Extracellular Vesicle - MDM2-DNA as a Potential Liquid Biopsy Biomarker for Disease Identification in Retroperitoneal Liposarcoma.

OBJECTIVE: We aimed to assess the levels of MDM2-DNA within extracellular vesicles (EVs) isolated from the serum of retroperitoneal liposarcoma (RLS) patients versus healthy donors, as well as within the same patients at the time of surgery versus post-operative surveillance visits. To determine whether EV-MDM2 may serve as a possible first-ever biomarker of liposarcoma recurrence. BACKGROUND: A hallmark of well-differentiated and de-differentiated (WD/DD) retroperitoneal liposarcoma is elevated MDM2 due to genome amplification, with recurrence rates of >50% even after complete resection. Imaging technologies frequently cannot resolve recurrent WD/DD-RLS versus postoperative scarring. Early detection of recurrent lesions, for which biomarkers are lacking, would guide surveillance and treatment decisions. METHODS: WD/DD-RLS serum samples were collected both at the time of surgery and during follow-up visits from 42 patients, along with sera from healthy donors (n=14). EVs were isolated, DNA purified and MDM2-DNA levels determined through q-PCR analysis. Non-parametric tests were employed to compare EV-MDM2 DNA levels from patients versus control group, as well as the time of surgery versus post-surgery conditions. RESULTS: EV-MDM2 levels were significantly higher in WD/DD-RLS than controls (P= 0.00085). Moreover, EV-MDM2 levels were remarkably decreased in WD/DD-RLS patients after resection (P=0.00036), reaching values comparable to control group (P=0.124). During post-operative surveillance, significant increases of EV-MDM2 was observed in some patients, correlating with CT scan evidence of recurrent or persistent post-resection disease. CONCLUSIONS: Serum EV-MDM2 may serve as a potential biomarker of early recurrent or post-operatively persistent WD/DD-RLS, a disease currently lacking such determinants.

Natural history of undifferentiated pleomorphic sarcoma: Experience from the US Sarcoma Collaborative.

BACKGROUND: Undifferentiated pleomorphic sarcoma (UPS) is a relatively rare but aggressive neoplasm. We sought to utilize a multi-institutional US cohort of sarcoma patients to examine predictors of survival and recurrence patterns after resection of UPS. METHODS: From 2000 to 2016, patients with primary UPS undergoing curative-intent surgical resection at seven academic institutions were retrospectively reviewed. Epidemiologic and clinicopathologic factors were reviewed by site of origin. Overall survival (OS), recurrence-free survival (RFS), time-to-locoregional (TTLR), time-to-distant recurrence (TTDR), and patterns of recurrence were analyzed. RESULTS: Of the 534 UPS patients identified, 53% were female, with a median age of 60 and median tumor size of 8.5 cm. The median OS, RFS, TTLR, and TTDR for the entire cohort were 109, 49, 86, and 46 months, respectively. There were no differences in these survival outcomes between extremity and truncal UPS. Compared with truncal, extremity UPS were more commonly amenable to R0 resection (87% vs. 75%, p = 0.017) and less commonly associated with lymph node metastasis (1% vs. 6%, p = 0.031). R0 resection and radiation treatment, but not site of origin (extremity vs. trunk) were independent predictors of OS and RFS. TTLR recurrence was shorter for UPS resected with a positive margin and for tumors not treated with radiation. CONCLUSION: For patients with resected extremity and truncal UPS, tumor size >5 cm and positive resection margin are associated with worse survival OS and RFS, irrespectively the site of origin. R0 surgical resection and radiation treatment may help improve these survival outcomes.

Radiation therapy for retroperitoneal sarcoma: practice patterns in North America.

BACKGROUND: The addition of radiation therapy (RT) to surgery in retroperitoneal sarcoma (RPS) remains controversial. We examined practice patterns in the use of RT for patients with RPS over time in a large, national cohort. METHODS: Patients in the National Cancer Database (2004-2017) who underwent resection of RPS were included. Trends over time for proportions were calculated using contingency tables with Cochran-Armitage Trend test. RESULTS: Of 7,485 patients who underwent resection, 1,821 (24.3%) received RT (adjuvant: 59.9%, neoadjuvant: 40.1%). The use of RT decreased annually by < 1% (p = 0.0178). There was an average annual increase of neoadjuvant RT by 13% compared to an average annual decrease of adjuvant RT by 6% (p < 0.0001). Treatment at high-volume centers (OR 14.795, p < 0.0001) and tumor > 10 cm (OR 2.009, p = 0.001) were associated with neoadjuvant RT. In contrast liposarcomas (OR 0.574, p = 0.001) were associated with adjuvant RT. There was no statistically significant difference in overall survival between patients treated with surgery alone versus surgery and RT (p = 0.07). CONCLUSION: In the United States, the use of RT for RPS has decreased over time, with a shift towards neoadjuvant RT. However, a large percentage of patients are still receiving adjuvant RT and this mostly occurs at low-volume hospitals.

Comparing Multivisceral Resection with Tumor-only Resection of Liposarcoma Using the Win Ratio.

BACKGROUND: Multivisceral resection of retroperitoneal liposarcoma (LPS) is associated with increased morbidity and may not confer a survival benefit compared with tumor-only (TO) resection. We compared both approaches using a novel statistical method called the "win ratio" (WR). METHODS: Patients who underwent resection of LPS from 2004 to 2015 were identified from the National Cancer Database. Multivisceral resection was defined as removal of the primary site in addition to other organs. The WR was calculated based on a hierarchy of postoperative outcomes: 30-day and 90-day mortality, long-term survival, and severe complication. RESULTS: Among 958 patients (multivisceral 634, TO 324) who underwent resection, the median age was 63 years (interquartile range [IQR] 54-71) with a median follow-up of 51 months (IQR 30-86). There was no difference in the WR among patients who underwent TO versus multivisceral resection in the matched cohort (WR 0.82, 95% confidence interval [CI] 0.61-1.10). In patients aged 72-90 years, those who underwent multivisceral resection had 36% lower odds of winning compared with patients undergoing TO resection (WR 0.64, 95% CI 0.40-0.98). A subgroup analysis of patients classified as not having adjacent tumor involvement at the time of surgery revealed that those patients who underwent multivisceral resection had 33% lower odds of winning compared to TO resection (WR 0.67, 95% CI 0.45-0.99). CONCLUSIONS: Based on win-ratio assessments of a hierarchical composite endpoint, multivisceral resection in patients without adjacent tumor involvement may not confer improved outcomes. This method supports the rationale for less invasive resection of LPS in select patients, especially older patients.

Disparities in Survival and NCCN Guideline-Concordant Care in Patients With Extremity Soft Tissue Sarcoma.

BACKGROUND: Based on the NCCN Guidelines for Soft Tissue Sarcoma (STS), treatment of extremity STS (ESTS) includes radiation therapy (RT) and surgical resection for tumors that are high-grade and >5 cm. ​​The aim of this study was to describe the association between neighborhood socioeconomic status (nSES), concordance with NCCN Guidelines recommendations, and outcomes in patients with ESTS. METHODS: Patients with ESTS diagnosed from 2006 through 2018 were identified in SEER registries. The analytic cohort was restricted to patients with high-grade tumors >5 cm without nodal or distant metastases who received limb-sparing surgery. Patient demographics and tumor characteristics associated with receipt of RT were analyzed using adjusted regression analyses. Kaplan-Meier curves and adjusted accelerated failure time models were used to examine disparities in cancer-specific survival. RESULTS: Of 2,249 patients, 29.0% (n=648) received neoadjuvant RT, 49.7% (n=1,111) received adjuvant or intraoperative RT, and 21.3% (n=476) did not receive RT. In adjusted analyses, lower nSES was associated with lower likelihood of receiving RT (odds ratio, 0.70 [95% CI, 0.57-0.87]; P<.001). Low nSES was associated with worse cancer-specific survival (hazard ratio, 1.19 [95% CI, 1.01-1.40]; P=.04). Race and ethnicity were not significant predictors of receipt of RT or cancer-specific survival in the fully adjusted models. CONCLUSIONS: Patients from lower nSES areas were less likely to receive NCCN Guideline-recommended RT for their ESTS and had worse cancer-specific survival. Efforts to better define and resolve disparities in the treatment and survival of patients with ESTS are warranted.

Preoperative radiation therapy increases adherence in patients with high-risk extremity soft tissue sarcoma.

BACKGROUND: Surgery and radiation therapy remain the standard of care for patients with high-grade extremity soft tissue sarcoma that are >5 cm. Radiation therapy is time and labor-intensive for patients, and social determinants of health may affect adherence. The aim of this study was to define demographic, clinical, and treatment factors associated with the completion of radiation therapy and determine if preoperative radiation therapy improved adherence compared to postoperative radiation therapy. METHODS: The cohort included patients in the National Cancer Database with high-grade extremity soft tissue sarcoma >5 cm without nodal or distant metastases who received limb-sparing surgery and radiation therapy with microscopically negative R0 margins. Multivariable logistic regression analyses identified factors associated with radiation therapy sequencing and adherence (defined as completion of 50 Gy preoperative radiation therapy or at least 60 Gy postoperative radiation therapy). A multivariable Cox Proportional Hazards model assessed overall survival. RESULTS: Among 2,145 patients, 47.1% received preoperative radiation therapy (n = 1,010), and 52.9% (n = 1135) received postoperative radiation therapy. A greater proportion of patients treated with preoperative (77.2%) versus postoperative radiation therapy (64.9%, P < .0001) received the recommended dose. More patients with private insurance (49.8% vs 35.3% Medicaid vs 44.9% Medicare, P = .011) and patients treated at an academic medical center (52.6% vs 47.4%, P < .001) received preoperative radiation therapy. Patients who received preoperative radiation therapy had lower odds of receiving insufficient doses of radiation therapy (odds ratio 0.34 [95% CI 0.27-0.47]). Neither radiation therapy adherence nor sequencing were independent predictors of overall survival. CONCLUSIONS: Patients who received preoperative radiation therapy were more likely to complete therapy and receive an optimal dose than patients treated with postoperative radiation therapy. Preoperative radiation therapy improves adherence and should be widely considered in patients with high-grade extremity soft tissue sarcoma, particularly in patients at risk for not completing therapy.

Adjuvant Palbociclib May be Associated with Delayed Recurrence in Completely Resected Retroperitoneal Liposarcoma: Results of a Single-Institution Retrospective Cohort Study.

BACKGROUND: Retroperitoneal liposarcomas are locally aggressive and frequently recur following complete surgical resection. Palbociclib, a cyclin-dependent kinase (CDK) 4/CDK6 inhibitor, is effective in the treatment of metastatic or unresectable liposarcoma. OBJECTIVE: The purpose of this study was to describe our initial experience using adjuvant palbociclib to delay recurrence. METHODS: Patients with resected RPS were identified from a prospectively maintained institutional database. In 2017, we began offering adjuvant palbociclib to patients following complete gross resection. Treatment interval, defined as the time between surgical resection and re-resection or change in systemic therapy, was compared between patients selected for adjuvant palbociclib or observation. RESULTS: Between 2017 and 2020, 12 patients underwent a total of 14 operations (14 patient cases) and were selected for adjuvant palbociclib for recurrence prevention. These patients were compared with 14 patients who, since 2010, underwent a total of 20 operations (20 patient cases) and were selected for observation. Histology was primarily dedifferentiated liposarcoma for both groups (observation: 70% [14/20]; adjuvant palbociclib: 64% [9/14]). All patients underwent complete gross resection. Neither age, number of previous surgeries, histologic grade, or Eastern Cooperative Oncology Group (ECOG) performance status differed between groups (p > 0.05 for all). Patients selected for adjuvant palbociclib experienced a longer treatment interval than those selected for observation, although it did not reach statistical significance (20.5 months vs. 13.1 months, p = 0.08, log rank). CONCLUSION: Adjuvant palbociclib may be associated with a prolonged interval between liposarcoma resection and the need for re-resection or other systemic therapy. Palbociclib may be effective in delaying liposarcoma recurrence, and its use for this indication warrants prospective study.

Association between surgical delay and outcomes among patients with invasive cutaneous melanoma.

BACKGROUND: The relationship between surgical delay and outcomes for patients with cutaneous melanoma is understudied. The objectives of this study were to determine the impact of surgical delay on regional nodal involvement and mortality in patients with cutaneous melanoma. METHODS: Retrospective study of patients diagnosed with clinically node-negative invasive cutaneous melanoma from 2004 to 2018. Outcomes included regional lymph node disease and overall survival. Multivariable logistic regression and Cox proportional-hazards models were constructed to adjust for pertinent clinical factors. RESULTS: Of 423,001 patients, 21.8% experienced a surgical delay (≥45 days). These patients were more likely to have nodal involvement (OR1.09; P â€‹= â€‹0.01). Surgical delay (HR1.14; P â€‹< â€‹0.001), Black race (HR1.34; P â€‹= â€‹0.002), and Medicaid (HR1.92; P â€‹< â€‹0.001) were associated with lower survival. Patients treated at academic/research (HR0.87; P â€‹< â€‹0.001) or integrated network cancer programs (HR0.89; P â€‹= â€‹0.001) had improve survival. CONCLUSIONS: Surgical delay was frequent and resulted in higher rates of lymph node involvement and decreased overall survival.

Outcomes of plastic surgical reconstruction in extremity and truncal soft tissue sarcoma: Results from the US Sarcoma Collaborative.

BACKGROUND: This study aimed to define how utilization of plastic surgical reconstruction (PSR) affects perioperative outcomes, locoregional recurrence-free survival (LRRFS), and overall survival (OS) after radical resection of extremity and truncal soft tissue sarcoma (ETSTS). The secondary aim was to determine factors associated with PSR. METHODS: Patients who underwent resection of ETSTS between 2000 and 2016 were identified from a multi-institutional database. PSR was defined as complex primary closure requiring a plastic surgeon, skin graft, or tissue-flap reconstruction. Outcomes included PSR utilization, postoperative complications, LRRFS, and OS. RESULTS: Of 2750 distinct operations, 1060 (38.55%) involved PSR. Tissue-flaps (854, 80.57%) were most commonly utilized. PSR was associated with a higher proportion of R0 resections (83.38% vs. 74.42%, p < 0.001). Tissue-flap PSR was associated with local wound complications (odds ratio: 1.81, confidence interval: 1.21-2.72, p = 0.004). Neither PSR nor postoperative complications were independently associated with LRRFS or OS. High-grade tumors (1.60, 1.13-2.26, p = 0.008) and neoadjuvant radiation (1.66, 1.20-2.30, p = 0.002) were associated with the need for PSR. CONCLUSION: Patients with ETSTS undergoing resection with PSR experienced acceptable rates of complications and a higher rate of negative margins, which were associated with improved LRRFS and OS. High tumor grade and neoadjuvant radiation were associated with requirement of PSR.

Prognostic factors in patients receiving surgery and radiation therapy for retroperitoneal sarcoma: A machine-learning analysis.

BACKGROUND: The addition of radiation therapy to surgery for retroperitoneal sarcoma remains controversial. Improved patient selection may help identify optimal candidates for multimodality treatment. The aim of this analysis was to define prognostic factors among patients who receive radiation therapy and surgery to aid in patient selection for multimodal therapy. METHODS: Patients who received radiation therapy and underwent curative-intent resection for retroperitoneal sarcoma between 2004 and 2016 were identified from a national cohort in the United States (National Cancer Database). A machine-based classification and regression tree model was used to generate similar groups of patients relative to overall survival based on preoperative factors. RESULTS: A total of 1,443 patients received radiation therapy in addition to surgery. Median age was 61 years old and 55.0% were female. Most patients (66%) received care at an academic or integrated network cancer program. With a median follow-up of 84 months, receipt of radiation therapy was not associated with improved overall survival (P = .81). Classification and regression tree analysis revealed a significant association between overall survival and American Joint Committee on Cancer stage group, age, tumor histology, and Charlson comorbidity score. Application of these parameters via machine learning stratified patients into 5 cohorts with distinct survival outcomes. In the most favorable cohort (Cohort 1: American Joint Committee on Cancer stage group ≤II, age ≤61, histology including fibrosarcoma, well differentiated liposarcoma, myxoid liposarcoma, and leiomyosarcoma), the 5-year overall survival was 81.7% and median overall survival was not reached; in the least favorable cohort (Cohort 6: American Joint Committee on Cancer stage group >II, age >68) where the 5-year survival was 41.3% and median overall survival was 45.2 months (P < .001 versus Cohort 1). CONCLUSION: In the absence of a defined survival benefit, patients with advanced American Joint Committee on Cancer stage group, older age, and medical comorbidities have relatively unfavorable overall survival after combined modality therapy and therefore stand the least to gain from the addition of radiation therapy to surgery. In contrast, younger patients with good performance status and retroperitoneal sarcoma histologies with a higher propensity for local recurrence may have the greatest opportunity to benefit from radiation therapy.

The Implications of an Unplanned Sarcoma Excision (the "Whoops" Operation).

In this review, the risk factors of an unplanned excision of soft-tissue sarcoma and the implications of non-oncologic resection are discussed. Although soft-tissue sarcoma remains a rare disease, many studies have shown the deleterious effects of unplanned excision, including decreased recurrence-free survival and increased morbidity. Once discovered, sarcomas should be referred to expert centers for further management, which often entails re-excision, radiation, and/or chemotherapy treatment. Although much still needs to be learned about this complex disease, a multidisciplinary approach including surgeons, medical oncologists, radiologists, and pathologists is paramount to its successful treatment.

In situ hybridization to detect DNA amplification in extracellular vesicles.

EVs have emerged as an important component in tumour initiation, progression and metastasis. Although notable progresses have been made, the detection of EV cargoes remain significantly challenging for researchers to practically use; faster and more convenient methods are required to validate the EV cargoes, especially as biomarkers. Here we show, the possibility of examining embedded EVs as substrates to be used for detecting DNA amplification through ultrasensitive in situ hybridization (ISH). This methodology allows the visualization of DNA targets in a more direct manner, without time consuming optimization steps or particular expertise. Additionally, formalin-fixed paraffin-embedded (FFPE) blocks of EVs allows long-term preservation of samples, permitting future studies. We report here: (i) the successful isolation of EVs from liposarcoma tissues; (ii) the EV embedding in FFPE blocks (iii) the successful selective, specific ultrasensitive ISH examination of EVs derived from tissues, cell line, and sera; (iv) and the detection of MDM2 DNA amplification in EVs from liposarcoma tissues, cell lines and sera. Ultrasensitive ISH on EVs would enable cargo study while the application of ISH to serum EVs, could represent a possible novel methodology for diagnostic confirmation. Modification of probes may enable researchers to detect targets and specific DNA alterations directly in tumour EVs, thereby facilitating detection, diagnosis, and improved understanding of tumour biology relevant to many cancer types.

Extraskeletal myxoid chondrosarcoma: Clinicopathological features and outcomes from the United States sarcoma collaborative database.

BACKGROUNDS AND OBJECTIVES: This investigation described clinicopathological features and outcomes of extraskeletal myxoid chondrosarcoma (EMC) patients. METHODS: EMC patients were identified from the United States Sarcoma Collaborative database between 2000 and 2016. Overall survival (OS) and recurrence-free survival (RFS) were calculated, and prognostic factors were analyzed. RESULTS: Sixty individuals with a mean age of 55 years were included, and 65.0% (n = 39) were male. 73.3% (n = 44) had a primary tumor. A total of 41.6% (n = 25) developed tumor relapse following resection. The locoregional recurrence rate was 30.0% (n = 18/60), and mean follow-up was 42.7 months. The 5-year OS was 71.0%, while the 5-year RFS was 41.4%. On multivariate analysis for all EMC, chemotherapy (hazard ratio [HR], 6.054; 95% confidence interval [CI], 1.33-27.7; p = 0.020) and radiation (HR, 5.07, 95% CI, 1.3-20.1; p = 0.021) were independently predictive of a worse RFS. Among patients with primary EMC only, the 5-year OS was 85.3%, with a 30.0% (n = 12) locoregional recurrence rate, though no significant prognostic factors were identified. CONCLUSIONS: Long-term survival with EMC is probable, however there exists a high incidence of locoregional recurrence. While chemotherapy and radiation were associated with a worse RFS, these findings were likely confounded by recurrent disease as significance was lost in the primary EMC-only subset.

The Role of AKT in Soft Tissue Sarcoma: Review and Insights.

Soft tissue sarcomas (STS) are a biologically diverse group of mesenchymal tumors that predominantly exhibit a poor prognosis. Surgical resection is considered the mainstay of treatment and provides the only chance for long-term survival. However, some patients present with locally advanced, unresectable disease, and for those who are able to undergo resection, tumor recurrence occurs in over half of patients. In addition, the efficacy of conventional systemic therapies remains dismal. The serine/threonine kinase AKT pathway is one of the most frequently aberrantly activated signaling pathways that has been verified in many types of human cancer. Dysregulation of the AKT cascade is known to result in tumorigenesis and aggressive clinical behavior for many tumor types, including STS. EGFRs, with its downstream effectors, PI3K and protein kinase B (AKT)/mTOR, have been investigated for decades as promising targets for the treatment of STS, but significant challenges remain and the prognosis of patients with advanced STS has not improved in over two decades. In this review, we will first describe the AKT pathway and its role in STS tumor biology and then discuss the current challenges in targeting the AKT pathway to treat patients with advanced sarcoma.

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.

Targetable Pathways in the Treatment of Retroperitoneal Liposarcoma.

Liposarcoma (LPS) is the most prevalent soft tissue sarcoma histological subtype. When it occurs in the abdomen the overall survival rate is as low as 10% at 10 years and is fraught with high rates of recurrence, particularly for the more aggressive dedifferentiated subtype. Surgery remains the mainstay of treatment. Systemic therapies for the treatment of metastatic or unresectable disease have low response rates. Deep understanding of well-differentiated and de-differentiated LPS (WDLPS and DDLPS, respectively) oncologic drivers is necessary for the development of new efficacious targeted therapies for the management of this disease. This review discusses the current treatments under evaluation for retroperitoneal DDLPS and the potential targetable pathways in DDLPS.

Extremity Soft Tissue Sarcoma: A Multi-Institutional Validation of Prognostic Nomograms.

BACKGROUND: Prognostic nomograms for patients with resected extremity soft tissue sarcoma (STS) include the Sarculator and Memorial Sloan Kettering (MSKCC) nomograms. We sought to validate these two nomograms within a large, modern, multi-institutional cohort of resected primary extremity STS patients. METHODS: Resected primary extremity STS patients from 2000 to 2017 were identified across nine high-volume U.S. institutions. Predicted 5- and 10-year overall survival (OS) and distant metastases cumulative incidence (DMCI), and 4-, 8-, and 12-year disease-specific survival (DSS) were calculated with Sarculator and MSKCC nomograms, respectively. Predicted survival probabilities stratified in quintiles were compared in calibration plots to observed survival assessed by Kaplan-Meier estimates. Cumulative incidence was estimated for DMCI. Harrell's concordance index (C-index) assessed discriminative ability of nomograms. RESULTS: A total of 1326 patients underwent resection of primary extremity STS. Common histologies included: undifferentiated pleomorphic sarcoma (35%), fibrosarcoma (13%), and leiomyosarcoma (9%). Median tumor size was 8.0 cm (IQR 4.5-13.0). Tumor grade distribution was: Grade 1 (13%), Grade 2 (9%), Grade 3 (78%). Median OS was 172 months, with estimated 5- and 10-year OS of 70% and 58%. C-indices for 5- and 10-year OS (Sarculator) were 0.72 (95% CI 0.70-0.75) and 0.73 (95% CI 0.70-0.75), and 0.72 (95% CI 0.69-0.75) for 5- and 10-year DMCI. C-indices for 4-, 8-, and 12-year DSS (MSKCC) were 0.71 (95% CI 0.68-0.75). Calibration plots showed good prognostication across all outcomes. CONCLUSIONS: Sarculator and MSKCC nomograms demonstrated good prognostic ability for survival and recurrence outcomes in a modern, multi-institutional validation cohort of resected primary extremity STS patients. External validation of these nomograms supports their ongoing incorporation into clinical practice.