Retroperitoneal Sarcomas—An SOS to Colleagues in Europe

Surgical management of retroperitoneal and pelvic sarcomas

Management of retroperitoneal sarcomas presents technical and oncological challenges. Imaging is crucial for diagnosis and to define local tumor extent. Complete gross resection at initial presentation is the best chance for cure, but there is controversy as to how this can be best achieved. There is a long-term risk of local recurrence, which is best treated with repeat resection if feasible. The roles of radiation and chemotherapy remain undefined.

The effect of neoadjuvant radiation therapy on perioperative outcomes among patients undergoing resection of retroperitoneal sarcomas

BACKGROUND

Neoadjuvant radiation therapy (RT) has several theoretical benefits in the treatment of retroperitoneal sarcoma (RPS), but concerns remain about treatment toxicity and perioperative morbidity. There are limited data regarding its effect on perioperative outcomes, most of which come from small, single-institution series. The purpose of this study was to evaluate the short-term (30-day) postoperative morbidity and mortality associated with neoadjuvant RT following resection of RPS.

METHODS

The 2005-2011 National Surgical Quality Improvement Program Participant User File was queried for patients undergoing RPS resection. Subjects were stratified by use of neoadjuvant RT. Perioperative variables and short-term 30-day outcomes were compared. Groups were then propensity matched using a 2:1 nearest-neighbor algorithm and multivariable logistic regression was performed to assess neoadjuvant RT as a predictor of short-term 30-day outcomes.

RESULTS

A total of 785 patients were identified. Neoadjuvant RT was administered to 71 (9.0%). Patients who received neoadjuvant RT were slightly younger (56 vs. 62 years, p < 0.001), but otherwise the groups were similar. After propensity matching, all baseline characteristics were highly similar. Median operative time was longer in the neoadjuvant RT group (279 vs. 219 min, p < 0.01), but there were no differences in mortality (1.4 vs. 2.1%, p = 0.71), major complications (28.2 vs. 25.2%, p = 0.69), overall complications (35.2 vs.33.2%, p = 0.83), early reoperation (5.6 vs. 7.4%, p = 0.81), or length of stay (7 vs. 7 days, p = 0.56). Following further adjustment with logistic regression, we confirmed that there were no differences in 30-day mortality or morbidity between patients who did and did not receive neoadjuvant RT.

CONCLUSIONS

Neoadjuvant RT does not appear to increase short-term (30-day) morbidity or mortality following resection of RPS. Continued investigation is needed to better define the role for radiation therapy among patients with this disease.

Management of recurrent retroperitoneal sarcoma

Approximately 15% of soft tissue sarcomas are retroperitoneal. The occult location and anatomic complexity results in local recurrences in the majority of patients. Predictors of recurrence include histological subtype, completeness of resection, and the hospital case volume. The most significant predictor of outcome following local recurrence is the resectability of the recurrent disease. An understanding of the implication of tumor biology on outcomes is essential in determining optimal management for patients with recurrent retroperitoneal sarcoma.

Current concepts and future perspectives in retroperitoneal soft-tissue sarcoma management

Retroperitoneal soft-tissue sarcomas are complex, heterogeneous cancers requiring expert multidisciplinary care. They can occur anywhere in the retroperitoneal abdominal or pelvic space. Usually large at presentation they present particular challenges for both local treatment and systemic control. The most common adult subtypes are liposarcomas and leiomyosarcomas, followed by pleomorphic sarcoma/malignant fibros histiocytoma (an entity not always easily distinguishable from dedifferentiated liposarcoma). A variety of additional histotypes may also be observed, but are uncommon in the retroperitoneum, either because of intrinsic rarity or because they are usually found in other anatomic sites. The underlying biology varies according to the different histotypes. Pediatric subtypes mainly comprise extraskeletal Ewing sarcoma/pPNET and alveolar rhabdomyosarcoma. Surgery is critical for controlling these tumors and requires an aggressive approach. It may also provide useful palliation for patients with advanced slow-growing disease. Radiotherapy has acquired a definite position in attempting to reduce relapse, although prospective trials of adjuvant or neoadjuvant radiotherapy are needed. Chemotherapy has a limited role in the adjuvant setting for most forms of retroperitoneal sarcoma (excluding pediatric subtypes), but has an increasing role in advanced disease. Novel targeted therapeutic agents that target specific amplification or translocation products offer promise for subsets of these diseases.

Current concepts in the management of retroperitoneal soft tissue sarcoma

Soft tissue sarcomas (STS) in the retroperitoneum are usually diagnosed at the late stages. Surgery is the mainstay of treatment. The technique of resection is standardized. After dissection of the retroperitoneal blood vessel, a retroperitoneal plane of dissection adjacent to the spinal foramina is established in between the layers of the abdominal wall. Complete resection with tumor-free resection margins is the primary goal in retroperitoneal sarcoma surgery. Preoperative assessment of pathoanatomical growth patterns with respect to retroperitoneal vascular structures--as well as to visceral and retroperitoneal organs--influences surgical strategies and thus the surgical outcome. Blood vessel replacement and a multivisceral en bloc approach improve the quality of resection. Blood vessel involvement is stratified in type I (arterial and venous involvement), type II (arterial involvement), type III(venous involvement), and type IV (no vascular involvement). Adjuvant and neoadjuvant treatment options (chemotherapy, targeted therapy, and radiation therapy) are currently being investigated. A prospective randomized phase III trial has shown a positive effect of neoadjuvant chemotherapy combined with regional hyperthermia in disease-free survival, response rate, and local control. Subsets of liposarcomas (myxoid and round cell type) are selectively responsive to novel drugs, such as trabectedin, a DNA-binding agent. Radiotherapy is applied in higher-grade locally advanced retroperitoneal STS. The optimal technique of delivering radiotherapy remains to be determined. The restricted number of patients with retroperitoneal STS and unsatisfying results in local tumor control and long-term survival indicate the need for multi-institutional cooperative studies. An international effort is required to improve the evidence level on multimodal treatment algorithms.