UNASSIGNED: Intraabdominal and retroperitoneal leiomyosarcomas are rare cancers, which cause significant morbidity and mortality. Symptoms, treatment and follow up differs from other cancers, and proper diagnosis and treatment of intraabdominal and retroperitoneal leiomyosarcomas is of utmost importance. We performed a systematic review to collect and summarize available evidence for diagnosis and treatment for these tumours.
UNASSIGNED: We performed a systematic literature search of Pubmed from the earliest entry possible, until January 2021. Our search phrase was (((((colon) OR (rectum)) OR (intestine)) OR (abdomen)) OR (retroperitoneum)) AND (leiomyosarcoma). All hits were evaluated by two of the authors.
UNASSIGNED: Our predefined search identified 1983 hits, we selected 218 hits and retrieved full-text copies of these. 144 studies were included in the review.
UNASSIGNED: This review summarizes the current knowledge and evidence on non-uterine abdominal and retroperitoneal leiomyosarcomas. The review has revealed a lack of high-quality evidence, and randomized clinical trials. There is a great need for more substantial and high-quality research in the area of leiomyosarcomas of the abdomen and retroperitoneum.
UNASSIGNED: PROSPERO, identifier, CRD42023480527.

OBJECTIVE: Anthracycline-based chemotherapies including doxorubicin monotherapy are recommended in major guidelines for patients with advanced or metastatic retroperitoneal sarcoma (RPS); however, few studies have reported the outcomes of doxorubicin monotherapy for these patients. We herein investigated the oncological efficacy and safety of doxorubicin monotherapy for patients with advanced or metastatic RPS in real-world clinical practice.
METHODS: Sixteen patients diagnosed with advanced or metastatic retroperitoneal sarcoma, receiving doxorubicin monotherapy as first-line treatment between February 2017 and March 2023 at our Institution were analyzed. Response rate, progression-free survival (PFS) periods, overall survival (OS) period, and adverse event (AE) profiles were retrospectively investigated.
RESULTS: The median age of patients was 69.5 years. Best responses to doxorubicin were as follows: complete response, 0 patients (0.0%); partial response, 3 (18.8%); stable disease, 9 (56.3%); and progressive disease, 4 (25.0%). The objective response rate and disease control rate were 18.8 and 75.0%, respectively. During the observation period (median, 22 months, range=2-53 months), median PFS and OS periods were 8.0 and 24.0 months, respectively. The following AEs Grade ≥3 occurred: neutropenia in 14 patients (87.5%), febrile neutropenia in 5 (31.3%), leukopenia in 2 (12.5%), thrombocytopenia in 1 (6.3%), and heart failure in 1 (6.3%). Grade ≥3 nausea and vomiting did not occur and there was no treatment-related death.
CONCLUSIONS: The oncological outcomes of doxorubicin monotherapy for RPS in real-world clinical practice were not inferior to those of the EORTC trial. The incidence of hematological AEs was higher; however, severe gastrointestinal AEs were prevented by prophylactic antiemetics and there were no treatment-related deaths. Collectively, doxorubicin monotherapy with appropriate prophylactic agents is a valid option for patients with advanced or metastatic RPS.

Retroperitoneal sarcoma (RPS) is a rare disease. RPS invading the abdominal aorta is exceedingly rare and has a poor prognosis. There have been scattered cases of RPS treated with combined abdominal aortic replacement. However, the average survival time for these cases was only 8 months, with a 2-year survival rate of 21%, indicating a poor prognosis. In this case study, a 44-year-old man presented to our hospital complaining of abdominal pain. Multiple imaging findings suggested a retroperitoneal mass that was diagnosed as a malignant tumor. The patient underwent tumor resection with abdominal aortic replacement due to an RPS tumor invading the abdominal aorta. The histopathological grade was determined to be grade 3, the most malignant grade tumor, according to the Fédération Nationale des Centres de Lutte Contre le Cancer grading system. Postoperative chemotherapy with doxorubicin and ifosfamide was administered for five cycles. The patient has been alive for over 8 years after the operation without any recurrence. This case presents a long-term survival of RPS requiring abdominal aortic replacement.

BACKGROUND: Malignant perineurioma is a rare malignant counterpart of perineurioma derived from perineural cells. Resection is the primary option for the treatment of malignant perineuriomas; however, patients often develop recurrence after resection, and effective treatment for advanced or recurrent lesions needs to be established. This report describes a 51-year-old female with a rare malignant perineurioma in the retroperitoneum, which contributing valuable insights to the literature.
METHODS: The patient presented with abdominal distension and the imaging work-up revealed a huge hemorrhagic tumor in the retroperitoneum and obstruction of inferior vena cava by the tumor. The patient underwent surgery retrieving the tumor combined with left hemiliver and retrohepatic vena cava, which confirmed the diagnosis of a malignant perineurioma based on histopathological and immunohistochemical examination. Cancer gene panel testing identified mutations in NF2. Radiotherapy was administered for peritoneal dissemination 2 months after surgery, and the patient died from disease progression 6 months after surgery.
CONCLUSIONS: This rare case highlights the challenges in managing retroperitoneal malignant perineuriomas. The aggressive characteristics and limited treatment options for advanced malignant perineuriomas underscore the need for understanding the pathogenesis and developing effective systemic therapies. The identification of an NF2 mutation provides significant insights into potential therapeutic target.

UNASSIGNED: Low-grade fibromyxoid sarcoma is an uncommon deep-seated soft-tissue sarcoma that occurs rarely in young adults and children. Although surgical resection provides a long-term prognosis, late local recurrence and metastasis may occur.
UNASSIGNED: A 44-year-old woman with no prior medical history presented with breathing and abdominal discomfort. Contrast-enhanced computed tomography scan revealed a retroperitoneal tumor protruding into the thoracic cavity and pleural effusion on the left side. Tumor biopsy revealed sarcoma. We performed complete resection of the tumor along with part of the diaphragm and replaced the diaphragm with a prosthetic patch. Histopathologic findings indicated low-grade fibromyxoid sarcoma. The patient experienced no postoperative complications and received no adjuvant therapy. Furthermore, she survived 4 years after surgery without recurrence.
UNASSIGNED: Complete surgical resection is effective for low-grade fibromyxoid sarcoma; therefore, it is important to plan appropriately for complete resection when biopsy reveals malignant findings.

The development of effective treatment strategies for unresectable retroperitoneal sarcoma is desirable. Herein, we suggest that definitive proton therapy (PT) could be a promising treatment option, regardless of the large size of the tumor. A 52-year-old man presented with a discomfort of the lower abdomen. Computed tomography revealed a retroperitoneal tumor, measuring over 20 cm in the largest dimensions, which was surrounded by the gastrointestinal (GI) tract. Biopsy revealed dedifferentiated liposarcoma. Neoadjuvant chemotherapy was ineffective, and the tumor was ultimately deemed unresectable. The patient opted to receive PT instead of continuation of chemotherapy. Spot scanning PT (SSPT) at a total dose of 60.8 Gy (relative biological effectiveness) in 16 fractions was employed. SSPT administered a dose to the tumor while successfully sparing the surrounding GI tract. He did not receive any maintenance systemic therapy after PT. The tumor gradually shrunk over more than 7 years, with no evidence of recurrence outside the irradiation field. The initial measurable tumor volume of 2925 cc decreased to 214 cc at the final follow-up, seven and a half years after PT. The patient is alive without any severe complications.

UNASSIGNED: Given high risks of major bleeding during retroperitoneal sarcoma(RPS) surgeries, severe complications and deaths are common to see perioperatively. Thus, effective anesthetic management is the key point to ensuring the safety of patients. This study aimed to introduce anesthesia management and mortalities in RPS patients receiving massive blood transfusions during surgeries.
UNASSIGNED: Records of RPS surgeries under general anesthesia from January 2016 through December 2021 were retrospectively retrieved from our database. Patients who received massive blood transfusions (MBT) exceeding 20 units in 24h duration of operations were finally included in this study. Demographics, modalities of anesthesia management, blood loss, transfusion, peri-anesthesia biochemical tests as well as morbidities and mortalities were collected. Risk factors of postoperative 60d mortality were determined through logistic regression in uni-and multi-variety analysis using the statistics software STATA 17.0.
UNASSIGNED: A total of 70 patients (male 31) were included. The mean age was 50.1 ± 15.8 years. All patients received combined resections of sarcoma with involved organs under general anesthesia. Mean operation time and anesthesia time were 491.7 ± 131.1mins and 553.9 ± 132.6mins, respectively. The median intraoperative blood loss was 7000ml (IQR 5500,10000ml). Median red blood cells (RBC) and fresh frozen plasma (FFP) transfusion were 25.3u (IQR 20,28u), and 2400ml (IQR 2000,3000ml), respectively. Other blood products infusions included prothrombin complex concentrate (PCCs), fibrinogen concentrate (FC), platelet(plt) and albumin(alb) in 82.9% (58/70), 88.6% (62/70), 81.4% (57/70) and 12.9% (9/70) of patients. The postoperative severe complication rate(Clavien-Dindo grade≥3a) was 35.7%(25/70). A total of 7 patients (10%) died during the postoperative 60-day period. BMI, volumes of crystalloid infusion in anesthesia, and hemoglobin and lactate levels at the termination of operation were found significantly associated with postoperative occurrence of death in univariate analysis. In logistic multivariate analysis, extended anesthesia duration was found associated with postoperative venous thrombosis embolism (VTE) and severe complication. The lactate level at the immediate termination of the operation was the only risk factor related to perioperative death (p<0.05).
UNASSIGNED: RPS patients who endure MBT in surgeries face higher risks of death postoperatively, which needs precise and effective anesthesia management in high-volume RPS centers. Increased blood lactate levels might be predictors of postoperative deaths which should be noted.

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).
CONCLUSIONS: 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.

BACKGROUND: Retroperitoneal sarcomas (RPS) are rare tumours of mesenchymal origin, commonly presented as a large tumour mass at time of diagnosis. We investigated the impact of body composition on outcome in patients operated on for primary localized RPS.
METHODS: We retrospectively analysed data for all patients operated on for primary RPS at our institution between 1999 and 2020. Preoperative skeletal muscle area (SMA), visceral and subcutaneous adipose tissue area (VAT and SAT) and muscle radiation attenuation (MRA) were calculated using computed tomography scans at the level of third lumbar vertebra. European Working Group on Sarcopenia in Older People (EWGSOP2) criteria were applied to define myopenia. Using maximum log-rank statistic method we determined the optimal cut-off values of body composition parameters. Myosteatosis was defined based on determined MRA cut-offs.
RESULTS: In total 58 patient were eligible for the study. With a median follow-up of 116 months, the estimated 5-year overall survival (OS) and local-recurrence free survival (LRFS) were 66.8% and 77.6%, respectively. Patients with myopenia had significantly lower 5-year OS compared to non-myopenic (p = 0.009). Skeletal muscle index and subcutaneous adipose tissue index predicted LRFS on univariate analysis (p = 0.052 and p = 0.039, respectively). In multivariate analysis high visceral-to-subcutaneous adipose tissue area ratio (VSR) independently predicted higher postoperative complication rate (89.2% vs. 10.8%, p = 0.008). Myosteatosis was associated with higher postoperative morbidity.
CONCLUSIONS: Myopenia affected survival, but not postoperative outcome in RPS. Visceral obesity, VSR (> 0.26) and myosteatosis were associated with higher postoperative morbidity. VSR was better prognostic factor than VAT in RPS.

Retroperitoneal sarcoma (RPS) is a rare tumor classified into many histological types. It is also often detected only after it has grown to a considerable size and requires extensive resection of the surrounding organs, making it difficult to offer optimal patient-tailored management. Evidence supporting specific treatment modalities for RPS is insufficient, owing to its rarity. The Japanese clinical practice guidelines for RPS were published in December 2021, with the aim of accumulating existing evidence and indicating the optimal practice for RPS. These guidelines provide important clinical questions (CQs) concerning the diagnosis and treatment of RPS. This review, with a particular focus on primary RPS, attempts to introduce clinical problems in the diagnosis and treatment of RPS and to assess those problems along with the CQs in the guidelines. According to these guidelines, although chemotherapy and radiotherapy are expected to have therapeutic effects, the level of evidence to support these treatments is not very high at present. Accordingly, complete resection of the tumor is the first and only option for managing primary RPS. However, as with other tumors, the demand for multidisciplinary treatment for RPS is increasing. These guidelines will undoubtedly represent a milestone in clinical practice in relation to RPS in the future, and further evidence is expected to be accumulated based on the CQs that have been proposed.