Retroperitoneal soft tissue sarcomas (RPS)

Prof. Ahmed M Badheeb, MD

Retroperitoneal soft tissue sarcomas (RPS)

• 10 and 15 % of (STS). • The most common histologic types are

liposarcoma and leiomyosarcoma.

RPS

• RPS typically produce few symptoms until they are large enough to compress or invade surrounding structures;

• most commonly, they are discovered in asymptomatic patients as an incidental abdominal mass.

The preferred diagnostic work-up

• (CT) scan of the abdomen and pelvis to evaluate the primary site and chest CT to rule out metastatic disease to the lungs.

Complete resection

• Complete resection is the only standard potentially curative treatment (although a small number of selected patients with localized unresectable disease may be amenable to potential cure with charged particle radiation).

• because of the large size and anatomic complexity of the retroperitoneum, microscopically positive resection margins are common, and locoregional recurrence is frequent

Displacement of the small bowel

• Displacement of the small bowel at the time of surgery with omentum or prosthetic spacers in patients who have not received preoperative radiation may facilitate postoperative radiation therapy (RT).

Adjunctive RT

• ●Adjunctive RT reduces the risk of local recurrence, but this benefit has not yet

potentially resectable, small low-grade RPS.

• we prefer initial surgery for most patients with

high-grade or intermediate-grade RPS

• We suggest preoperative RT, rather than initial surgery, for patients with a high-grade or intermediate-grade RPS and for selected patients with a low-grade RPS (eg, one that is large [>10 cm] or appears initially unresectable or borderline resectable) (Grade 2C).

• In this setting, we suggest RT alone rather than chemoradiotherapy, unless the patient is being treated in the context of a clinical trial (Grade 2C).

preoperative biopsy is mandatory

• For patients undergoing nonsurgical initial treatment, a preoperative biopsy is mandatory

low-grade, completely resected (margin-negative) tumor

• •If the patient is seen following resection of an RPS, we do not suggest adjuvant RT for a low-grade, completely resected (margin-negative) tumor (Grade 2C).

Indications : postoperative RT

• intermediate/high-grade histology • positive resection margins • No preoperative RT, postoperative RT is a

reasonable option if this can be done within the tolerance of the adjacent normal tissues.

• This may be facilitated by small bowel displacement at surgery. The main benefit is a reduction in the risk of a disease recurrence.

incomplete (R1 or R2)

• •For patients with an incomplete (R1 or R2) resection, residual microscopic or macroscopic tumor frequently abuts structures or organs that cannot be easily or safely resected. For these patients, we administer a postoperative, small-field supplemental boost dose. Another option, if the surgeon anticipates a positive margin, is intraoperative RT (IORT) for an additional dose of 10 to 15 Gy to areas of grossly evident disease.

Adjuvant chemotherapy

• cannot be considered a standard approach for STS at any site, including the retroperitoneum, and we do not suggest its use outside of the context of a clinical trial (Grade 2B).

Neoadjuvant • •For patients with initially unresectable

disease, neoadjuvant (preoperative) chemotherapy appears to be safe and occasionally induces a radiographic response, which may impact surgical therapy in a few patients.

Preoperative chemoradiotherapy• A role for preoperative chemoradiotherapy in patients

with RPS is not established. There has been interest in this approach for RPS.

• However, in our view, given the lack of data from prospective trials that preoperative chemoradiotherapy is more effective than preoperative RT and the potential for treatment-related toxicity, this approach should only be used for RPS in the context of a clinical trial by clinicians experienced with a chemoradiotherapy approach that had been validated in a prior clinical trial.

Preoperative regional hyperthermia+ systemic chemo

• Although not used in the United States, is another therapeutic option for high-risk primary tumors in parts of the world where it is available (mainly Germany).

• Whether this approach is superior to surgery, with or without RT, or chemoradiotherapy will require a randomized trial.

Local recurrence

• The most significant predictor of outcome following a local recurrence is the resectability of the recurrent disease.

• Reresection should be attempted for an isolated, locally recurrent tumor; approximately 60 percent of such tumors are potentially resectable.

Local recurrenc

• For patients who did not receive RT as part of initial therapy for their sarcoma, we suggest adjunctive RT (Grade 2C).

• For most patients, we prefer preoperative, rather than postoperative, RT

• IORT may also be an option.

unresectable disease recurrence

• Repeated debulking surgery may be a reasonable option for some patients with low-grade liposarcomas, although complete resection is preferred, if feasible.

• For other patients, debulking surgery does not improve long-term survival, and it should not be attempted.

high-dose charged-particle irradiation.Some unresectable RPS:• may be controlled long term (and possibly

cured) with the use of high-dose charged-particle irradiation.

• However, availability of this technology is limited to a few specialized centers.

Preoperative regional hyperthermia+ systemic chemo

• Although not used in the United States, is another therapeutic option for locally recurrent tumors in parts of the world where it is available (mainly Germany).

• Whether this approach is superior to surgery, with or without RT, or chemoradiotherapy will require a randomized trial.

Thank you