Personalizing surgical margins in retroperitoneal sarcomas: an update

ABSTRACT

Introduction: Tumor biology, as well as completeness of surgical resection, are two important prognostic factors when treating retroperitoneal sarcoma (RPS). A frontline extended surgical approach is associated with improved local control and possibly improved survival. However, this approach has to be tailored to each histological subtype, as the patterns of growth and recurrence risks vary significantly among them.

Areas covered: We provide a review of the literature in RPS, describing the behavior of each of the five main histologic subtypes: well-differentiated liposarcoma (WDLPS), dedifferentiated liposarcoma (DDLPS), leiomyosarcoma (LMS), solitary fibrous tumor (SFT) and malignant peripheral nerve sheath tumor (MPNST). The prognostic factors relevant to oncologic outcomes of RPS, the role of margins and the importance of local control are discussed. Finally, a histologic specific surgical approach to RPS is provided in detail.

Expert opinion: While tumor-related factors are paramount, the only intervenable predictive factor is extent and quality of surgery. The extended surgical approach has been advocated for previously and again we describe it in more detail, tailored specifically to the tumor subtype. The aim of this approach is to maximize the possibility of achieving a complete resection through a standardized approach based on histologic behavior and site of origin.

KEYWORDS:

• Leiomyosarcoma
• liposarcoma
• outcome
• prognosis
• retroperitoneal sarcoma
• sarcoma
• solitary fibrous tumor
• malignant peripheral nerve sheath tumor
• surgery
• surgical margins
• extended resection
• pelvic sarcoma

Article highlights

• Retroperitoneal sarcomas can be subdivided into the five most common histologic subtypes: WDLPS, DDLPS, LMS, SFT, and MPNST. Each displays a unique pattern of recurrence based on innate biologic aggressiveness.

• The role of surgical margins in RPS has not been established as it has been in the extremity, in part due to the challenges of pathologic assessment of the margin in large tumors. There are no established protocols for assessment of the margins in RPS and because of the nature of the retroperitoneum, surgical resection is often marginal at best.

• We are in an era of personalized medicine and are now seeing the development of nomograms to predict outcomes for retroperitoneal sarcoma patients. Along with this, an understanding of the histologic subtype is required to determine the most appropriate surgical approach, as we know this is a very significant prognostic factor, along with the extent of resection.

• The goal of resection should be aimed at maximizing the chance of microscopically negative margins. This is best achieved through a frontline extended approach, which has been shown to be safe and effective. Studies have demonstrated decreased local recurrence and improved overall survival.

• This is particularly true of WDLPS and G2DDLPS, as local control is the driver of the outcome. This is contrasted to G3DDLPS and LMS, where distant metastases drive the oncologic outcome and an aggressive surgical approach has less impact.

• Due to multifocality, histologic organ involvement and indiscrete borders, we recommend frontline extended resection for all LPS.

• For LMS, the tumor borders are clearly defined and as such the frontline extended approach is not recommended. Instead, the aim should be to resect any adherent or involved structures along with the vessel of origin of the lesion. Ultimately, local control is important, but the high risk of systemic disease will play the largest role in determining the oncologic outcome.

• For SFT, we recommend a multidisciplinary approach when in the pelvis or near critical structures. The goal of resection is to minimize marginality. The approach is different simply because the pattern of tumor growth is different. Tumor borders are easily identifiable and you can save adjacent organ as long as they are not encased, adherent or invaded, but normal tissue is left to cover the lesion.

• The same is true of MPNST, with the exception that this has a much worse prognosis and is considered a high-risk lesion. There is morbidity associated with resection as this requires resection of nerves and often functional impairment.

• The most important first step in personalizing the treatment of RPS is an understanding of the behavior of each tumor subtype and location. We are seeing greater collaboration in the field of sarcoma, which makes the investigation of smaller subgroups easier and faster.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.