Pathology of retroperitoneal sarcomas: A brief review

Response to Central Boost Radiation Therapy in Unresectable Retroperitoneal Sarcoma: A Case Series

Purpose

Optimal treatment of retroperitoneal sarcoma (RPS) remains undefined. Here, we report the feasibility of using high-dose boost radiation (3-4 Gy) to the central part of the tumor in patients with unresectable RPS.

Methods and Materials

Five patients with unresectable RPS were treated with radiation therapy using a central boost technique with intensity modulated radiation therapy. On average, doses of 25 Gy to 45 Gy were delivered to the outer part of the tumor (planning target volume 1), while the central part of the tumor (planning target volume 2) received a 56 Gy to 75 Gy physical dose, which translates to a 62.67 Gy to 87.5 Gy equivalent dose in 2 Gy fractions (EQD2). To minimize radiation toxicity to the adjacent bowel and other organs, we used sequential, interdigitated, or simultaneous integrated boost (SIB) techniques.

Results

In this case series of variable RPS histology, the median survival postradiation therapy was 30 months. Three of the 5 patients had clinically stable local disease on follow-up scans, and none of the patients experienced clinically significant toxicity.

Conclusions

In summary, in this small case series of 5 patients, treatment was tolerated well, and excellent local responses were observed regardless of the timing of the central boost. Given the high rates of metastatic disease that developed in responding patients, effective systemic therapy will likely be needed for unresectable RPS treated with aggressive radiation therapy to the central part of the tumor.

Lifelong Imaging Surveillance is Indicated for Patients with Primary Retroperitoneal Liposarcoma

BACKGROUND

Surveillance imaging of patients with retroperitoneal liposarcoma (RP-LPS) after surgical resection is based on a projected risk of locoregional and distant recurrence. The duration of surveillance is not well defined because the natural history of RP-LPS after treatment is poorly understood. This study evaluated the long-term risk of recurrence and disease-specific survival (DSS) for a cohort of patients with at least 10 years of progression-free survival (10yr-PFS) from their primary resection.

METHODS

The prospective University of California, Los Angeles (UCLA) Sarcoma Database identified RP-LPS patients with 10yr-PFS after initial resection. The patients in the 10yr-PFS cohort were subsequently evaluated for recurrence and DSS. The time intervals start at date of initial surgical resection. Cox proportional hazards models were used to determine factors associated with recurrence and DSS.

RESULTS

From 1972 to 2010, 76 patients with RP-LPS had at least 10 years of follow-up evaluation. Of these 76 patients, 39 (51%) demonstrated 10yr-PFS. The median follow-up period was 15 years (range 10-33 years). Among the 10yr-PFS patients, 49% (19/39) experienced a recurrence at least 10 years after surgery. Of those who experienced recurrence, 42% (8/19) died of disease. Neither long-term recurrence nor DSS were significantly associated with age, sex, tumor size, LPS subtype, surgical margin, or perioperative treatment with radiation or chemotherapy.

CONCLUSION

Patients who have primary RP-LPS treated with surgical resection ± multimodality therapy face a long-term risk of recurrence and disease-specific death unacknowledged by current surveillance imaging guidelines. Among the patients with 10yr-PFS, 49% experienced a recurrence, and 42% of those died of disease. These findings suggest a need for lifelong surveillance imaging for patients with RP-LPS.

Updates in Pathology for Retroperitoneal Soft Tissue Sarcoma

Retroperitoneal tumors are extremely rare. More than 70% of primary retroperitoneal soft tissue tumors are malignant. The most common sarcomas in the retroperitoneum include liposarcomas and leiomyosarcoma, however other sarcomas, along with benign mesenchymal tumors, can occur. Sarcomas are a heterogenous group of tumors with overlapping microscopic features, posing a diagnostic challenge for the pathologist. Correct tumor classification has become important for prognostication and the evolving targeted therapies for sarcoma subtypes. In this review, the pathology of retroperitoneal soft tissue sarcomas is discussed, which is important to the surgical oncologist. In addition, less common sarcomas and benign mesenchymal tumors of the retroperitoneum, which may mimic sarcoma clinically and pathologically, are also discussed.

Surgical Principles of Primary Retroperitoneal Sarcoma in the Era of Personalized Treatment: A Review of the Frontline Extended Surgery

Simple Summary

Surgery is the only curative treatment for localized disease in retroperitoneal sarcoma (RPS). Frontline extended surgery, or compartmental surgery, is a recent surgical strategy consisting of resecting the tumor together with adjacent organs, with the aim of minimizing marginality. This review provides a practical step by step description of this standardized procedure, tailored to histologic behavior, tumor localization, and patient condition.

Abstract

Surgery is the key treatment in retroperitoneal sarcoma (RPS), as completeness of resection is the most important prognostic factor related to treatment. Compartmental surgery/frontline extended approach is based on soft-tissue sarcoma surgical principles, and involves resecting adjacent viscera to achieve a wide negative margin. This extended approach is associated with improved local control and survival. This surgery must be tailored to tumor histology, tumor localization, and patient performance status. We herein present a review of compartmental surgery principles, covering the oncological and technical basis, and describing the tailored approach to each tumor subtype and localization in the retroperitoneum.

Role of Radiation Therapy for Newly Diagnosed Retroperitoneal Sarcoma

OPINION STATEMENT

Soft tissue sarcomas (STS) are rare, aggressive, and heterogenous tumors, comprising approximately 1% of adult cancers with over 50 different subtypes. The mainstay of treatment for retroperitoneal sarcomas (RPS) includes surgical resection. The addition of radiation therapy (RT), either preoperatively or postoperatively, has been used to potentially decrease the risk of local recurrence. The recently published results from STRASS (EORTC-STBSG 62092-22092), which randomized patients to receive or not receive preoperative radiation, indicate no abdominal recurrence-free survival benefit (primary endpoint) nor overall survival benefit to date from the addition of preoperative RT prior to surgical resection in patients with RPS. Keeping in mind caveats of subgroup analyses, the data show a significant reduction in local recurrence with radiation therapy in resected patients and non-significant trends toward improved abdominal recurrence-free survival in all patients and improved local control and abdominal recurrence-free survival in patients with liposarcoma and low-grade sarcoma. Given the high rate of local failure with surgery alone, it is possible that higher RT dose and/or selective RT dose painting may improve outcomes. Prior to treatment, the authors encourage multidisciplinary review and discussion of management options at a sarcoma center for patients with RPS. Selective use of RT may be considered for patients at high risk of local recurrence.

[French ccAFU guidelines - update 2020-2022: retroperitoneal sarcoma]

OBJECTIVE

- To update French urological guidelines on retroperitoneal sarcoma.

MATERIALS AND METHODS

- Comprehensive Medline search between 2018 and 2020 upon diagnosis, treatment and follow-up of retroperitoneal sarcoma. Level of evidence was evaluated.

RESULTS

- Chest, abdomen and pelvis CT is mandatory to evaluate any suspected retroperitoneal sarcoma. MRI sometimes helps surgical planning. Before histological confirmation through biopsy, the patient must be registered in the French sarcoma pathology reference network. The biopsy standard should be an extraperitoneal coaxial percutaneous sampling before any retroperitoneal mass therapeutic decision. Surgery is retroperitoneal sarcoma cornerstone. The main objective is grossly negative margins and can be technically challenging. Multimodal treatment risks and benefits must be discussed in multidisciplinary teams. The relapse rate is related to tumor grade and surgical margins. Reported Negative margins rate thus encourage surgery in high-volume centers.

CONCLUSION

- Retroperitoneal sarcoma prognosis is poor and closely related to the quality of initial management. Centralization through dedicated sarcoma pathology network in a high-volume center is mandatory.

Poorly-differentiated and undifferentiated sarcomas of the mediastinum: a bag of tricks

Mediastinum is a Pandora's Box containing many different structures that can give origin to several cancer types. Our aims are to provide a general framework to make a diagnosis of an undifferentiated pleomorphic sarcoma and to highlight relevant immunohistochemical and molecular techniques that can help in the differential diagnosis. We, therefore, provide a simple three-step algorithmic approach to diagnose pleomorphic sarcoma, emphasizing the role of clinicopathological correlations and advocating for a "relative frequency" method, especially when the material for the diagnosis is scarce, as in small biopsies. In the first place, if clinical and/or radiological features make a non-sarcoma diagnosis more likely, it should be ruled in. Next, even if no specific non-sarcomatous diagnoses are suspected, they should always be ruled out. Lastly, since many sarcomas can have a pleomorphic appearance, specific entities should also be ruled out because their identification might affect prognosis and treatment. We then cover selected immunohistochemical and molecular ancillary tests that can come at hand in the diagnosis, highlighting the pros and cons; in particular the use and the limitations of H3K27me3 immunohistochemistry, the meaning of MDM2 amplification in the mediastinum and the implication of muscle differentiation-either smooth or skeletal-in sarcomas. The main take home messages are to always rule-out more frequent lesion first and always include clinical and radiological information in the diagnostic process.

Soft Tissue Tumors of the Abdomen and Retroperitoneum

Soft tissue tumors of the abdomen and retroperitoneum encompass a wide range of benign and malignant neoplasms. Retroperitoneal sarcomas, the most common, are composed of rare malignancies with numerous histiotypes. Surgery remains the cornerstone of treatment and the only curative option for retroperitoneal sarcomas. With histiotype-dependent local and distant recurrences, it is imperative these cases are discussed in a multidisciplinary tumor board setting at specialized sarcoma centers. This review discusses the current evidence for the management of abdominal and retroperitoneal soft tissue tumors, with particular focus on retroperitoneal sarcomas and desmoid tumors.

[French ccAFU guidelines - Update 2018-2020: Retroperitoneal sarcoma]

OBJECTIVE

To update French urological guidelines on retroperitoneal sarcoma.

METHODS

Comprehensive Medline search between 2016 and 2018 upon diagnosis, treatment and follow-up of retroperitoneal sarcoma. Level of evidence was evaluated.

RESULTS

Chest, abdomen and pelvis CT is mandatory to evaluate any suspected retroperitoneal sarcoma. MRI sometimes helps surgical planning. Before histological confirmation through biopsy, the patient must be registered in the French sarcoma pathology reference network. The biopsy standard should be an extraperitoneal coaxial percutaneous sampling before any retroperitoneal mass therapeutic decision. Surgery is retroperitoneal sarcoma cornerstone. The main objective is grossly negative margins and can be technically challenging. Multimodal treatment risks and benefits must be discussed in multidisciplinary teams. The relapse rate is related to tumor grade and surgical margins.

CONCLUSION

Retroperitoneal sarcoma prognosis is poor and closely related to the quality of initial management. Centralization through dedicated sarcoma pathology network in a high-volume center is mandatory.

CT-morphologic and CT-textural patterns of response in inoperable soft tissue sarcomas treated with pazopanib-a preliminary retrospective cohort study

OBJECTIVE

To analyze patterns of response in soft tissue sarcomas exposed to pazopanib using CT-morphologic and textural features and their suitability for evaluating therapeutic response.

METHODS

Retrospective evaluation of CT response and texture patterns in 33 patients (23 female; mean age: 61.2 years, range, 30-85 years) with soft tissue sarcomas treated with pazopanib from October 2008 to July 2017. Response evaluation was based on modified (m)CHOI-criteria and RECISTv.1.1 and classified as partial response (PR), stable disease (SD), progressive disease (PD). The following CT-texture (CTTA)-parameters were calculated: mean, entropy and uniformity of intensity/average/skewness/entropy of co-occurrence matrix and contrast of neighboring-gray-level-dependence-matrix.

RESULTS

Following mCHOI-criteria, 12 patients achieved PR, 7 SD and 14 PD. As per RECISTv.1.1 9 patients obtained PR, 9 SD and 15 PD. Frequent patterns of response were tumor liquefaction and necrosis (n=4/33, 12.1% each). Further patterns included shrinkage and cavitation (n=2/33, 6.1% each). In responders, differences in mean heterogeneity (p=0.01), intensity (p=0.03), average (p=0.03) and entropy of skewness (p=0.01) were found at follow-up whereas in non-responders, CTTA-parameters did not change significantly. Baseline-CTTA-features differed between responders and non-responders in terms of uniformity of skewness (p=0.045). Baseline-CTTA-parameters did not correlate with any morphologic response pattern.

CONCLUSION

Most frequent patterns of response to pazopanib were tumor liquefaction and necrosis. Single CT-textural features show strong association with the response to pazopanib-although limited in relation to specific response patterns.

ADVANCES IN KNOWLEDGE

Tumor liquefication and necrosis are important patterns of response to pazopanib. CT-texture analysis has limited associations with specific response patterns.

RETRACTED: Recommandations françaises du Comité de Cancérologie de l’AFU — Actualisation 2018—2020 : sarcomes rétropéritonéaux French ccAFU guidelines — Update 2018—2020: Retroperitoneal sarcoma

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). Cet article est retiré de la publication à la demande des auteurs car ils ont apporté des modifications significatives sur des points scientifiques après la publication de la première version des recommandations. Le nouvel article est disponible à cette adresse: doi:10.1016/j.purol.2019.01.010. C’est cette nouvelle version qui doit être utilisée pour citer l’article. This article has been retracted at the request of the authors, as it is not based on the definitive version of the text because some scientific data has been corrected since the first issue was published. The replacement has been published at the doi:10.1016/j.purol.2019.01.010. That newer version of the text should be used when citing the article.

CT-response patterns and the role of CT-textural features in inoperable abdominal/retroperitoneal soft tissue sarcomas treated with trabectedin

PURPOSE

To evaluate CT patterns and textural features of soft tissue sarcomas following trabectedin therapy as well as their suitability for predicting therapeutic response.

MATERIAL AND METHODS

A total of 31 patients (18 female, 13 male; mean age, 58.0years; range, 38-79years) with sarcoma under trabectedin as a third-line therapy between October 2008 and July 2017 underwent baseline and follow-up contrast-enhanced CT. Response evaluation was based on modifiedCHOI-criteria and RECIST1.1, classified as partial response(PR), stable disease(SD), progressive disease(PD). For CT-texture analysis (CTTA), mean, entropy and uniformity of intensity/skewness/entropy of co-occurrence matrix (COM) and contrast of neighboring-grey-level-dependence-matrix (NGLDM) were calculated.

RESULTS

Following CHOI-criteria, 9 patients achieved PR, 10 SD and 12 PD. RECIST1.1. classified patients into 5 PR, 15 SD and 11 PD. A frequent (n = 6/31; 19.3%) pattern of response was tumor liquefaction. In responders differences in entropy of entropy-NGLDM(p = 0.028) and uniformity-NGLDM(p = 0.021), in non-responders entropy of average(p = 0.039), deviation(p = 0.04) and uniformity of deviation(p = 0.013) occured between baseline and follow-up. Mean intensity and average were higher when liquefication occured(p = 0.03; p = 0.02), whereas mean deviation was lower(p = 0.02) at baseline compared to other response patterns. Differences in mean(p = 0.023), entropy(p = 0.049) and uniformity(p = 0.023) of entropy-NGLDM were found between responders and non-responders at follow-up. For the mean of heterogeneity a cut-off value was calculated for prediction of response in baseline CTTA (0.12; sensitivity 89%; specificity 77%).

CONCLUSION

A frequent pattern of response to trabectedin was tumor liquefication being responsible for pseudoprogression, therefore modifiedCHOI should be preferred. Single CT-textural features can be used complementarily for prediction and monitoring response to trabectedin.