Retroperitoneal Soft Tissue Sarcoma: Emerging Therapeutic Strategies

Abstract

Retroperitoneal soft tissue sarcoma (RPS) is a rare and heterogenous disease for which surgery is the cornerstone of treatment. However, the local recurrence rate is much higher than in soft tissue sarcoma of the extremities since wide resection is usually unfeasible in RPS due to its large size, indistinct tumour borders, anatomical constraints and the thinness of the overlying peritoneum. Local recurrence is the leading cause of death for low-grade RPS, whereas high-grade tumours are prone to distant metastases. In recent decades, the role of emerging therapeutic strategies, such as more extended surgery and (neo)adjuvant treatments to improve oncological outcome in primary localised RPS, has been extensively investigated. In this review, the recent data on the evolving multidisciplinary management of primary localised RPS are comprehensively discussed. The heterogeneity of RPS, with their different histological subtypes and biological behaviour, renders a standard therapeutic 'one-size-fits-all' approach inappropriate, and treatment should be modified according to histological type and malignancy grade. There is sufficient evidence that frontline extended surgery with compartmental resection including all ipsilateral retroperitoneal fat and liberal en bloc resection of adjacent organs and structures, even if they are not macroscopically involved, increases local tumour control in low-grade sarcoma and liposarcoma, but not in leiomyosarcoma for which complete macroscopic resection seems sufficient. Additionally, preoperative radiotherapy is not indicated for all RPSs, but seems to be beneficial in well-differentiated liposarcoma and grade I/II dedifferentiated liposarcoma, and probably in solitary fibrous tumour. Whether neoadjuvant chemotherapy is of benefit in high-grade RPS remains unclear from retrospective data and is subject of the ongoing randomised STRASS 2 trial, from which the results are eagerly awaited. Personalised, histology-tailored multimodality treatment is promising and will likely further evolve as our understanding of the molecular and genetic characteristics within RPS improves.

Keywords: chemotherapy; multimodality management; radiotherapy; retroperitoneal sarcoma; surgery.

Figure 1

A 55-year-old male patient with retroperitoneal sarcoma as the only symptom, weighting 13 kg and measuring 45 cm in maximal diameter, and abdominal distension (A). (B,C): Magnetic resonance imaging showing the tumour. (D): The large tumour at laparotomy. (E): The surgical specimen. (F): The abdominal cavity after resection of the tumour. (G): The medial laparotomy with bilateral subcostal incisions required to resect the tumour completely. (H): Histopathologic examination of the tumour established the diagnosis of a low-grade myxoid liposarcoma. CD34 immunohistochemical staining of a tumour tissue slide highlighting the characteristic delicate thin-walled arborizing and curving capillaries that form a network reminiscent of chicken wirefencing, ×10 magnification ([25] with permission).

Figure 2

A 52-year-old female patient with retroperitoneal sarcoma as the only symptom, measuring 29 cm in maximal diameter, and abdominal distension (A). (B–D): Magnetic resonance imaging showing the tumour. (E): The large tumour at laparotomy. (F,G): The surgical specimen of the tumour with adjacent kidney and adrenal gland. (H): Histopathologic examination of the tumour established the diagnosis of an extra-gastrointestinal stromal tumour. Tissue slide of the tumour demonstrating CD34 immunohistochemical expression, ×40 magnification ([25] with permission).

Figure 3

A 67-year-old male patient with a large retroperitoneal sarcoma and displacement of the left kidney just under the abdominal wall at magnetic resonance imaging (A,B) and extension into the chest at chest computed tomography (C,D). (E): The large tumour at laparotomy. (F): The surgical specimen. (G): The abdominal cavity after resection of the tumour. (H): Histopathologic examination established the diagnosis of a well-differentiated liposarcoma. Tumour slide with H/E stain and ×100 magnification ([25] with permission).

Figure 4

Magnetic resonance imaging of a retroperitoneal inflammatory myofibrosarcoma in a 42-year old male (A,B). Surgical specimen of the retroperitoneal tumour with satellite lesions (C,D) ([25] with permission).