MDM4 amplification in atypical lipomatous tumors/well-differentiated liposarcoma: Private event or alternative oncogenic mechanism?

Adipocytic tumors are the most common mesenchymal tumors in soft tissues. Among them, a diagnostic challenge relies in the distinction between lipoma and atypical lipomatous tumor (ALT)/well differentiated liposarcoma (WDLPS), as both entities are often undistinguishable not only from a radiological point of view, but also at the microscopic level and particularly when dealing with small tumor specimen. Thus, detection of recurrent MDM2 amplifications may be the only criteria to discriminate malignant tumors from lipomas. In this study, we report the case of a patient diagnosed with a well differentiated, adipocytic tumor located in the inferior limb and lacking MDM2 amplification, whose diagnosis was reclassified for ALT/WDLPS after identification of an alternative MDM4 amplification by comparative genomic hybridization profiling, whole exome sequencing and fluorescence in situ hybridization (FISH). Screening of a cohort of 37 large, deep-seated, well-differentiated adipocytic tumors previously classified as lipomas using RT-qPCR and FISH failed to detect other cases of MDM4-amplified ALT/WDLPS. This report shows that MDM4 amplification is an exceptional molecular event alternative to MDM2 amplification in ALT/WDLPS. This alteration should be considered and looked for in suspicious adipocytic tumors to optimize their surgical management.

Preoperative Radiotherapy in Patients With Primary Retroperitoneal Sarcoma: EORTC-62092 Trial (STRASS) Versus Off-trial (STREXIT) Results.

OBJECTIVE: The aim of the present study was to compare the effect of radiotherapy (RT) on abdominal recurrence-free survival (ARFS) in patients with primary retroperitoneal sarcoma treated in the EORTC-STBSG-62092 (STRASS) phase 3 randomized controlled trial (STRASS cohort) and off-trial (STREXIT cohort) and to pool STRASS and STREXIT data to test the hypothesis that RT improves ARFS in patients with liposarcoma. BACKGROUND: The STRASS trial did not show any difference in ARFS between patients treated with preoperative radiotherapy+surgery (RT+S) versus surgery alone (S). METHODS: All consecutive adult patients not enrolled in STRASS and underwent curative-intent surgery for a primary retroperitoneal sarcoma with or without preoperative RT between 2012 and 2017 (STRASS recruiting period) among ten STRASS-recruiting centres formed the STREXIT cohort. The effect of RT in STREXIT was explored with a propensity score (PS)-matching analysis. Primary endpoint was ARFS defined as macroscopically incomplete resection or abdominal recurrence or death of any cause, whichever occurred first. RESULTS: STRASS included 266 patients, STREXIT included 831 patients (727 after excluding patients who received preoperative chemotherapy, 202 after 1:1 PS-matching). The effect of RT on ARFS in STRASS and 1:1 PS-matched STREXIT cohorts, overall and in patients with liposarcoma, was similar. In the pooled cohort analysis, RT administration was associated with better ARFS in patients with liposarcoma [N=321, hazard ratio (HR), 0.61; 95% confidence interval (CI), 0.42-0.89]. In particular, patients with well-differentiated liposarcoma and G1-2 dedifferentiated liposarcoma (G1-2 DDLPS, n=266) treated with RT+S had better ARFS (HR, 0.63; 95% CI, 0.40-0.97) while patients with G3 DDLPS and leiomyosarcoma had not. At the current follow-up, there was no association between RT and overall survival or distant metastases-free survival. CONCLUSIONS: In this study, preoperative RT was associated with better ARFS in patients with primary well-differentiated liposarcoma and G1-2 DDLPS.

Percutaneous Uterine Needle Biopsy with Microscopic and Array-CGH Analyses for Preoperative Sarcoma Diagnosis in Patients with Suspicious Myometrial Tumors on MRI: A Prospective Pilot Study (SARCGYN).

BACKGROUND: Unlike for soft tissue sarcomas, percutaneous biopsy is not validated for uterine myometrial tumors, leading to leiomyosarcoma inadvertent morcellation and overtreatment in childbearing patients. This study aimed to evaluate preoperative percutaneous uterine needle biopsy (PUB) with microscopic examination (M-PUB) and array-comparative genomic hybridization (MCGH-PUB). METHODS: This was a prospective single-center cohort study including all consecutive patients who were candidates for hysterectomy because of suspected uterine leiomyosarcoma on magnetic resonance imaging (MRI) who received PUB. Microscopic and array-CGH analyses with genomic index (GI) counts were performed to guide the therapeutic strategy. Smooth-muscle tumors with suspect features with a GI above 15 were deemed malignant, as were tumors without microscopic malignant features with a complex genomic profile (GI above 30 or malignant profile). Preoperative diagnoses based on M-PUB and MCGH-PUB were compared with the postsurgical pathological specimen or follow-up. RESULTS: From November 2016 to February 2022, 34 patients were included. Based on the surgical specimen (N = 23) or follow-up (N = 11), final diagnoses were 11 sarcomas and 23 non-sarcomas. The median follow-up was 12 months (IQR 6-37). The diagnostic accuracies of M-PUB and MCGH-PUB were 94% and 100%, respectively. The sensitivity, specificity, and negative predictive value of MCGH-PUB were 100%, 100%, and 100%, respectively. A high GI was significantly associated with malignancy (P < 0.001). Genomic analyses allowed malignancy upgrades for four tumors. There were no complications and no dissemination along the biopsy track. CONCLUSION: MCGH-PUB is safe and accurate for preoperatively diagnosing uterine sarcomas and should be used routinely after suspicious MRI to tailor surgery.

Significant Predictors of Postoperative Morbidity After Radical Resection of Retroperitoneal Sarcoma in a Tertiary Center.

BACKGROUND: The safety of multivisceral resection of retroperitoneal sarcoma is an issue. Previous reports have investigated its associations with the pattern of resection and factors recognized mostly per operatively. METHODS: All consecutive RPS resections from May 2015 to April 2022 were studied retrospectively with respect to adverse events. Two univariate and multivariate logistic regression analyses were performed to investigate the associations between severe adverse events and factors recognized pre- and per operatively. Associations of adverse events with overall survival (OS) and local recurrence (LR) were investigated. RESULTS: A total of 265 surgical interventions corresponding to 251 patients were recorded (38 RPS surgeries/year). Severe postoperative adverse events (Clavien-Dindo ≥ 3) occurred in 50 patients (18.9%), 15 (5.6%) patients underwent an iterative laparotomy, and 6 patients (2.3%) died within 90 days. On multivariate analysis including all parameters known preoperatively, male sex, performance status, dedifferentiated liposarcoma histology, and low serum albumin level were found to be significant predictors of major complications, whereas the timing of surgery and preoperative treatment were not. On univariate analysis including all per operative parameters, transfusion requirement, operative time, number of digestive anastomoses, and pancreas and/or major arterial resection were found to entail higher operative risk. On multivariate analysis, only transfusion requirement was significant. There was no impact of postoperative adverse events on OS or LR. CONCLUSIONS: The recognition of preoperative parameters that impact safety could mitigate the extent of the surgery, specifically the resection of adherent organs not overtly invaded. For the best decision, this surgery should be performed in referral centers.

Arterial Reconstruction for En-Bloc Resection of Soft Tissue Sarcoma: A Single Tertiary Center Experience.

BACKGROUND: Tertiary centers recruit a number of locally advanced or recurrent soft tissue sarcomas (STSs) that require large tissue loss including vessels. Arterial reconstruction (AR) in the context of patients with cancer who may receive radiotherapy (RT) and chemotherapy (CT) is challenging. METHODS: This retrospective single centre cohort study includes patients affected by extremities or trunk STS who underwent an AR during sarcoma resection, between October 2015 and February 2021 at Institut Curie. The endpoints of this study were to analyze the morbidity, the patency, and the impact on surgical margins of such associations. RESULTS: Of 976 patients operated, 21 (2.15%) had AR. Seventeen (81%) had American Society of Anesthesiologists (ASA) scores ≥2. Locations were as follows: intra-abdominal n = 9 (43%), lower limb n = 8 (38%), upper limb n = 3 (14%), and cervical n = 1 (5%). N = 11 (52.3%) and n = 5 (23.8%) received RT or were operated on a preirradiated field, respectively. N = 7 (34%) patients received CT. Vein graft was used in n = 12 (57%). Musculo-cutaneous flaps were associated in n = 13 (62%) patients. Margins of resection were R0 n = 19 (90.4%), R1 n = 2, and R2 n = 0. The median follow-up was 16 months [6-44]. No postoperative death occurred. Two patients died of metastasis. At 1, 6, 12, and 24 months the primary patency was 80.9%, 71.4%, 87.5%, and 88.9%, respectively. Seven patients (33%) presented perioperative infection. Reoperation rate at 1, 6, and 12 months were 38%, 14%, and 5%, respectively. Ten patients (48%) presented persistent lymphoedema during follow-up. CONCLUSIONS: AR enlarges the possibilities of STS excision with healthy margins and achieves good patency. Majority of patients were ASA ≥ 2 and received adjuvant treatments. In this particular context, morbidity is high and requires an upfront multidisciplinary management taking into account all these specific issues.

Desmoid tumors: who, when and how to treat?

PURPOSE OF REVIEW: The objective of this article is to summarize new treatment strategies of desmoid tumors. RECENT FINDINGS: Desmoid tumor has an unpredictable evolution that may spontaneously regress or stabilize. A shift toward an initial frontline active surveillance has been acknowledged by experts. Surveillance monitoring should be performed frequently after the diagnosis to avoid missing a significant progression and then spaced in case of stabilization. Treatment is based on significant tumor growth or symptoms. Recent guidelines recommend commencing medical treatment. Kinase inhibitors and cytotoxic agents are the two classes of drugs where studies included progressive desmoid tumors and should be selected to guide medical practice. In a randomized trial, 2 years progression-free survival (PFS) was significantly better in the sorafenib group (81 versus 36% in the placebo group). In another randomized phase 2, 6 months PFS was 83.7% with pazopanib versus 45% with methotrexate and vinblastine. In a retrospective study, including progressive desmoid tumors, methotrexate + vinca alkaloids achieved 75 months median PFS. Cryotherapy is an alternative option in desmoid tumors with compatible locations and tumor sizes. Following medical treatment or cryotherapy failure, superficial sites represent the best indications for surgery in cases of continuous progression. In the event of a contra-indication or failure of medical treatment, in locations where surgery would be mutilating and incomplete, radiotherapy is an effective option. SUMMARY: Active surveillance with planned imaging has become the first-line management in desmoid tumor.

Management of Locally Recurrent Retroperitoneal Sarcoma in the Adult: An Updated Consensus Approach from the Transatlantic Australasian Retroperitoneal Sarcoma Working Group.

BACKGROUND: Surgery is the mainstay of treatment for retroperitoneal sarcoma (RPS), but local recurrence is common. Biologic behavior and recurrence patterns differ significantly among histologic types of RPS, with implications for management. The Transatlantic Australasian RPS Working Group (TARPSWG) published a consensus approach to primary RPS, and to complement this, one for recurrent RPS in 2016. Since then, additional studies have been published, and collaborative discussion is ongoing to address the clinical challenges of local recurrence in RPS. METHODS: An extensive literature search was performed, and the previous consensus statements for recurrent RPS were updated after review by TARPSWG members. The search included the most common RPS histologic types: liposarcoma, leiomyosarcoma, solitary fibrous tumor, undifferentiated pleomorphic sarcoma, and malignant peripheral nerve sheath tumor. RESULTS: Recurrent RPS management was evaluated from diagnosis to follow-up evaluation. For appropriately selected patients, resection is safe. Nomograms currently are available to help predict outcome after resection. These and other new findings have been combined with expert recommendations to provide 36 statements, each of which is attributed a level of evidence and grade of recommendation. In this updated document, more emphasis is placed on histologic type and clarification of the intent for surgical treatment, either curative or palliative. Overall, the fundamental tenet of optimal care for patients with recurrent RPS remains individualized treatment after multidisciplinary discussion by an experienced team with expertise in RPS. CONCLUSIONS: Updated consensus recommendations are provided to help guide decision-making for treatment of locally recurrent RPS and better selection of patients who would potentially benefit from surgery.

Overall survival in patients with re-excision of positive microscopic margins of limb and trunk wall soft tissue sarcoma operated outside of a reference center: a nationwide cohort analysis.

BACKGROUND: This French nationwide NETSARC exhaustive prospective cohort aims to explore the impact of systematic re-excision (RE) as adjuvant care on overall survival (OS), local recurrence free survival (LRFS), and local and distant control (RFS) in patients with soft tissue sarcoma (STS) with positive microscopic margins (R1) after initial resection performed outside of a reference center. METHODS: Eligible patients had experienced STS surgery outside a reference center from 2010 to 2017, and had R1 margins after initial surgery. Characteristics and treatment comparisons used chi-square for categorical variables and Kruskall-Wallis test for continuous data. Survival distributions were compared in patients reexcised (RE) or not (No-RE) using a log-rank test. A Cox proportional hazard model was used for subgroup analysis. RESULTS: A total of 1,284 patients had experienced initial STS surgery outside NETSARC with R1 margins, including 1,029 patients with second operation documented. Among the latter, 698 patients experienced re-excision, and 331 were not re-excised. Characteristics were significantly different regarding patient age, tumor site, tumor size, tumor depth, and histotype in the population of patients re-excised (RE) or not (No-RE). The study identified RE as an independent favorable factor for OS (HR 0.36, 95%CI 0.23-0.56, p<0.0001), for LRFS (HR 0.45, 95%CI 0.36-0.56, p<0.0001), and for RFS (HR 0.35, 95%CI 0.26-0.46, p<0.0001). CONCLUSION: This large nationwide series shows that RE improved overall survival in patients with STS of extremities and trunk wall, with prior R1 resection performed outside of a reference center. RE as part of adjuvant care should be systematically considered.

Management of Primary Retroperitoneal Sarcoma (RPS) in the Adult: An Updated Consensus Approach from the Transatlantic Australasian RPS Working Group.

BACKGROUND: Retroperitoneal soft tissue sarcomas comprise a heterogeneous group of rare tumors of mesenchymal origin that include several well-defined histologic subtypes. In 2015, the Transatlantic Australasian RPS Working Group (TARPSWG) published consensus recommendations for the best management of primary retroperitoneal sarcoma (RPS). Since then, through international collaboration, new evidence and knowledge have been generated, creating the need for an updated consensus document. METHODS: The primary aim of this study was to critically evaluate the current evidence and develop an up-to-date consensus document on the approach to these difficult tumors. The resulting document applies to primary RPS that is non-visceral in origin, with exclusion criteria as previously described. The relevant literature was evaluated and an international group of experts consulted to formulate consensus statements regarding the best management of primary RPS. A level of evidence and grade of recommendation were attributed to each new/updated recommendation. RESULTS: Management of primary RPS was considered from diagnosis to follow-up. This rare and complex malignancy is best managed by an experienced multidisciplinary team in a specialized referral center. The best chance of cure is at the time of primary presentation, and an individualized management plan should be made based on the 29 consensus statements included in this article, which were agreed upon by all of the authors. Whenever possible, patients should be enrolled in prospective trials and studies. CONCLUSIONS: Ongoing international collaboration is critical to expand upon current knowledge and further improve outcomes of patients with RPS. In addition, prospective data collection and participation in multi-institution trials are strongly encouraged.

Morbidity and Outcomes After Distal Pancreatectomy for Primary Retroperitoneal Sarcoma: An Analysis by the Trans-Atlantic Australasian Retroperitoneal Sarcoma Working Group.

BACKGROUND: Multi-visceral resection often is used in the treatment of retroperitoneal sarcoma (RPS). The morbidity after distal pancreatectomy for primary pancreatic cancer is well-documented, but the outcomes after distal pancreatectomy for primary RPS are not. This study aimed to evaluate morbidity and oncologic outcomes after distal pancreatectomy for primary RPS. METHODS: In this study, 26 sarcoma centers that are members of the Trans-Atlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG) retrospectively identified consecutive patients who underwent distal pancreatectomy for primary RPS from 2008 to 2017. The outcomes measured were 90-day severe complications (Clavien-Dindo ≥ 3), postoperative pancreatic fistula (POPF) rate, and oncologic outcomes. RESULTS: Between 2008 and 2017, 280 patients underwent distal pancreatectomy for primary RPS. The median tumor size was 25 cm, and the median number of organs resected, including the pancreas, was three. In 96% of the operations, R0/R1 resection was achieved. The 90-day severe complication rate was 40 %. The grades B and C POPF complication rates were respectively 19% and 5% and not associated with worse overall survival. Administration of preoperative radiation and factors to mitigate POPF did not have an impact on the risk for the development of a POPF. The RPS invaded the pancreas in 38% of the patients, and local recurrence was doubled for the patients who had a microscopic, positive pancreas margin (hazard ratio, 2.0; p = 0.042). CONCLUSION: Distal pancreatectomy for primary RPS has acceptable morbidity and oncologic outcomes and is a reasonable approach to facilitate complete tumor resection.

Simultaneous combined anterior and posterior approach for en bloc resection of sciatic notch sarcomas.

BACKGROUND: Monobloc resection of soft tissue sarcomas (STSs) has a major impact on overall survival and local recurrence. Anatomical boundaries, such as the sciatic notch, increase the risk of fragmentation of the lesion. To date there are few papers describing the optimal surgical technique to remove such STSs. The objective of this study is to describe a simultaneous anterior and posterior approach for resection of sciatic notch dumbbell tumours. CASE PRESENTATION: We present the surgical management of two patients diagnosed with well-differentiated liposarcomas of the sciatic notch with a retroperitoneal and gluteal extension in the two cases. Pre-operative diagnosis was made with a percutaneous biopsy including molecular analysis which demonstrated MDM2 amplification. We describe a simultaneous anterior and posterior approach, including the ligation of the posterior trunk of the internal iliac artery, to reduce intra-operative blood loss and devascularise the tumour. The anterior approach allows the evaluation of the tumour's retroperitoneal extension, release from its pelvic attachments and control of the surrounding neurovascular structures. During the posterior approach, bleeding is reduced by the devascularisation of the gluteal musculature achieved with internal iliac artery ligation. Clear margins were achieved in both cases. No vascular, skeletal or soft tissue reconstructions were required. CONCLUSIONS: Simultaneous combined anterior and posterior approaches to remove a malignant sciatic notch tumour optimises the chance of complete en bloc resection. This surgical strategy allows oncologic en bloc resection with minimal blood loss.

Major vascular resections in retroperitoneal sarcoma.

Retroperitoneal sarcomas (RPS) frequently involve major vessels, which either originate from them or secondarily encase or invade them. In this field, major vascular resections result in increased morbidity. However, survival does not seem to be affected by the need for vascular resection or by this higher morbidity. This paper aims to provide descriptions of the surgical strategy and outcomes for retroperitoneal sarcomas involving major vessels.

Primary Extremity Soft Tissue Sarcomas: Does Local Control Impact Survival?

BACKGROUND: The objective of this study was to evaluate the adequate margin in the local treatment of extremity soft tissue sarcomas (ESTS) and understand the relationship between local control and overall survival (OS). METHODS: All consecutive patients treated for a primary ESTS at a single center from 1993 to 2012 were reviewed. RESULTS: In all, 531 patients were included. Twelve (2 %) underwent a first-line amputation. The resections were R0/R1/not available in 434 (82 %), 92 (17 %), and 5 patients (1 %). The median tumor size was 8 cm, and the tumor grades were 1 (n = 132), 2 (n = 201), and 3 (n = 195). The median size of the minimal margin was 2 mm on fixed specimen. Preop or postop chemotherapy was administered to 222 patients, and 414 received radiotherapy. With a median follow-up period of 7 years, the 5-year actuarial local recurrence (LR) rate and OS were 8 % (95 % CI, 6-11 %) and 80 % (95 % CI, 76-83 %). Predictors of worse OS were grade 3, leiomyosarcoma, male gender, and age >60 years, whereas tumor size, margin status, and LR were not. Among patients requiring re-excision (n = 252), the presence of residual cells correlated with OS but not LR. After preoperative treatment, a percentage of residual cells ≥10 % correlated with OS but not LR. In the multivariate analysis, specific subtypes (epithelioid sarcoma and myxofibrosarcoma) and margin size <1 mm correlated with LR, whereas grade and the tissue constituting the surgical margins did not. CONCLUSIONS: Specific subtypes and surgical margin size <1 mm were correlated with a higher LR. Neither the margin status nor LR affect OS.

Diagnostic accuracy and safety of percutaneous core needle biopsy of retroperitoneal tumours.

BACKGROUND: Histologic subtype of cancer guides treatment sequencing and the extent of surgery for retroperitoneal tumours (RPTs) but concerns persist regarding percutaneous core needle biopsy (CNB). OBJECTIVE: Endpoints were the incidence of early complications, needle tract seeding (NTS) after CNB, diagnostic accuracy. METHODS: Between 2015 and 2022, data from patients with RPT who underwent a CNB and who operated on at Institut Curie were collected. We retrospectively reviewed the medical records and microscopic analysis of both CNB and surgical specimens to evaluate the diagnostic accuracy of CNB (quantified using positive and negative predictive values, PPV/NPV). RESULTS: 313 patients underwent CNB. In 10/326 (3 %) procedures, minor complications were observed. One of 212 (0.47 %) resected RPSs exhibited a local recurrence compatible with NTS. Microscopic analysis of CNB specimens allowed the classification of tumours between groups of cancers and benign/intermediate mesenchymal tumours in 307/313 (98 %) patients. Among the 204 patients with retroperitoneal sarcoma, the overall concordance between CNB and final pathology following resection was 178/204 (87.2 %). The respective PPVs of solitary fibrous tumour, dedifferentiated liposarcoma, leiomyosarcoma and well-differentiated liposarcoma were 100 %, 98 %, 97 % and 68 %, respectively. The diagnosis of a high-grade (G 2-3) sarcoma resulted in a high specificity (97 %) and PPV (98 %) but low sensitivity (76 %). CONCLUSIONS: CNB allowed the classification of RPT in the vast majority of patients with a low morbidity rate. Concordance with final diagnosis was high for sarcomas with the exception of well-differentiated liposarcoma. As a result, CNB results should be integrated with imaging/radiomics by multidisciplinary tumour boards.

Cellular origin and clonal evolution of human dedifferentiated liposarcoma.

Dedifferentiated liposarcoma (DDLPS) is the most frequent high-grade soft tissue sarcoma subtype. It is characterized by a component of undifferentiated tumor cells coexisting with a component of well-differentiated adipocytic tumor cells. Both dedifferentiated (DD) and well-differentiated (WD) components exhibit MDM2 amplification, however their cellular origin remains elusive. Using single-cell RNA sequencing, DNA sequencing, in situ multiplex immunofluorescence and functional assays in paired WD and DD components from primary DDLPS tumors, we characterize the cellular heterogeneity of DDLPS tumor and micro-environment. We identify a population of tumor adipocyte stem cells (ASC) showing striking similarities with adipocyte stromal progenitors found in white adipose tissue. We show that tumor ASC harbor the ancestral genomic alterations of WD and DD components, suggesting that both derive from these progenitors following clonal evolution. Last, we show that DD tumor cells keep important biological properties of ASC including pluripotency and that their adipogenic properties are inhibited by a TGF-ß-high immunosuppressive tumor micro-environment.

Improved Metastatic-Free Survival after Systematic Re-Excision Following Complete Macroscopic Unplanned Excision of Limb or Trunk Soft Tissue Sarcoma.

BACKGROUND: Whether re-excision (RE) of a soft tissue sarcoma (STS) of limb or trunk should be systematized as adjuvant care and if it would improve metastatic free survival (MFS) are still debated. The impact of resection margins after unplanned macroscopically complete excision (UE) performed out of a NETSARC reference center or after second resection was further investigated. METHODS: This large nationwide series used data from patients having experienced UE outside of a reference center from 2010 to 2019, collected in a French nationwide exhaustive prospective cohort NETSARC. Patient characteristics and survival distributions in patients reexcised (RE) or not (No-RE) are reported. Multivariate Cox proportional hazard model was conducted to adjust for classical prognosis factors. Subgroup analysis were performed to identify which patients may benefit from RE. RESULTS: Out of 2371 patients with UE for STS performed outside NETSARC reference centers, 1692 patients were not reviewed by multidisciplinary board before treatment decision and had a second operation documented. Among them, 913 patients experienced re-excision, and 779 were not re-excised. Characteristics were significantly different regarding patient age, tumor site, size, depth, grade and histotype in patients re-excised (RE) or not (No-RE). In univariate analysis, final R0 margins are associated with a better MFS, patients with R1 margins documented at first surgery had a better MFS as compared to patients with first R0 resection. The study identified RE as an independent favorable factor for MFS (HR 0.7, 95% CI 0.53-0.93; p = 0.013). All subgroups except older patients (>70 years) and patients with large tumors (>10 cm) had superior MFS with RE. CONCLUSIONS: RE might be considered in patients with STS of limb or trunk, with UE with macroscopic complete resection performed out of a reference center, and also in originally defined R0 margin resections, to improve LRFS and MFS. Systematic RE should not be advocated for patients older than 70 years, or with tumors greater than 10 cm.

Activation of lysosomal iron triggers ferroptosis in cancer.

Iron catalyses the oxidation of lipids in biological membranes and promotes a form of cell death referred to as ferroptosis1-3. Identifying where this chemistry takes place in the cell can inform the design of drugs capable of inducing or inhibiting ferroptosis in various disease-relevant settings. Whereas genetic approaches have revealed underlying mechanisms of lipid peroxide detoxification1,4,5, small molecules can provide unparalleled spatiotemporal control of the chemistry at work6. Here, we show that the ferroptosis inhibitor liproxstatin-1 (Lip-1) exerts a protective activity by inactivating iron in lysosomes. Based on this, we designed the bifunctional compound fentomycin that targets phospholipids at the plasma membrane and activates iron in lysosomes upon endocytosis, promoting oxidative degradation of phospholipids and ferroptosis. Fentomycin effectively kills primary sarcoma and pancreatic ductal adenocarcinoma cells. It acts as a lipolysis-targeting chimera (LIPTAC), preferentially targeting iron-rich CD44high cell-subpopulations7,8 associated with the metastatic disease and drug resistance9,10. Furthermore, we demonstrate that fentomycin also depletes CD44high cells in vivo and reduces intranodal tumour growth in an immunocompetent murine model of breast cancer metastasis. These data demonstrate that lysosomal iron triggers ferroptosis and that lysosomal iron redox chemistry can be exploited for therapeutic benefits.