Retroperitoneal Soft Tissue Sarcoma Research Articles

Analysis of the Onco-Vascular Approach in Retroperitoneal Sarcoma with Vascular Involvement

Background: Due to the limited number of clinical series and the lack of multi-institutional or national registries concerning retroperitoneal sarcoma (RPS) extending to major arterio-venous structures, the short and long-term benefits following concomitant resection of these major structures are still antagonistic. Objective: To present our institutional experience with RPS tumors, to assess their vascular involvement and to analyze the outcomes of onco-vascular approach. Patients and methods: A retrospective review of our institutional RPS patients’ clinical charts was performed. All consecutive adult patients surgically treated for RPS were included. Resection of RPS tumors was followed by histopathological examination for grading. Types of vascular involvement were assessed preoperatively. RPS tumors were resected en bloc together with blood vessels according to the type of vascular involvement and the surgical standards. Results: This study included 14 patients; 8 males (57%) and 6 females (43%) with RPS. Vascular resection was performed in all patients. Adherent structures were resected in 43%. Resection was performed for 29% RPSs with arterial venous involvement, 14% with only arterial involvement, and 57% with only venous involvement. All RPSs were classified as high-grade lesions, and 64% showed secondarily major vessels involvement. 43% of patients were treated by arterial resection. 80% had venous involvement. Venous resections were followed by venous reconstruction in all patients with both arterial and venous involvement. The morbidity rate was 43% while the mortality rate was 7%. Conclusion: Complete resection with clear margins is important for long-term survival in patients with retroperitoneal soft tissue sarcomas.

Posterior Reversible Encephalopathy Syndrome Induced by Pazopanib in a Patient with Soft-Tissue Sarcoma: A Case Report

Posterior reversible encephalopathy syndrome (PRES), a rare disease is characterized by multiple neurological complications. It has been reported to be associated with the use of angiogenesis inhibitors such as sorafenib, sunitinib, pazopanib, regorafenib, and lenvatinib. We reported a case of 76-year-old woman with history of stage III hepatocellular carcinoma (HCC), who developed adverse drug reactions related to pazopanib induced PRES. Pazopanib, an angiogenesis inhibitor which inhibits the vascular endothelial growth factor (VEGF) pathway may lead to vascular endothelial damage, and these pathophysiological changes may lead to vascular leaks and brain edema. Medical staff must be aware of the possible association between angiogenesis inhibitors and the development of PRES. In patients with retroperitoneal soft-tissue sarcoma undergoing treatment with pazopanib, regular monitoring of their blood pressure and following-up brain magnetic resonance imaging (MRI) should be encouraged.

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

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. 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. 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. 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.

Management of locoregional recurrence after radical resection of a primary nonmetastatic retroperitoneal soft tissue sarcoma: The Gustave Roussy experience.

Despite surgery, many patients experience locoregional recurrence (LR), the optimum treatment of which is still debated. All 297 consecutive patients operated for a nonmetastatic primary retroperitoneal soft tissue sarcoma (RPS) between 1994 and 2017 were retrospectively analyzed to report our experience in treating LR. After a median follow-up of 97 months, 55 patients (19%) developed LR. The first site of recurrence was locoregional in 100% with associated peritoneal metastases in 45% and distant metastases in 5%. After LR treatment, the 1-, 3-, and 5-year overall survival (OS) rates were 71%, 46%, and 33%. Low tumor grade, disease-free interval above 24 months, exclusive LR, and well-differentiated liposarcoma were predictive of better OS. The treatment strategy (best supportive care, chemotherapy radiotherapy, and/or surgery) was not statistically significant. Fourteen patients underwent initial surveillance (strategic delay) for low-grade LR and eventually required treatment in 86% after a median delay of 20 months during which no patient developed distant metastases. The management of LR in RPS is complex. An initial surveillance may not alter survival in asymptomatic low-grade and slow-growing LR. An LR decision scheme is proposed.

Challenging New AJCC 8 Staging For Soft Tissue Sarcoma Using The NCDB

Soft tissue sarcoma (STS) is a rare and heterogeneous entity for which there are many challenges to staging. One of the most significant updates in the AJCC 8th edition is the grouping of N1 and M1 collectively into stage IV disease. The aim of this study is to present an analysis of the impact of N1 vs. M1 disease on the overall survival (OS) of STS patients treated in the modern era and in the context of the contemporary AJCC staging system. Adult STS patients were identified in the 2004 – 2014 NCDB, classified by the WHO 2013 system into 10 major histologic subtypes and grouped according to new AJCC 8 staging. Primary retroperitoneal STS, patients with “other/unusual” histologic subtypes and those who had delays in therapy (>180 days from diagnosis) were excluded. Chi-square tests were used to compare demographic factors, tumor characteristics, and therapy received, while Kaplan-Meier estimates, Cox proportion hazard ratios and log rank tests were used for survival analyses. Of the 82,987 adult STS patients identified, 55,417 met inclusion criteria. On univariable analysis, females, patients >50yo and those with low grade tumors were less likely to be N1 (p< 0.01). No significant difference was found in the likelihood of having N1 disease between tumor sizes </=5cm and those >5cm. Multivariable analysis identified N1 and M1 disease as independent factors associated with overall survival (HR= 1.34, p< 0.001 and HR= 2.52, p< 0.0001, respectively). N1 patients were more likely to have M1 disease (OR= 2.5) compared to N0 patients (p< 0.001). M1 disease was more likely in African Americans than in Whites, in intermediate/high grade than in low grade tumors and in tumors >5cm than in those </=5cm (p< 0.001). There were significant differences in 10-year OS between AJCC 8 stage groups 1-4 (63.3%, 48.7%, 32.3% and 7.9%, respectively); p< 0.001. N1 patients were found to have a significantly shorter 5-year OS (34.4%) and 10-year OS (27.3%) compared with N0 patients (65.3% and 49.9%, respectively); p< 0.001. There were no significant differences in the 5- and 10-year OS of N0M1 patients (10% and 5.4%, respectively) compared with N1M1 patients (11.31% and 0%, respectively); p= 0.95. As such, further analyses combined N1M1 and N0M1 into one M1 group. There was a significant difference in 5- and 10-year OS of N1M0 patients (34.4% and 27.3%, respectively) relative to (N1/0)M1 patients (10% and 5.4%, respectively); p<0.0001. Using the NCDB, we demonstrate a significant separation in OS between N1M0 and M1 adult patients with STS. We confirm that N0 patients fare much better than their N1 counterparts in OS. The data also demonstrate that N1 patients have significantly improved 10-year OS (27.3%) compared to that of M1 patients (5.4%). These results suggest that the new AJCC 8th edition grouping of N1 and M1 patients into stage IV may obscure the more favorable prognosis of patients with N1M0 disease.

Surgical resection for recurrent retroperitoneal leiomyosarcoma and liposarcoma

BackgroundRetroperitoneal soft tissue sarcomas (STS) include a number of histologies but are rare, with approximately 3000 cases in the USA per year. Retroperitoneal STS have a high incidence of local and distant recurrence. The purpose of this study was to review the University of Maryland Medical Center’s (UMMC) treatment experience of retroperitoneal STS, where the patient population served represents a diverse socioeconomic and ethnic catchment.MethodsIRB approval was obtained. We constructed a de-identified database of patients diagnosed with retroperitoneal liposarcomas (LPS) or leiomyosarcomas (LMS) treated at UMMC between 2000 and 2013. A total of 49 patients (Pts) with retroperitoneal STS met our eligibility criteria. Kaplan-Meier plots were used to graphically portray progression-free survival (PFS) and overall survival (OS). The log-rank test was used to compare time-to-event distributions.ResultsThe median OS for all patients (Pts) was 6.3 years, and the 2-year OS rate was 81%. The median PFS for all Pts was 1.8 years, and the 2-year PFS rate was 45%. There was no difference in OS and PFS among LMS and LPS patients; the median OS for LMS was 3.8 years vs. LPS 6.4 years (p = 0.33), and the median PFS for LMS was 1.2 years vs. LPS 2.5 years (p = 0.28). There was a significant difference between histology and race (p = 0.001). LPS were primarily Caucasian 86% vs. 14% black, whereas LMS were primarily black 52% vs. 33% Caucasian. OS was influenced by functional status, gender, American Joint Committee on Cancer (AJCC) stage, grade, histology, tumor size, and extent of resection. PFS was influenced by AJCC stage, grade, and extent of resection. Neither adjuvant chemotherapy (1 Pt) nor neoadjuvant/adjuvant radiation therapy (18 Pts) influenced OS or PFS. There was a non-significant difference that Pts who could undergo resection of local recurrence had improved 2-year OS, with 100% LMS and LPS compared to 2-year OS of 71% (LMS) and 78% (LPS) not undergoing resection of local recurrence.ConclusionsThis study suggests a higher incidence of leiomyosarcoma in the African-American population. This study confirms the prognostic importance of grade, tumor size, AJCC stage, histology, and extent of resection in patient outcomes, at a large substantially diverse academic medical center. Future research into the biological features of liposarcoma and leiomyosarcoma Pts imparting these characteristics will be important to define.

1653P - Management of locoregional recurrence after radical resection of a primary non-metastatic retroperitoneal soft tissue sarcoma: Results of a retrospective series in a tertiary care center

1653P - Management of locoregional recurrence after radical resection of a primary non-metastatic retroperitoneal soft tissue sarcoma: Results of a retrospective series in a tertiary care center

Hospital Factors and Sources of Variation in Mortality After Treatment of Retroperitoneal Soft-Tissue Sarcoma: Results Beyond TNM Staging

Villano, Anthony M. MD; Zeymo, Alexander MS; Chan, Kitty S. PhD; Shara, Nawar PhD; Unger, Keith MD; AlRefaie, Waddah B. MBBCh, FACS Author Information

Staging, nomograms and other predictive tools in retroperitoneal soft tissue sarcoma.

Patient outcomes following surgical resection of retroperitoneal sarcomas (RPSs) are variable and therefore predicting prognosis is challenging. The risk of recurrence varies according to several patient- tumour- and treatment-related characteristics, including histological subtype and tumour grade. In an era of increased movement towards individualised patient care, the ability to predict prognosis following surgery for RPS is essential. The accurate prediction of an individual patient's outcome is important to allow adequate patient counselling and to ensure the optimal therapeutic strategy is selected. The outcomes of patients who have undergone resection for RPS can be predicted using tools such as nomograms. Nomograms take into account the relative contribution of each variable by giving them different weights and then combining them. This review aims to discuss current staging systems available for RPS and to critically appraise predictive tools that are currently available for use in clinical practice.

The influence of anatomic location on outcomes in patients with localized primary soft tissue sarcoma.

We hypothesized that survival varied significantly between retroperitoneal soft tissue sarcoma (STS) and extremity/trunk STS. This study explored the reasons for the different outcomes and identified patient characteristics for survival. This retrospective study identified 213 consecutive patients with localized primary STS from January 2002 to July 2013, including 47 retroperitoneal STS (22.1%) and 166 extremity/trunk STS (77.9%). Local failure-free survival (LFFS), distant metastasis-free survival (DMFS) and overall survival (OS) were constructed by the Kaplan-Meier method. Univariate Cox proportional hazards regression models were fit to assess the ability of patient characteristics to predict survival. At presentation, patients with retroperitoneal STS had larger tumor size (median size 18 cm vs. 6 cm; P < 0.001) and positive margin (21.3% vs. 8.4%; P = 0.014), and less often received radiotherapy (2.1% vs. 45.8%; P < 0.001). The median follow-up time for the entire population was 68 months (range, 5-127 months). Local recurrence was more frequent in patients with retroperitoneal STS compared with patients with extremity/trunk STS (53.2% vs. 28.3%; P = 0.001). LFFS and OS were lower in patients with retroperitoneal STS than extremity/trunk STS, with 5-year LFFS (50% vs. 74.3%; P < 0.001) and 5-year OS (65.4% vs. 77.5%; P = 0.017), respectively. Retroperitoneal STS was associated with significantly worse survival compared with extremity/trunk STS. Larger tumor size, more patients with positive margin and fewer patients received radiotherapy in retroperitoneal group may result in worse survival compared with extremity/trunk disease.

The Volume-Outcome Relationship in Retroperitoneal Soft Tissue Sarcoma: Evidence of Improved Short- and Long-Term Outcomes at High-Volume Institutions.

Background We sought to study the association between RPS case volume and outcomes. Although a relationship has been demonstrated between case volume and patient outcomes in some cancers, such a relationship has not been established for retroperitoneal sarcomas (RPSs). Study Design The National Cancer Database (NCDB) was queried for patients undergoing treatment for primary RPS diagnosed between 2004 and 2013. Mean annual patient volume for RPS resection was calculated for all hospitals and divided into low volume (<5 cases/year), medium volume (5–10 cases/year), and high volume (>10 cases/year). Risk-adjusted regression analyses were performed to identify predictors of 30-day surgical mortality, R0 margin status, and overall survival (OS). Results Our study population consisted of 5,407 patients with a median age of 61 years, of whom 47% were male and 3,803 (70%) underwent surgical resection. Absolute 30-day surgical mortality and R0 margin rate following surgery for low-, medium-, and high-volume institutions were 2.4%, 1.3%, and 0.5% (p=0.027) and 68%, 65%, and 82%, (p < 0.001), respectively. Five-year overall survival rates for low, medium, and high-volume institutions were 56%, 57%, and 66%, respectively (p < 0.001). Patients treated at low-volume institutions had a significantly higher risk of 30-day mortality (adjusted OR = 4.66, 95% CI 2.26–9.63) and long-term mortality (adjusted HR = 1.56, 95% CI 1.16–2.11) compared to high-volume institutions. Conclusion We demonstrate the existence of a hospital sarcoma service line volume-oncologic outcome relationship for RPS at the national level and provide benchmark data for cancer care delivery systems and policy makers.

Current therapy of retroperitoneal sarcomas

The location of soft tissue sarcoma (STS) in the retroperitoneal space (about 15% of all STS) is a special therapeutic challenge, which is why these cancers should be strictly treated in specialised centres. The most common subtypes in this area are liposarcoma (mainly well-differentiated liposarcoma WD LPS and dedifferentiated liposarcoma DD LPS), leiomyosarcoma, and solitary fibrous tumour. The specificity of retroperitoneal sarcomas (RPS) is based on a high potential for local recurrence, less frequent occurrence of lung metastases (more often to the liver), and greater difficulty in achieving adequate tissue margins (extra compartmental locations, invasion of vital organs). The main prognostic factors include the size of the tumour, histological subtype, histological malignancy, multifocality, and radicalism of the resection. Nomograms can be used to assess the prognosis. Extensive resections that include the adjacent organs (kidney, intestine, muscles, liver) along with the tumour are the only way to cure these cancers and are particularly justified in cases where no macroscopic tumour fragments are left. When planning the treatment preoperative radiotherapy should be considered and also (in high-grade cases) chemotherapy based on doxorubicin and ifosfamide. During the surgery together with the tumour are often removed: kidneys/adrenal glands (in about 50% of patients), large intestine — right or left-sided hemicolectomy (over 20%), part of the pancreas (15%), and spleen (10%). Block resections of retroperitoneal STS together with infiltrated peripheral organs improves patients’ survival (especially in the case of liposarcoma). Some authors propose operating RPS in a “compartmental” manner, removing also the unoccupied surrounding organs, such as the spleen, pancreatic tail, kidney, and lumbar muscle, which may improve the patient outcome because microscopic infiltration of adjacent organs, which macroscopically are not occupied by sarcoma in over 60%. A liberal approach to resection of adjacent organs that are not involved by cancer should always be considered when the scope of surgical treatment is selected. The quality of the margins should be taken into account, as well as the histological type and the expected complications. Surgical complications after extensive MPZ operations concern about 12–15% of patients. Determination of infiltration of the inferior vena cava in the imaging tests requires special analysis because some of the operated cases of leiomyosarcoma may develop from its wall.

Use of 18F-FDG-PET/CT for Retroperitoneal/Intra-Abdominal Soft Tissue Sarcomas.

Rationale To assess the diagnostic value of 18F-FDG-PET/CT for different retroperitoneal soft tissue sarcomas (STS) and other similar tumors. To analyze the predictive value of 18F-FDG-PET/CT for histological grade and main prognostic factors. Methods 195 patients with 44 different diseases have been included. Relationship between SUVmax, Clinical, pathological, and prognostic information has been analyzed. Results Malignant tumors do not show higher SUVmax than benign ones (P=0.443). We divided all 44 different diseases into two groups; SUVmax of group 1 is significantly higher than group 2 (P ≤ 0.001). The ROC curve suggests 4.35 is the cutoff value to distinguish groups 1 and 2 (sensitivity = 0.789; specificity = 0.736). SUVmax correlates with Ki-67 index, mitotic count, vascular resection, histological grade, and recurrent STS without considering pathological diagnosis (P=0.001, P=0.012, P=0.002, P ≤ 0.001, and P=0.037, resp.). Conclusion 18F-FDG-PET/CT cannot simply distinguish malignant and benign tumors in retroperitoneal/intra-abdominal cavity; however, the SUVmax of malignant tumors, inflammatory pseudotumor, and PPGL group is higher than the SUVmax of benign tumors, lymph node metastasis, hematoma, and low malignant STS group. Guidance of “SUVmax location” may be helpful for biopsy and pathology dissection.

Pathologic Staging of Bone and Soft Tissue Tumors: What Is New in the Eighth Edition of the American Joint Committee on Cancer Staging Manual?

Abstract The recently published eighth edition of the AJCC Cancer Staging Manual addresses and incorporates a substantial number of advances in our understanding of bone and soft tissue sarcomas. A greater emphasis has been placed on the anatomic site of origin resulting in new staging systems. In addition, modifications to the existing AJCC prognostic stage groups and implementation of new prognostic stage groups for certain anatomic sites and tumor types were made. Minor changes in the biologic grading of bone sarcomas were also included. For retroperitoneal soft tissue sarcomas, a nomogram providing additional prognostic information has been endorsed by the AJCC Precision Medicine Core and is included as a risk assessment model. Pathologists play a central role in tumor staging and therefore should become familiar with these changes.

An Update in the Management of Retroperitoneal Soft Tissue Sarcoma

An Update in the Management of Retroperitoneal Soft Tissue Sarcoma

A rare case of retroperitoneal synovial sarcoma

LessonManagement of retroperitoneal soft tissue sarcomas is complex. Treatment is usually multimodal; involving surgery, chemotherapy and radiotherapy.

The Benefit of Adjuvant Radiotherapy in High-grade Nonmetastatic Retroperitoneal Soft Tissue Sarcoma: A SEER Analysis.

Controversy persists on the use of adjuvant radiotherapy (RT) in patients with retroperitoneal sarcoma (RPS). High-grade disease is known to be associated with decreased local control and overall survival (OS). Because RT has proven beneficial for local control and OS in patients with high-grade extremity soft tissue sarcoma, we evaluated the efficacy of adjuvant RT in high-grade RPS. The Surveillance, Epidemiology, and End Results database was used to identify patients with pathology-confirmed RPS from 1973 to 2010. Clinical characteristics and outcomes were analyzed. Of 480 total patients, 144 (30.0%) received postoperative radiation. Patients who received adjuvant RT had improved median OS (36 mo) compared with those who did not (27 mo, hazard ratio [HR]=0.79, P=0.023). On multivariate analysis the use of adjuvant RT (HR=0.80; 95% confidence interval [CI], 0.65-0.98; P=0.029), male sex (HR=1.32; 95% CI, 1.10-1.59; P=0.003), age above 65 years (HR=1.38; 95% CI, 1.15-1.67; P=0.001), and increasing the Surveillance, Epidemiology, and End Results historical stage (HR=1.46; 95% CI, 1.21-1.76; P<0.001) were all prognostic factors for OS. In a large retrospective analysis, postoperative RT improved OS in high-grade RPS patients. As such, adjuvant RT should be strongly considered in all patients with high-grade RPS. The optimal timing of RT relative to surgery requires further study.

Aggressive Surgical Approach for Treatment of Primary and Recurrent Retroperitoneal Soft Tissue Sarcoma

To analyze treatment and survival in a series of resected patients with primary or recurrent retroperitoneal sarcoma (RPS) treated and prospectively followed at a single institution. Between July 1994 and December 2015, 89 patients (36 M, 53 F; mean age 60years, range 25-79) were evaluated. For the purpose of analysis, complete resection was defined as removal of gross tumor with histologically confirmed clear resection margins. Eighty-three out of the 89 patients (93%), 46 of whom affected by primary RPS, and 37 by recurrent RPS, underwent surgical exploration. Sixty-two had a grossly and microscopically complete resection. Fifty-three out of 83 patients (64%) underwent removal of contiguous intra-abdominal organs. Preoperative mortality was nil and significant preoperative complications occurred in six cases only (7%). High-grade tumor pointed out to be a significant variable for a worse survival in all 83 patients amenable to undergo surgical resection (57% 5years survival for low grade vs 14% for high grade; P = 0.0004). Among completely resected patients, only histologic grade clearly affected disease-free survival (72% 5years survival for low grade vs 50% for high grade; P = 0.04), while the role of preoperative blood transfusions (67% 5years survival for non-transfused patients vs 29% for transfused patients; P = 0.05) has to be evaluated in connection to patient complexity. Histological grade and recurrence are the most valuable prognostic predictors; in this clinical subset, an aggressive surgical approach in both primary and recurrent RPS is associated with a best long-term survival and disease-free survival.

Efficacy of Postoperative Radiotherapy Using Modern Techniques in Patients with Retroperitoneal Soft Tissue Sarcoma.

PurposeLocal recurrence is the most common cause of failure in retroperitoneal soft tissue sarcoma patients after surgical resection. Postoperative radiotherapy (PORT) is infrequently used due to its high complication risk. We investigated the efficacy of PORT using modern techniques in patients with retroperitoneal soft tissue sarcoma.Materials and MethodsEighty patients, who underwent surgical resection for non-metastatic primary retroperitoneal soft tissue sarcoma at the Yonsei Cancer Center between 1994 and 2015, were retrospectively reviewed. Thirty-eight (47.5%) patients received PORT: three-dimensional conformal radiotherapy in 29 and intensity-modulated radiotherapy in nine patients. Local failure-free survival (LFFS), overall survival (OS), and RT-related toxicities were investigated.ResultsMedian follow-up was 37.1 months (range, 5.8–207.9). Treatment failure occurred in 47 (58.8%) patients including local recurrence in 33 (41.3%), distant metastasis in eight (10%), and both occurred in six (7.5%) patients. The 2-year and 5-year LFFS rates were 63.9% and 47.9%, respectively. The 2-year and 5-year OS rates were 87.5% and 71.1%. The 5-year LFFS rate was significantly higher in PORT group than in no-PORT group (74.2% vs. 24.3%, p<0.001). In multivariate analysis, PORT was the only independent prognostic factor for LFFS. However, there was no significant correlation between RT dose and LFFS. OS showed no significant difference between the two groups. Grade ≤2 acute toxicities were observed in 63% of patients, but no acute toxicity ≥grade 3 was observed.ConclusionPORT using modern technique markedly reduced local recurrence in retroperitoneal sarcoma patients, with low toxicity. The optimal RT technique, in terms of RT dose and target volume, should be further investigated.

Post-operative surveillance in retroperitoneal soft tissue sarcoma: The importance of tumor histology in guiding strategy.

Crafting effective surveillance strategies for retroperitoneal soft tissue sarcomas is difficult given the scarcity of literature on this rare disease. In this article, we will summarize the most recent literature on natural history and recurrence patterns of RPS compiled from multi-institutional collaborative studies and centers with extended follow-up data, and based on this evidence, propose principles for histology-based post-operative surveillance protocols.