polo family kinase Plk4/Sak is required for late mitotic progression and is haploinsufficient for tumor suppression in mice. Here we show that loss of heterozygosity (LOH) occurs at the Plk4 locus in 50% of human hepatocellular carcinomas (HCC) and is present even in preneoplastic cirrhotic liver nodules. LOH at Plk4 is associated with reduced Plk4 expression in HCC tumors but not with mutations in the remaining allele. Plk4 +/− murine embryonic fibroblasts (MEFs) at early passage show a high incidence of multinucleation, supernumerary centrosomes, and a near-tetraploid karyotype. Underlying these phenotypes is a high rate of primary cytokinesis failure, associated with aberrant actomyosin ring formation, reduced RhoA activation, and failure to localize the RhoA guanine nucleotide exchange factor Ect2 to the spindle midbody. We further show that Plk4 normally localizes to the midbody and binds to and phosphorylates Ect2 in vitro. With serial passaging Plk4 +/− MEFs rapidly immortalize, acquiring an increasing burden of nonclonal and clonal gross chromosomal irregularities, and form tumors in vivo. Our results indicate that haploid levels of Plk4 disrupt RhoGTPase function during cytokinesis, resulting in aneuploidy and tumorigenesis, thus implicating early LOH at Plk4 as one of the drivers of human hepatocellular carcinogenesis. These findings represent an advance in our understanding of genetic predisposition to HCC, which continues to increase in incidence globally and particularly in North America.aneuploidy | hepatocellular carcinoma | Polo-like kinase | RhoA | Ect2

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Double-strand DNA breaks (DSB) induce chromosomal translocations and gene amplification in cell culture, but mechanisms by which DSB cause genomic instability in vivo are poorly understood. We show that RAG-1/2-induced DSB cause IgH/c-Myc translocations in leukemic pro-B cells from p53/Prkdc-deficient mice. Strikingly, these translocations were complex, clonally heterogeneous and amplified. We observed reiterated IgH/c-Myc fusions on dicentric chromosomes, suggesting that amplification occurred by repeated cycles of bridge, breakage and fusion. Leukemogenesis was not mitigated in RAG-2/p53/Prkdc-deficient mice, but leukemic pro-B cells lacked IgH/c-Myc translocations. Thus, global genomic instability conferred by p53/Prkdc disruption efficiently transforms pro-B cells lacking RAG-1/2-induced DSB. Unexpectedly, RAG-2/p53/Prkdc-deficient mice also developed leptomeningeal leukemia, providing a novel spontaneous model for this frequent complication of human lymphoblastic malignancies.

The DSS is excellent for type I GC patients treated with either ES or SR. SR should be considered with more advanced carcinoid disease given its association with an increased risk of adenocarcinoma. ES is appropriate to assess both the status of carcinoid disease and dysplasia or adenocarcinoma that can develop in association with type I GC.

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