Retroperitoneal Sarcoma

Retroperitoneal sarcomas

Retroperitoneal sarcomas (RPS) are rare and heterogeneous group of tumours of soft tissue (mesenchymal) origin. RPS comprise 15% of all soft tissue sarcomas. They are potentially malignant and can grow to very large tumours within the abdomen and pelvis. Therefore, they usually present late with symptoms of obstruction and pain. Obstructive symptoms depend on which organ or structure is involved. They include the ureter, bladder, bowel and nerves. Management of patients with RPS is a challenge especially when they are malignant and involve these vital organs and structures. The therapeutic strategies include surgical resection, radiotherapy and chemotherapy or a combination of these. The dilemma is which of these are the best modality, which combination and in which order is the optimal treatment and which ones in this heterogenous group will respond to such therapies.

Surgical margins, like other malignancies, are crucial and determine outcomes such as survival and recurrence rates. Due to the location of RPS, surgical margin of normal tissue may not be possible due to the limitations of the anatomy. Therefore, multivisceral resections are advocated for large retroperitoneal sarcomas, especially those with negative prognostic features, such as dedifferentiation components in a liposarcoma to achieve complete resection and improve survival.

The histopathologic spectrum of sarcomas is broad due to embryonic mesenchymal cells with the ability to mature into different types of muscles (striated skeletal and smooth muscle), adipose and fibrous tissue, bone, and cartilage, among other tissues and hence a heterogenous group. The most common histological subtype of RPS are liposarcomas.

Recurrence can also occur in distant organs and is usually hematogenous spread to predominantly to the lung, though metastatic patterns are also linked to specific sarcoma histology.  Overall, spread to regional nodes is infrequent for soft tissue sarcomas.

A number of prognostic factors have been identified in patients with soft tissue sarcoma, the most important of which are histologic grade, tumor size and pathologic stage at the time of diagnosis. As previously mentioned, local recurrence is a significant prognostic factor influencing survival, and hence the optimal adjunct treatments for RPS need to take these prognostic factors into account. Radiotherapy is the most widely utilized adjunct to surgery in the aim to reduce locoregional recurrence but at present, data supporting the use is also limited and the increasing use of radiotherapy has largely been extrapolated from its established role for soft tissue extremity sarcomas. A recently published randomized study, (EORTC-62092 STRASS I Trial), reported no benefit to recurrent disease free survival with addition the of pre-operative radiotherapy. New chemotherapy agents are currently being utilized and but more data is required for long term outcomes. A collaboration of sarcoma units within the European group and also including other non-European centres, such as in Australia, Royal Prince Alfred and Chris O’Brien Lifehouse Cancer Centre have been invited to participate in the EORTC 1809 STRASS II Trial. This phase III randomized study will investigate the efficacy of neoadjuvant chemotherapy for dedifferentiated liposarcomas and leiomyosarcomas.
In the future, collaborative databases and research will help find the optimal management strategies for the different subtypes of RPS.

Before Treatment

• Staging the Disease – need to perform CT, MRI and PET/CT scans to assess the tumour and exclude distant spread (metastatic disease).
• CT guided biopsy – A biopsy for confirmation of the type of sarcoma is usually required before treatment. This is usually performed with a CT scan.
• Multidisciplinary (MDT) meeting — Planning for the most appropriate treatment modality for patients, with the review of the radiology and histology, amongst medical oncologists, radiation oncologists, surgeons and sarcoma CNCs (clinical nurse specialists).
• Consultations – Consultations with the various specialists to discuss and commence treatment. Surgery may require a collaboration of subspecialities including colorectal, upper GI and vascular, and orthopaedic surgeons, gynae-oncologists and urologists.

Types of Operations

Retroperitoneal sarcomas can occur in the abdomen, pelvis or both. Depending on which organs or structures are involved, a collaborative approach to surgery is made at the time of the MDT meeting. Surgery can range from limited to maximally invasive resections, such as pelvic exenterations or multi-visceral (multiple organs or structures such as major veins, arteries, muscles and nerves) resections for abdominal RPS. The most common organs or structures that require resection include the kidney, bowel, and posterior abdominal wall muscles.

Indications

The indications and surgical management for each patient may differ. Please consult your surgeon for more information or any questions you may have.

Clinical staff

The Retroperitoneal sarcoma service at RPA are made up of the following staff:
Surgeons
Medical Oncologist
Radiation Oncologist
Radiologist
Pathologist
Retroperitoneal Sarcoma Clinical Nurse Consultant
Retroperitoneal Sarcoma Research Officer
Other Staff
Medical Team
Other Consultants (Urology, Orthopaedic, Plastics, Vascular)
Surgical Fellows
Surgical Registrars
Senior Resident Medical Officers (SRMO)
Interns
Oncologists

Nursing Team

Nurse Unit Manager (NUM)
Retroperitoneal Sarcoma Clinical Nurse Consultant
Registered Nurses (RN) / Enrolled Nurses (EN)
Operating Theatre Nurses
Intensive Care Unit Nurses

Research

The Retroperitoneal Sarcoma Service currently has two studies running including:

• SPARC Database – ‘Sarcoma of the Pelvis, Abdomen or Retroperitoneum Collaboration Database’ collects clinical and treatment information from patients who have been diagnosed with a sarcoma located in either the pelvis, abdomen and/or the retroperitoneum. The study aims to understand the long-term quality of life, use of health services, and clinical outcomes of patients diagnosed with sarcoma.
• RESAR – ‘REtroperitoneal SArcoma Registry’ is the prospective collection of primary retroperitoneal sarcoma patient data, for the TransAtlantic Retroperitoneal Sarcoma Working Group. This study collects clinical and treatment information including radiological and pathological data from patients with a new diagnosis of retroperitoneal sarcoma at a number of centres worldwide including RPAH and COBLH.