Retroperitoneal sarcoma: a 10-year follow-up analysis using hospital-based cancer registry data in Japan.

OBJECTIVES: We sought clinical characteristics, survival outcomes, and prognostic factors for overall survival of retroperitoneal sarcoma in Japan. METHODS: A Japanese hospital-based cancer registry database with a pivotal 10-year follow-up was used to identify and enroll patients, registered from 106 institutions, diagnosed with retroperitoneal sarcoma in 2008-2009. Treating hospitals were divided by hospital care volume; high-volume hospitals and low-volume hospitals were defined as ≥ 4 and < 4 cases/year, respectively. RESULTS: A total of 91 men and 97 women were included, with a median age of 64 years. The most common histological type was liposarcoma in 101 patients, followed by leiomyosarcoma in 38 patients. The 5-year and 10-year overall survival rates were 44.1 and 28.3%. The majority of patients (n = 152, 80.9%) were treated at low-volume hospitals. High-volume hospital patients had higher 10-year overall survival rates than low-volume hospital patients (51.2% vs 23.2%, P = 0.026). Multivariate analysis revealed age over 60 years, treatment in low-volume hospitals and chemotherapy were independent predictors of unfavorable survival while treatment with surgery was an independent predictor of favorable survival. CONCLUSIONS: The possibility of surgical removal was suggested to be the most important prognostic factor for retroperitoneal sarcoma. Better survival was shown in patients treated at high-volume hospitals in our series.

Pediatric retroperitoneal non-organ-originated malignancies: An analysis based on SEER database.

Retroperitoneal non-organ-originated malignancies are rare pediatric tumors with challenging diagnosis and treatment. The present study aimed to analyze the clinicopathological characteristics, treatment, and prognosis of retroperitoneal non-organ-originated malignancies. In the study, we included the pathological diagnosis of pediatric retroperitoneal non-organ-originated malignant tumors between 2000 to 2019 through the updated Surveillance, Epidemiology, and End Results database. We use the Kaplan-Meier survival curve to calculate the overall survival (OS) and cancer-specific survival (CSS). The risk of all-cause death and disease-specific death were analyzed using Cox proportional hazard regression model and Fine-and-Grey competitive hazard model, respectively. In the study, a total of 443 pediatric retroperitoneal non-organ-originated malignancies were included. Of them, only 22.3% of patients had no metastatic disease, 42.9% had distant metastasis and 34.8% had locally advanced diseases. The primary pathological tumor was neuroblastoma followed by germ cell tumor. The overall 10-year OS and CSS were 70.7% and 73.1%, respectively, and the 10-year OS and CSS of metastatic diseases were 54.4% and 56.6%, respectively. Older children, worse tumor stage at diagnosis, incomplete resection, and prolonged time from diagnosis to treatment were significantly associated with worse survival outcomes. Radiotherapy and chemotherapy did not significantly improve the prognosis of patients without complete tumor resection. The study indicated that most pediatric retroperitoneal non-organ-originated malignancies diagnosed with metastatic diseases have plagued treatment. Radiotherapy and chemotherapy are the main treatment methods for children unable to undergo complete surgical treatment. However, these treatments do not reach the same therapeutic effect as complete tumor resection after early diagnosis. Hence, early diagnosis and surgery for complete tumor resection are of utmost importance.

Incidence, Treatment and Outcome of Patients with Retroperitoneal Soft-Tissue Sarcoma in Switzerland 2005-2015: A Population-Based Analysis.

BACKGROUND: Reports on the epidemiology and mortality of retroperitoneal soft tissue sarcoma (RSTS) in Switzerland are scarce. This study investigates the incidence and outcomes of surgically treated RSTS inpatients in Switzerland depending on the hospital type and size. METHODS: Data from the Swiss Federal Statistical Office were used to conduct a retrospective analysis of all RSTS inpatients and hospitalizations in Switzerland between 2005 and 2015. RSTS was identified by the code C48.x of the International Classification of Diseases (ICD-10). Sarcoma centers were identified by the annual total number of sarcoma patients (> 50 patients/year). The analysis of yearly incidence, age distribution as well as in-hospital complication and mortality was performed for non- and surgical-treated patients. A centralization of treating sarcoma patients was analyzed by the trend of hospitalizations in sarcoma centers and high-volume hospitals. RESULTS: During 2005-2015, 2.801 hospitalizations (1651 patients) were admitted to Swiss hospitals with the primary diagnosis of a RSTS. The yearly number of RSTS patients and the incidence (1.91/100.000) stayed constant within these 11 years. There were five sarcoma centers. We saw a clear trend of RSTS patients being treated (especially surgically) in centers over the 11 years. The complication rate of surgical-treated patients was higher in sarcoma centers (55% vs. 40%), though the overall mortality rate was lower (3.2% vs. 9.1%). CONCLUSION: Centralization of RSTS treatment to certified sarcoma centers leads to a lower overall mortality rate and thus is highly recommended.

Percentage of Teratoma in Orchiectomy and Risk of Retroperitoneal Teratoma at the Time of Postchemotherapy Retroperitoneal Lymph Node Dissection in Germ Cell Tumors.

PURPOSE: Presence of teratoma in the orchiectomy and residual retroperitoneal mass size are known predictors of finding teratoma during postchemotherapy retroperitoneal lymph node dissection (PC-RPLND). We sought to determine if the percentage of teratoma in the orchiectomy specimen could better stratify the risk of teratoma in the retroperitoneum. MATERIALS AND METHODS: The Indiana University Testis Cancer Database was reviewed to identify patients who underwent PC-RPLND for nonseminomatous germ cell tumors from 2010 to 2018. A logistic regression model was fit to predict the presence of retroperitoneal teratoma using teratoma and yolk sac tumor in the orchiectomy, residual mass size and log transformed values of prechemotherapy alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin. The study cohort was split into 60% training and 40% validation sets using 200 bootstraps. A predictive nomogram was developed for predicting teratoma in the retroperitoneum. RESULTS: A total of 422 men were included. Presence of teratoma in the orchiectomy (OR 1.02, p <0.001), residual mass size (OR 1.16, p <0.001) and log transformed prechemotherapy AFP (OR 1.12, p=0.002) were predictive factors for having teratoma in the retroperitoneum. The C-statistic using this model demonstrated a predictive ability of 0.77. Training set C-statistic was 0.78 compared to 0.75 for the validation set. A nomogram was developed to aid in clinical utility. CONCLUSIONS: The model better predicts patients at higher risk for teratoma in the retroperitoneum following chemotherapy, which can aid in a more informed referral for surgical resection.

Risk Assessment of Visceral Sarcomas: A Comparative Study of 2698 Cases from the SEER Database.

Soft tissue sarcomas arising in visceral organs are rare and lack validated tumor-staging protocols. Clinicopathologic features and clinical outcomes of 2698 visceral sarcomas identified in the Surveillance, Epidemiology, and End Results Program (SEER) database were compared with sarcomas arising in the extremities/trunk (n = 10,237) or retroperitoneum (n = 1067) using standard statistical techniques. Important prognostic criteria for visceral sarcomas, as in other anatomic sites, included tumor size, histologic grade, and presence of metastatic disease. After adjustment for pertinent confounding factors, visceral sarcomas showed cancer-specific survival rates similar to those arising in the retroperitoneum but had worse outcomes than sarcomas in the extremities/trunk. Therefore, the prognostic performance of two different staging algorithms for retroperitoneal sarcomas was evaluated for their use in staging sarcomas of visceral organs. The current AJCC 8th edition and the recently derived Vanderbilt system for staging retroperitoneal sarcoma both showed adequate discrimination, as assessed by multiple clinical concordance indices, and no evidence of miscalibration. Therefore, the authors concluded that previously validated staging systems for retroperitoneal sarcomas based on conventional prognostic factors (histologic grade, tumor size, and presence of metastatic disease) are applicable to visceral sarcomas and should be incorporated into the next edition of the AJCC Cancer Staging Manual.

Primary localized retroperitoneal sarcomas: report from Slovenian sarcoma referral center.

BACKGROUND: Sarcoma patients should be treated in high volume referral sarcoma centers. Compartmental resection is proposed as the best treatment option in retroperitoneal sarcoma patients. METHODS: Institute of Oncology Ljubljana is the only referral sarcoma center in Slovenia. Having a population of 2.1 million poses a unique situation. We manage all sarcoma patients in the country and operate on patients with soft tissue tumors of extremities, trunk, and abdomen. Data for all consecutive patients surgically treated from January 1999 to December 2018 for primary localized retroperitoneal sarcoma was extracted from a prospective surgical database. Data about the incidence of sarcoma patients in Slovenia was extracted from the Cancer Registry of Republic of Slovenia. Clinicopathologic variables and the outcome were analyzed. RESULTS: In total, 89 patients were included in the study. Median age was 62 years. Dedifferentiated liposarcoma was the most common histology (38.2%). Median tumor size was 21 cm. Compartmental resection was performed in 47.2% (42/89). Postoperative complication grade 3a or higher according to Clavien-Dindo classification had 30.3% (27/89) of patients. The 30-day and 90-day mortality rate was 2.2% and 5.6%. Median follow-up was 62.1 months. Corresponding 5-year overall survival was 67.2%, 5-year disease-specific survival was 72.6%, and 5-year local recurrence-free survival was 81.5%, respectively. CONCLUSION: Results from our institution show that referral sarcoma centers may achieve very good results in management of retroperitoneal sarcoma patients, despite not meeting the criteria for high volume hospitals, as long as they have multidisciplinary team, appropriate facilities, and expertise.

Prognostic factors of metastatic myxoid liposarcoma.

BACKGROUND: Myxoid liposarcoma (MLS) has the tendency to metastasize extrapulmonary. Although prognostic factors at the initial diagnosis of MLS have been reported, those at diagnosis of metastasis remain unclear. The purpose of this study was to investigate the prognostic factors for disease-specific survival at the initial diagnosis of metastasis. METHODS: This retrospective observational study was conducted at three cancer centers and two university hospitals in Japan. Of 274 MLS patients pathologically diagnosed between 2001 and 2015, 48 metastatic patients were examined. RESULTS: Lung metastases were detected in nine patients (18.8%) and extrapulmonary metastases in 45 (93.8%). Interval from primary diagnosis to the first metastasis was significantly shorter in patients with lung metastases than without (p = 0.007). Median disease-specific survival after diagnosis of metastases was 52.5 months in all patients. In multivariable analysis, liver metastasis (hazard ratio (HR), 2.71 [95% confidence interval (CI), 1.00-7.09]) and no evidence of disease (NED) achieved by radical treatment (resection with or without radiation therapy, or radiation therapy ≥60 Gy) or semi-radical (radiation therapy ≥40 Gy) treatment were significantly related to survival (HR, 0.36; 95%CI [0.13-0.95]). The number of metastases (odds ratio (OR), 0.44; 95%CI [0.25-0.78]) and abdominal/retroperitoneal metastases (OR, 0.09; 95%CI [0.008-0.95]) were the significant inhibitory factors of achieving NED. CONCLUSIONS: This is the first study to statistically demonstrate the importance of achieving NED with surgical resection or radiation therapy for longer survival in metastatic MLS patients. As number of metastases was a significant factor for achieving NED, early detection of metastases might be important.

Laparoscopic Resection of Residual Retroperitoneal Tumor Mass in Advanced Nonseminomatous Testicular Germ Cell Tumors; a Feasible and Safe Oncological Procedure.

Ten-year oncological experience of the University Medical Center Groningen with conventional laparotomy (C-RRRTM) and laparoscopy (L-RRRTM) is described concerning resection of residual retroperitoneal tumor masses (RRTM) in a large series of patients with advanced nonseminomatous testicular germ cell tumors (NSTGCT). 150 consecutive patients with disseminated NSTGCT required adjunctive surgery after combination chemotherapy. L-RRRTM was scheduled in 89 and C-RRRTM in 61 patients. Median residual tumor diameter was 20 mm in the L-RRRTM versus 42 mm in the C-RRRTM group (p < 0.001). Conversion rate was 15% in the L-RRRTM group. Perioperative complications occurred in 5 patients (6%) in the L-RRRTM and 7 (12%, NS) in the C-RRRTM group. Median duration of L-RRRTM was 156 minutes vs. 221 minutes for C-RRRTM (p < 0.001). 17/89 patients in the L-RRRTM group had postoperative complications versus 18/61 patients in the C-RRRTM group (NS). Median postoperative stay in the L-RRRTM group was 2 vs. 6 days in the C-RRRTM group (p < 0.001). During a median follow-up of 79 months, 27 patients had recurrences: 8 (9%) in the L-RRRTM group and 19 (31%) in the C-RRRTM group (p < 0.001). Laparoscopic resection of RRTM for advanced NSTGCT is feasible and an oncologically safe option in appropriately selected patients.

Update in pelvic and retroperitoneal sarcoma management: The role of compartment surgery. / Actualización en el manejo de sarcomas retroperitoneales y pélvicos; el papel de la cirugía compartimental.

Surgery for retroperitoneal sarcomas should be "en bloc" compartmental, which involves resection of unaffected organs. Its upfront use is key, providing a high percentage of resections with negative margins, resulting in a better local control and increased survival in many patients. Preservation of organs should be done in an individualized manner, especially in the pelvic location, and adapted to the histological aggressiveness of the tumor. Preoperative biopsy is able to establish the diagnosis of sarcoma subtype and consequently an adequate perioperative strategy. These patients should be managed by expert surgeons at referral centers with multidisciplinary units and oncology committees. The use of chemotherapy and radiotherapy is not yet well defined, so it is only recommended at referral centers with clinical trials. Currently, this is the only option to offer the best morbidity and mortality rates, as well as possible improvements in the survival of these patients.

Recurrence patterns after resection of retroperitoneal sarcomas: An eight-institution study from the US Sarcoma Collaborative.

BACKGROUND AND OBJECTIVES: Resection of primary retroperitoneal sarcomas (RPS) has a high incidence of recurrence. This study aims to identify patterns of recurrence and its impact on overall survival. METHODS: Adult patients with primary retroperitoneal soft tissue sarcomas who underwent resection in 2000-2016 at eight institutions of the US Sarcoma Collaborative were evaluated. RESULTS: Four hundred and ninety-eight patients were analyzed, with 56.2% (280 of 498) having recurrences. There were 433 recurrences (1-8) in 280 patients with 126 (25.3%) being locoregional, 82 (16.5%) distant, and 72 (14.5%) both locoregional and distant. Multivariate analyses revealed the following: Patient age P = .0002), tumor grade (P = .02), local recurrence (P = .0003) and distant recurrence (P < .0001) were predictors of disease-specific survival. The 1-, 3-, and 5-year survival rate for patients who recurred vs not was 89.6% (standard error [SE] 1.9) vs 93.5% (1.8), 66.0% (3.2) vs 88.4% (2.6), and 51.8% (3.6) vs 83.9% (3.3), respectively, P < .0001. Median survival was 5.3 years for the recurrence vs 11.3+ years for the no recurrence group (P < .0001). Median survival from the time of recurrence was 2.5 years. CONCLUSIONS: Recurrence after resection of RPS occurs in more than half of patients independently of resection status or perioperative chemotherapy and is equally distributed between locoregional and distant sites. Recurrence is primarily related to tumor biology and is associated with a significant decrease in overall survival.

Impact of Teratoma on the Cumulative Incidence of Disease-Related Death in Patients With Advanced Germ Cell Tumors.

PURPOSE: In men with metastatic germ cell tumors (GCTs), risk-directed treatment is determined, in part, by a distinction between seminoma and nonseminomatous GCT (NSGCT). The importance of NSGCT cell type is uncertain. We evaluated the long-term impact of teratoma on survival in patients with NSGCT. METHODS: Prechemotherapy, primary tumors from patients who received platinum-based chemotherapy were studied, and the histology was confirmed by a genitourinary pathologist. The cumulative incidence of disease-related death (CIDD) was the primary end point, and a competing-risk analysis was performed. RESULTS: Tumors were available from 232 patients, including 193 with NSGCT. An element of teratoma was present in 82 NSGCT primary tumors (42%). With a median follow-up of 17 years (range, 0.3 to 35 years), 58 patients with NSGCT died, 47 as a result of GCT and 11 as a result of other causes. Most GCT deaths occurred within the first 5 years and were associated with pretreatment risk status (P < .001). Death as a result of other causes rose steadily after 15 years and was not associated with risk status (P = .66). A higher CIDD was observed in patients who had NSGCT with teratoma than those with NSGCT without teratoma and seminoma (5-year CIDD rate, 27.4%, 17.4%, and 10.3%, respectively; P = .03). A higher CIDD was observed in patients who had NSGCT with mature teratoma compared with those with either NSGCT with immature teratoma or NSGCT without teratoma (5-year CIDD rate, 38.1%, 19.9%, and 17.4%, respectively; P = .01). CONCLUSION: The presence of teratoma, particularly mature teratoma, in an NSGCT primary tumor is associated with a higher CIDD, consistent with the hypothesis that differentiation is associated with adverse outcomes. Death as a result of non-GCT causes is not associated with risk status and must be separated from GCT death when evaluating long-term survival.

A systematic review of population-based studies examining outcomes in primary retroperitoneal sarcoma surgery.

Retroperitoneal sarcomas (RPS) are rare mesenchymal tumours. Their rarity challenges our ability to understand expected outcomes. The aim of this systematic review was to examine 30-day morbidity and mortality, overall survival rates and prognostic predictors from population-based studies for patients undergoing curative resection for primary RPS. A systematic literature review of EMBASE, MEDLINE, PUBMED and the Cochrane library was performed using PRISMA for population-based studies reporting from nationally registered databases on primary RPS surgical resections in adults. The main outcomes evaluated were 30-day morbidity and mortality and overall survival rates. The use of additional treatment modalities and predictors of overall survival were also examined. Fourteen studies (n = 12 834 patients) reporting from 3 national databases, (Surveillance, Epidemiology and End Results (SEER), the United States National Cancer Database (US NCDB) and the American College of Surgeons' National Surgical Quality Improvement Program (ACS NSQIP)) were analysed. The reported overall 30-day morbidity and mortality were 23% (n = 191/846) and 3% (n = 278/10 181) respectively. Reported use of perioperative radiotherapy was 28%. No study reported loco-regional recurrence rates. Overall reported 5-year survival ranged from 52% to 62%. Independent predictors of overall survival were age of the patient, resection margin, tumour grade and size, histological subtype and receipt of radiotherapy. This review of population-based data demonstrated relatively low 30-day morbidity rates in patients undergoing curative surgical resections for primary RPS. Thirty-day mortality rates were similar to other abdominal tumour groups. There remains a paucity of data reporting recurrence rates, however 5-year survival rates ranged from 52 to 62%.

Maximum standardized uptake value on 18F-fluorodeoxyglucose positron emission tomography/computed tomography improves outcome prediction in retroperitoneal liposarcoma.

While 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has been investigated in extremity sarcomas, there is no evidence on its usefulness in retroperitoneal sarcoma. This study was designed to evaluate the usefulness of 18F-FDG PET/CT in predicting aggressiveness of retroperitoneal liposarcoma. Patients experienced surgery for retroperitoneal liposarcoma from November 2007 to February 2018 and underwent preoperative 18F-FDG PET/CT were included. Preoperative maximum standardized uptake value (SUVmax) was calculated. To evaluate the predictability of SUVmax for Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) grade 3, receiver operating characteristics (ROC) curve analysis was performed. To analyze whether SUVmax can be a risk factor for prognosis, multivariable Cox regression was performed including potential risk factors regarding operation and histopathology. A total of 133 patients were included. ROC curve showed area under the curve of 0.877 (P < 0.001), with a cut-off point of 4.5 SUVmax showing 85.7% sensitivity and 78.3% specificity. Cox analyses showed that SUVmax > 4.5 was a significant factor for recurrence-free survival (HR = 2.148, CI 1.301-3.546, P = 0.003) and overall survival (HR = 5.052, CI 1.854-13.766, P = 0.002). SUVmax is highly predictive of FNCLCC grade 3 and SUVmax > 4.5 can be used as a prognostic factor before obtaining the histopathology.

Role of nutritional status in the early postoperative prognosis of patients operated for retroperitoneal liposarcoma (RLS): A single center experience.

PURPOSE: To assess the nutritional status and its role in the outcome of patients operated for retroperitoneal liposarcoma (RLS). MATERIAL AND METHODS: Retrospective study on consecutive patients operated with en bloc compartment resection for primary or local recurrence of RLS between 2016 and 2017. Preoperative nutritional and laboratory assessment comprising serum albumin, serum transthyretin, orosomucoid, and CRP was systematically performed. The following preoperative parameters were analysed: weight, body mass index (BMI), significant weight loss (>5% in one month and/or >10% in 6 months), serum albumin, transthyretin, CRP, orosomucoid. PINI (prognostic inflammatory and nutritional index) was calculated. RESULTS: There were 40 patients operated for RLS: 22 women and 18 men with a median age of 61 years (34-90). Median tumour was 280 mm (80-530). Median preoperative BMI was 24.8 (18-42) and median postoperative BMI was 23 (17.8-44). Twenty-one patients (52.5%) were considered to be malnourished: 3 with biological signs of malnutrition and 18 with weight loss. Eleven (47.6%) in the group of malnourished patients and 4 (26.3%) in the group with satisfactory nutritional status developed postoperative complications (p = 0.042). A PINI score>1 was related to significantly longer hospitalisation time 21.8 days (10-58) in comparison with 14.9 [9-30] in patients with PINI < 1, p = 0.003. CONCLUSIONS: The malnourished patients with RLS experienced more postoperative complications and longer hospitalisation. Nutritional status and biological markers contribute to the global management of RLS with improved postoperative behaviour including fewer complications and shorter hospitalisation. A prospective larger study with longer follow-up is necessary to refine these results.

Regionalization of Retroperitoneal Sarcoma Surgery to High-Volume Hospitals: Missed Opportunities for Outcome Improvement.

PURPOSE: Surgery continues to be the dominant therapy for the management of retroperitoneal soft-tissue sarcoma (RPS). Many groups advocate performing these resections at high-volume hospitals (HVHs), given their complexity. We therefore sought to explore whether RPS surgery has indeed begun to regionalize to HVHs in the same manner as pancreatic cancer (PC) surgery during the last decade. METHODS: We identified 70,763 patients who underwent surgical resection for RPS or PC using the National Cancer Database (2004 to 2015). Patients were stratified by hospital surgical volume. We performed an adjusted time trend analysis to compare trends in performance of surgery at HVHs for RPS versus PC. Multivariable logistic analyses were then performed, controlling for covariables, to elucidate relationships between patient-, hospital-, and treatment-related variables that may contribute to these observed trends. RESULTS: Only 9.6% of patients underwent RPS surgery at HVHs. During this time period, the odds ratio of undergoing RPS compared with pancreatectomy at HVHs was 0.65 ( P < .05). Time trend analysis estimated that whereas both procedures are regionalizing, the rate of RPS regionalization grew at 30.5% of the rate of PC (1.017 v 1.056; P < .001) and remained consistent after using several hospital volume thresholds and hospital volume as a continuous variable. CONCLUSION: Results from this retrospective multi-institutional analysis uncovered a lag in the regionalization of surgery for RPS compared with PC surgery. These findings reinforce the call to regionalize surgery for RPS to HVHs in a manner that is similar to that of other procedures in complex cancer surgery.

Risk factors of early recurrence in retroperitoneal liposarcoma. / Factores de riesgo implicados en la recurrencia precoz del liposarcoma retroperitoneal.

INTRODUCTION: The aim of this study is to identify factors associated to recurrence and survival in primary retroperitoneal liposarcomas. METHODS: Prospective database of 35 patients with primary retroperitoneal liposarcoma treated 2004-2015 were retrospectively analyzed. Exclusion criteria were recurrent and metastatic tumors. Overall survival (OS) and disease-free survival were reviewed. Patient data were compared between patients with or without recurrence within 12 months after surgery. Risk factors were determined using logistic regression analysis. RESULTS: Five-year OS was 61.1%. One and three-year disease-free survival were 68.6% and 17.1% respectively. OS in the early recurrence group was 36.4 months compared with 43.2 months in the group without early recurrence (P=.011). Early recurrence was associated with a reduction in OS (HR=4.05; CI95%: 1.27-12.96; P=.018). Multifocality and microscopic positive margins R1 were associated with early recurrence. Histologic subtype, margin of resection, histologic grade and multifocality were factors associated with recurrence. Contiguously involved organ resection had a beneficial effect on early recurrence and was associated with an increase in disease-free survival and OS. Adjuvant treatments had no protective effect on recurrence. CONCLUSIONS: This study underlines the crucial role aggressive surgical approach in retroperitoneal Liposarcoma treatment, especially in those patients with histological characteristics that adversely the prognosis.

Unsupervised versus Supervised Identification of Prognostic Factors in Patients with Localized Retroperitoneal Sarcoma: A Data Clustering and Mahalanobis Distance Approach.

The aim of this report is to unveil specific prognostic factors for retroperitoneal sarcoma (RPS) patients by univariate and multivariate statistical techniques. A phase I-II study on localized RPS treated with high-dose ifosfamide and radiotherapy followed by surgery (ISG-STS 0303 protocol) demonstrated that chemo/radiotherapy was safe and increased the 3-year relapse-free survival (RFS) with respect to historical controls. Of 70 patients, twenty-six developed local, 10 distant, and 5 combined relapse. Median disease-free interval (DFI) was 29.47 months. According to a discriminant function analysis, DFI, histology, relapse pattern, and the first treatment approach at relapse had a statistically significant prognostic impact. Based on scientific literature and clinical expertise, clinicopathological data were analyzed using both a supervised and an unsupervised classification method to predict the prognosis, with similar sample sizes (66 and 65, resp., in casewise approach and 70 in mean-substitution one). This is the first attempt to predict patients' prognosis by means of multivariate statistics, and in this light, it looks noticable that (i) some clinical data have a well-defined prognostic value, (ii) the unsupervised model produced comparable results with respect to the supervised one, and (iii) the appropriate combination of both models appears fruitful and easily extensible to different clinical contexts.

Anterior Approach to En Bloc Resection in Left-Sided Retroperitoneal Sarcoma with Adjacent Organ Involvement: A Study of 25 Patients in a Single Center.

BACKGROUND There is no standard surgical approach for the management of retroperitoneal sarcoma. The aim of this clinical study was to describe the experience of an anterior approach to en bloc resection in left-sided retroperitoneal sarcoma with adjacent organ involvement. MATERIAL AND METHODS This retrospective clinical study included 25 patients who were diagnosed with left-sided retroperitoneal sarcoma and underwent tumor resection at a single center between May 2012 and July 2017. All patients had tumors that were adjacent to the left colon, pancreas, left kidney, left adrenal gland, and psoas major; some of the tumors were adjacent to the diaphragm, stomach, and small intestine. An anterior approach was used to remove the left-sided retroperitoneal tumor with the adhesive organs en bloc, an approach that is described in detail. The value of this surgical approach was evaluated based on the histopathological findings, postoperative complications, and patient follow-up. RESULTS The median number of resected organs, in addition to the retroperitoneal tumor, was 8 (range, 6-10). Complete macroscopic tumor resection was achieved in 23 cases (92%). Twenty-four patients (96%) had tumor infiltration of at least one organ or the surrounding fat. Three patients (12%) experienced Grade III and IV postoperative morbidities. The one-year disease-free survival rate was 91.3% among patients with macroscopically complete resections. The one-year overall survival rate was 83.2%. CONCLUSIONS In selected patients, left-sided retroperitoneal sarcoma associated with local organ involvement can be surgically managed using an anterior approach with en bloc resection of adjacent organs.