Retroperitoneal soft tissue sarcomas: a treatment challenge and a call for randomized trials

IOeRT in retroperitoneal sarcoma: Towards more organ preservation with comparable oncological outcomes

BACKGROUND

Retroperitoneal sarcomas (RPS) present a surgical challenge with high rates of local recurrence (LR). We investigated the role of intraoperative electron radiotherapy (IOeRT) in reducing LR after surgical resection of RPS.

METHODS

A retrospective analysis of all patients who underwent surgical resection for RPS between 2014 and 2021 at a tertiary academic referral center (n = 172). Patients included underwent surgical resection of their RPS and received IOeRT (n = 36) and were compared by case control matching to patients with similar tumor characteristics (recurrence status and tumor grade) that did not receive IOeRT (n = 36).

RESULTS

The median length of hospitalization was 8 days (range, 4-34) in the IOeRT group and 10 days (range, 2-42) in the non-IOeRT group (p = 0.25). The mean operating room (OR) time was 4h (±1.3) and 4h (±1.9) in the IOeRT and non-IOeRT groups respectively, (p = 0.37). Complete resection with R0 margins was achieved in 30 patients (83.3%) and 24 patients (66.6%) in the IOeRT and non-IOeRT groups, respectively (p = 0.1). R1 resection was achieved in 6 patients (16.6%) and 12 patients (33.3%) respectively, (p = 0.1). The resected organ weighted score was significantly different between the groups; score 0 observed in 19 (52.7%) patients in the IOeRT group and 3 (8.3%) in the non-IOeRT group (p < 0.001), score 1 observed in 7 (19.4%) in the IOeRT group and 17 (47.2%) in the non-IOeRT group (p = 0.012). The rate of severe complications (CD score>3) did not differ between the groups, 5 (13.8%) patients in the IOeRT group and 9 (25%) patients in the non-IOeRT group (p = 0.23). No radiation associated complications were noted. The 2-year local recurrence free survival (LRFS) was 75.9% in the IOeRT group and 60.3% in the non-IOeRT group (p = 0.4). The 2-year IOeRT field recurrent free survival (IRFS) was 88.4% in the IOeRT group and 60.3% in the non-IOeRT group (p = 0.04).

CONCLUSIONS

The use of IOeRT did not increase the rate of surgical complications and was associated with superior local control in the radiation field, improved organ preservation without an impact on overall survival.

Case report and literature review: Conversion surgery for initially unresectable huge retroperitoneal liposarcoma after preoperative radiotherapy

Background

Retroperitoneal liposarcoma (RPLS) is a rare malignancy that is notorious for recurrence. Surgical resection with clean margin is the current treatment of choice. However, owing to the large retroperitoneal space, RPLSs often grow to significant sizes before being diagnosed. Neoadjuvant and adjuvant therapies have potentials to improve long term treatment outcome.

Case presentation

A 55-year-old Han Chinese male presented to the general surgery department with a one-year history of abdominal fullness and a one-week history of palpable right inguinal mass. At first, he was diagnosed with incarcerated inguinal hernia. However, abdominal computer tomography (CT) and biopsy confirmed his final diagnosis to be retroperitoneal well-differentiated liposarcoma, cT2bN0M0, stage IIb. The tumor, which measured 44.5cm in maximum diameter, was too large for primary surgical resection. Neoadjuvant radiotherapy with 70 Gy in 35 fractions was delivered to the tumor, which shrunk the target volume from 6300 cc to 4800 cc, as observed in the middle of the radiotherapy course. The right testicular mass also received 70Gy/35Fx. Conversion surgery was performed after radiotherapy. Unfortunately, due to residual tumor, adjuvant chemotherapy consisting of AIM (ifosfamide, Mesna, and doxorubicin) and MAID (Mesna, doxorubincin, ifosfamide, and dacarbazine) regimens were administered sequentially. Afterward, debulking surgery was conducted, plus another 18 cycles of ifosfamide monotherapy when residual tumor was still seen on CT. Since the completion of ifosfamide chemotherapy, the patient has been cancer free with no evidence of tumor recurrence for more than 26 months.

Conclusion

Despite conflicting evidence in the literature, our case supports the use of high dose neoadjuvant radiotherapy and adjuvant chemotherapy in treating large, unresectable RPLSs. It also highlights the importance of using individualized, multidisciplinary approach in achieving cure for large, unresectable rare tumors.

Role of Radiation Therapy for Newly Diagnosed Retroperitoneal Sarcoma

OPINION STATEMENT

Soft tissue sarcomas (STS) are rare, aggressive, and heterogenous tumors, comprising approximately 1% of adult cancers with over 50 different subtypes. The mainstay of treatment for retroperitoneal sarcomas (RPS) includes surgical resection. The addition of radiation therapy (RT), either preoperatively or postoperatively, has been used to potentially decrease the risk of local recurrence. The recently published results from STRASS (EORTC-STBSG 62092-22092), which randomized patients to receive or not receive preoperative radiation, indicate no abdominal recurrence-free survival benefit (primary endpoint) nor overall survival benefit to date from the addition of preoperative RT prior to surgical resection in patients with RPS. Keeping in mind caveats of subgroup analyses, the data show a significant reduction in local recurrence with radiation therapy in resected patients and non-significant trends toward improved abdominal recurrence-free survival in all patients and improved local control and abdominal recurrence-free survival in patients with liposarcoma and low-grade sarcoma. Given the high rate of local failure with surgery alone, it is possible that higher RT dose and/or selective RT dose painting may improve outcomes. Prior to treatment, the authors encourage multidisciplinary review and discussion of management options at a sarcoma center for patients with RPS. Selective use of RT may be considered for patients at high risk of local recurrence.

Retroperitoneal soft tissue sarcoma: low-dose neoadjuvant radiation therapy followed by surgery with or without intraoperative radiotherapy and adjuvant radiation therapy

BACKGROUND

We describe the clinical history, outcome, and toxicity of five patients with high-grade retroperitoneal soft tissue sarcoma (RSTS) who were treated with neoadjuvant low-dose radiotherapy (RT) followed by resection with or without intraoperative radiotherapy (IORT), followed by adjuvant RT. We aim to provide additional evidence for the various treatment options that exist for this rare tumor entity.

METHODS

Most patients presented with mild abdominal symptoms. Diagnosis was confirmed by biopsy. Additional imaging was done by sonography, magnetic resonance imaging (MRI), and/or positron emission tomography (PET)/computed tomography (CT). All patients were treated with neoadjuvant RT of 19.8 Gy in 1.8-Gy fractions followed by resection and postoperative RT up to 45 Gy with a median interval between resection and start of postoperative RT of 5 weeks. Two patients received additional IORT. Median follow-up was 61 months.

RESULTS

One patient developed a local recurrence that was diagnosed 30 months after the start of the first therapy. He was treated with a salvage resection and had no evidence of disease at the last follow-up. Another patient developed a right-sided RSTS on the contralateral side from the primary radiation field with pelvic bone infiltration 56 months after the start of RT. He was treated again by RT and resection and was without evidence of disease at last follow-up. Radiotherapy was well tolerated without major toxicity.

CONCLUSION

The treatment of RSTS by low-dose neoadjuvant RT, resection with IORT and adjuvant RT seems to be a feasible and effective treatment approach. Further studies comparing neoadjuvant with adjuvant RT are necessary to find the best treatment option.

Phase 1 trial of preoperative image guided intensity modulated proton radiation therapy with simultaneously integrated boost to the high risk margin for retroperitoneal sarcomas

PURPOSE

To conduct phase 1 and 2 trials with photon intensity modulated radiation therapy and intensity modulated proton therapy (IMPT) arms to selectively escalate the retroperitoneal sarcoma preoperative radiation dose to tumor volume (clinical target volume [CTV] 2) that is judged to be at a high risk for positive margins and aim to reduce local recurrence. We report on the IMPT study arm in phase 1.

METHODS AND MATERIALS

Patients aged ≥18 years with primary or locally recurrent retroperitoneal sarcoma were treated with preoperative IMPT, 50.4 GyRBE in 28 fractions, to CTV1 (gross tumor volume and adjacent tissues at risk of subclinical disease) with a simultaneous integrated boost to CTV2 to doses of 60.2, 61.6, and 63.0 GyRBE in 28 fractions of 2.15, 2.20, and 2.25 GyRBE, respectively. The primary objective of the phase 1 study was to determine the maximum tolerated dose to CTV2, which will be further tested in the phase 2 study.

RESULTS

Eleven patients showed increasing IMPT dose levels without acute dose limiting toxicities that prevented dose escalation to maximum tolerated dose. Acute toxicity was generally mild with no radiation interruptions. No unexpected perioperative morbidity was noted. Eight months postoperatively, one patient developed hydronephrosis that was treated by stent with ureter dissected off tumor and received 57.5 GyRBE. Retained ureter(s) was (were) subsequently constrained to 50.4 GyRBE without further problem. With an 18-month median follow-up, there were no local recurrences.

CONCLUSIONS

IMPT dose escalation to CTV2 to 63 GyRBE was achieved without acute dose limiting toxicities. The phase 2 study of IMPT will accrue patients to that dose. Parallel intensity modulated radiation therapy phase 1 arm is currently accruing at the initial dose level. Ureters that undergo a high dose radiation and/or surgery are at risk for late hydro-ureter. Future studies will constrain retained ureters to 50.4 GyRBE to avoid ureteral stricture.

Neoadjuvant radiotherapy for retroperitoneal sarcoma: A systematic review

BACKGROUND AND OBJECTIVES

The multi-modal treatment of retroperitoneal sarcoma has seen increased use of neoadjuvant radiation. However, its effect on local recurrence and survival remain controversial. We aimed to synthesize and evaluate the literature.

METHODS

The review was conducted according the recommendation of the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) group with pre-specified inclusion and exclusion criteria.

RESULTS

Of 8,701 citations collected, 15 articles reported on 464 patients. The median age was 56 years (45-64). The predominant histological subtypes were liposarcoma (51.54%) and leiomyosarcoma (23.26%). Tumor differentiation composed of 37.1% well-, 12.8% moderate-, 46.0% poorly-, and 4.1% undifferentiated. Most studies featured external beam radiation therapy (EBRT) treatment regimen with some who included patients treated with IMRT instead. Median follow-up averaged 41.4 months (19-106 months). Median 5-year OS, PFS, and LRR rates were 58%, 71.5%, and 25%. Using the NCI CTCAE, toxicities from Grade 1 (Mild) through Grade 5 (death) were experienced by 18.8%, 10.2%, 16.3%, 0.7%, and 1.6% of patients.

CONCLUSIONS

NART is a safe to use for RPS, but its effect toward survival and local control remains unclear. Without randomized control trials, common reporting criteria for pro- and retrospective studies are needed to allow comparison between studies. J. Surg. Oncol. 2016;113:628-634. © 2016 Wiley Periodicals, Inc.

Role of radiation therapy for non-extremity soft tissue sarcomas

BACKGROUND

Negative surgical margins are uncommon for non-extremity soft tissue sarcomas. Radiation therapy is usually recommended to improve local control; however, appropriate RT dosing is challenging due to nearby dose-limiting normal structures.

MATERIAL AND METHODS

Comprehensive literature search using PubMed (March 2014).

RESULTS

Data suggest radiation therapy is an important modality in maximizing local tumor control in non-extremity sarcomas.

CONCLUSION

The literature supports the use of RT to improve local control for non-extremity soft tissue sarcomas.

Radiotherapy and surgery-an indispensable duo in the treatment of retroperitoneal sarcoma

The authors undertook a systematic review to designate the role that radiotherapy (RT) might play in the treatment of retroperitoneal sarcomas. Correlating with recent literature, the objective of this review was to evaluate whether there was enough evidence for the authors to develop an institutional treatment protocol concerning the use of RT in the treatment of retroperitoneal sarcoma. Furthermore, this was a call for surgeons to talk to radiation oncologists before performing surgery. The 2 objectives of this review were: 1) to determine the benefit of RT in terms of local control and/or survival in the treatment of retroperitoneal sarcomas and 2) to discover the optimal timing of RT in the treatment sequence. A computerized literature search was performed in the PubMed database, the Cochrane Library database, and reference lists; and journals also were searched by hand to identify all retrospective and prospective reports published since 1998 relating to RT treatment of adult retroperitoneal sarcoma. Mainly, analyses were sought that were based on a 5-year local control rate (LCR), 5-year disease-free survival, and 5-year overall survival (OS). If only 2 years follow-up were available, then the authors also noted this outcome. Toxicity data were collected and analyzed separately. The synthesis of the literature was based on 9 prospectively nonrandomized studies and 10 retrospective studies that, together, reviewed a total of 1426 patients. The 5-year LCR varied from 27% to 62%, and the results from other reports fell in between those values. The 5-year OS rate ranged from 12% to 90%, and complete resection and tumor grade were the most important prognostic factors in most studies. This review resulted in 7 recommendations concerning the use of RT in the treatment of retroperitoneal sarcoma. The authors concluded that there is good evidence from multiple single-institutions studies that RT improves the LCR in patients with retroperitoneal sarcoma. Until now, there has not been a translation of this approach into survival benefit. The current results indicated that preoperative external-beam RT followed by radical surgery seems to be the preferred sequence, and adding intraoperative RT is a safe procedure for dose escalation in the upper abdomen.

Long-Term Outcomes After Radiotherapy for Retroperitoneal and Deep Truncal Sarcoma

PURPOSE

To determine the long-term outcomes after multimodality treatment of retroperitoneal, pelvic, and deep truncal sarcomas and to identify the factors associated with local control (LC), distant metastasis (DM), and overall survival (OS).

METHODS AND MATERIALS

A total of 85 patients with retroperitoneal, pelvic, and deep truncal sarcomas were treated with radiotherapy (RT) between 1987 and 2005. A retrospective analysis of LC, DM, and OS was conducted using log-rank and Cox regression statistical methods.

RESULTS

The 2- and 5-year LC, DM, and OS rates were 66% and 51%, 38% and 58%, and 70% and 34%, respectively. Negative surgical margins and a higher radiation dose were associated with greater LC rates on both univariate and multivariate analyses, and female gender was significantly associated with greater LC on multivariate analysis only. None of the analyzed risk factors was significantly associated with DM, although patients with high-grade tumors showed a trend toward an increased risk of DM. Gross residual disease after resection and high tumor grade were associated with worse OS rates on univariate and multivariate analyses, and male gender was significantly associated with worse OS on multivariate analysis only. A time-dependent analysis of LC in relation to DM demonstrated that patients with local failure had a hazard ratio of 19.7 for DM compared with patients without local failure (p < 0.0001). Of the 85 patients, 5 and 8, respectively, had clinically significant acute and late toxicity.

CONCLUSION

The results of this study emphasize the importance of LC in patients with retroperitoneal sarcoma. Radiation dose escalation or radiosensitization strategies to enhance LC are warranted.

Intensity modulated radiation-therapy for preoperative posterior abdominal wall irradiation of retroperitoneal liposarcomas

PURPOSE

Preoperative external-beam radiation therapy (preop RT) in the management of Retroperitoneal Liposarcomas (RPLS) typically involves the delivery of radiation to the entire tumor mass: yet this may not be necessary. The purpose of this study is to evaluate a new strategy of preop RT for RPLS in which the target volume is limited to the contact area between the tumoral mass and the posterior abdominal wall.

METHODS AND MATERIALS

Between June 2000 and Jan 2005, 18 patients with the diagnosis of RPLS have been treated following a pilot protocol of pre-op RT, 50 Gy in 25 fractions of 2 Gy/day. The Clinical Target Volume (CTV) has been limited to the posterior abdominal wall, region at higher risk for local relapse. A Three-Dimensional conformal (3D-CRT) and an Intensity Modulated (IMRT) plan were generated and compared; toxicity was reported following the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events v3.0.

RESULTS

All patients completed the planned treatment and the acute toxicity was tolerable: 2 patients experienced Grade 3 and 1 Grade 2 anorexia while 2 patients developed Grade 2 nausea. IMRT allows a better sparing of the ipsilateral and the contralateral kidney. All tumors were successfully resected without major complications. At a median follow-up of 27 months 2 patients developed a local relapse and 1 lung metastasis.

CONCLUSIONS

Our strategy of preop RT is feasible and well tolerated: the rate of resectability is not compromised by limiting the preop CTV to the posterior abdominal wall and a better critical-structures sparing is obtained with IMRT.

Use of Tissue Expanders and Pre-operative External Beam Radiotherapy in the Treatment of Retroperitoneal Sarcoma

INTRODUCTION

We report our experience of treating retroperitoneal sarcoma (RPS) using pre-operative external beam radiotherapy (EBRT) in combination with radical resectional surgery from 1990 to 2005.

METHODS

Twenty-eight primary and 10 recurrent tumors were identified from a prospective database.

RESULTS

The resection rate was 71% overall; 82% in primary (23/28) and 40% (4/10) in recurrent cases. EBRT was administered preoperatively in 25 patients, postoperatively in 1, and palliatively in 11. In 33 patients a saline-filled tissue expander was inserted into the abdomen before radiotherapy to displace small bowel from the radiation field. 4,500-5,000 cGy was administered in fractions of 180-200 cGy over a 5-week period; surgery followed 6-8 weeks later. Expander insertion was associated with minimal morbidity; 31/37 patients received a dose of 4,000 cGy or more (median 4,650 cGy). Median resected tumor diameter was 13 cm, and a median of three adjacent organs was resected per patient. Complete macroscopic resection was achieved in 25/27 patients (93%); R0 in 9 (33%) and R1 in 13 (48%) (microscopic margins unclear in 5). There was no postoperative mortality. Tumors were high-grade in 20 patients, low-grade in 14 and ungraded in 4. Actuarial 5- and 10-year survival for all patients was 74 and 60%. For operable primary tumors, the 5-year survival and disease-free rates were 90 and 80%. In four patients with operable recurrent tumors, median disease-free interval was 91 months (27-160). In the 11 inoperable cases, median survival after radiotherapy was 48 months (9-77).

CONCLUSIONS

We conclude that a combination of pre-operative tissue expander placement, high-dose EBRT and radical resectional surgery can achieve acceptable morbidity, extended survival and low long-term recurrence in patients with RPS.

STATISTICS

Median (interquartile range).

Dosimetric comparison of helical tomotherapy treatment and step-and-shoot intensity-modulated radiotherapy of retroperitoneal sarcoma

PURPOSE

To compare step-and-shoot intensity-modulated radiation therapy (SAS-IMRT) and helical tomotherapy (Tomo) dosimetry plans for patients who have received adjuvant radiation therapy for retroperitoneal sarcomas (RSTS).

METHODS AND MATERIALS

A retrospective review was performed for seven patients who received either SAS-IMRT or Tomo as adjuvant radiation therapy for RSTS. In each case, a treatment plan of the other modality was generated so that SAS-IMRT and Tomo could be compared.

RESULTS

The average percentage of clinical target volume (CTV) that received less than the prescription dose was 1.4% for Tomo compared to 3.8% for SAS-IMRT. Both SAS-IMRT and Tomo plans provided comparable and significant reductions in volume of small bowel receiving greater than 45 Gy compared to simple opposing standard radiation fields. For the ipsilateral kidney, Tomo significantly reduced the volume of kidney that received at least 15 Gy (average 22% for Tomo vs. 56% for SAS-IMRT).

CONCLUSION

Both SAS-IMRT and Tomo can encompass the large CTV often required for patients with RSTS, although Tomo provides superior dose uniformity. Both SAS-IMRT and Tomo can minimize the volume of small bowel receiving greater than 45 Gy. Tomo was superior to SAS-IMRT in minimizing the volume of ipsilateral kidney irradiated to greater than 15 Gy when the CTV is adjacent to a kidney. Dose escalation and target margin expansion may thus become realistic possibilities.

Emerging treatments for soft tissue sarcoma of adults

Soft tissue sarcomas are a heterogeneous group of malignancies arising from mesenchymal tissues. Patients can present with a localised tumour (primary or local recurrence) at different sites (e.g., extremity, abdomen) or metastatic disease, which may require different treatment strategies. Is the surgical resection of a localised sarcoma enough or is it better to give an additional treatment like adjuvant and/or preoperative radiotherapy and/or chemotherapy? Which chemotherapy should be selected in the first or second line situation? Do new treatment options exist, such as targeted therapies? This review provides answers to some of these questions. To decide on consecutive treatment steps, it is important to know as many relevant factors as possible at first presentation. Therefore, the first part of this review discusses the specific characteristics and prognostic factors of importance for treatment planning. A short summary of current therapy strategies and existing standards is then given. The main body of the review summarises information on new and emerging clinical compounds for patients with soft tissue sarcoma of adults, including recent developments of targeted therapy.

Recent advances in radiotherapy for soft-tissue sarcoma

The use of radiotherapy in soft-tissue sarcoma continues to evolve. This review focuses on how current management is influenced by the most recent publications in the field. In particular, experience of patients treated without radiotherapy permits guidelines to be established that define a subset of patients who do not need radiotherapy to achieve sarcoma cure with good function. Strategies for radiotherapy delivery are discussed, including the most recent prospective results from a trial of preoperative and postoperative radiotherapy, with particular emphasis on randomized data. Also, the definitions for adequacy of surgical excision and the ability to achieve high rates of local control when margins are minimally positive are integrated into a planned approach. The difficult problem of retroperitoneal sarcoma is discussed, as are chemoradiotherapy protocols that may enhance local and systemic outcome. Finally, the potential for image-guided radiotherapy, enhanced targeting, and better radiotherapy delivery in the contemporary era is addressed.