Impact of histological subtype on radiological and pathological response after neoadjuvant radiotherapy in soft tissue sarcoma

Myxofibrosarcoma: Outcomes, Prognostic Factors, and Role of Neoadjuvant Radiation Therapy

Purpose

Myxofibrosarcoma (MFS) is a subtype of soft tissue sarcoma with a highly infiltrative growth pattern that leads to a higher risk of inadvertent positive surgical margins and local relapse. Poorly defined tumor margins also pose a challenge for radiation therapy (RT) planning, in terms of treatment volumes and administration of pre- versus postoperative RT. This study aims to evaluate local control and patterns of recurrence in patients with MFS treated with neoadjuvant RT followed by definitive surgical excision.

Methods and Materials

Multiple institutional databases were retrospectively searched for patients diagnosed with MFS between 2013 and 2021 who were exclusively treated with preoperative RT followed by definitive surgery at our institution. The endpoints of the study were defined as local tumor recurrence, distant metastasis, and death after the date of definitive surgery.

Results

Forty-nine patients met the inclusion criteria and were included in the final study. The median age at diagnosis was 67 years, and 71% of patients were male. The tumor was superficially located in 63% of patients, and the mean tumor size at presentation was 7.8 cm. All patients received neoadjuvant RT and completed their planned course of treatment. Neoadjuvant chemotherapy was administered in 22% of patients. Inadvertent excision (IE) before definitive treatment was performed in 25 patients (51%), 84% of which had superficially located tumors. All margins were assessed using frozen section analysis at the time of definitive surgery, and 100% of patients had negative surgical margins, with 25% having no residual tumor. With a median follow-up of 4.7 years, the 5-year local control rate was 87%, and 5-year overall survival was 98%. Tumor depth was associated with distant metastasis (P < .01).

Conclusions

Despite the infiltrative nature of MFS, preoperative RT followed by definitive surgical excision, especially in the setting of a reliable frozen section margin analysis, was associated with excellent local control.

Emerging innovations and advancements in the treatment of extremity and truncal soft tissue sarcomas

In this special edition update on soft tissue sarcomas (STS), we cover classifications, emerging technologies, prognostic tools, radiation schemas, and treatment disparities in extremity and truncal STS. We discuss the importance of enhancing local control and reducing complications, including the role of innovative imaging, surgical guidance, and hypofractionated radiation. We review advancements in systemic and immunotherapeutic treatments and introduce disparities seen in this vulnerable population that must be considered to improve overall patient care.

Non-invasive monitoring of neoadjuvant radiation therapy response in soft tissue sarcomas by multiparametric MRI and quantification of circulating tumor DNA-A study protocol

BACKGROUND

Wide resection remains the cornerstone of localized soft-tissue sarcomas (STS) treatment. Neoadjuvant radiation therapy (NRT) may decrease the risk of local recurrences; however, its effectiveness for different histological STS subtypes has not been systematically investigated. The proposed prospective study evaluates the NRT response in STS using liquid biopsies and the correlation of multiparametric magnetic resonance imaging (mpMRI) with histopathology and immunohistochemistry.

METHODS

Patients with localized high-grade STS, who qualify for NRT, are included in this study.

LIQUID BIOPSIES

Quantification of circulating tumor DNA (ctDNA) in patient blood samples is performed by targeted next-generation sequencing. Soft-tissue sarcoma subtype-specific panel sequencing in combination with patient-specific exome sequencing allows the detection of individual structural variants and point mutations. Circulating free DNA is isolated from peritherapeutically collected patient plasma samples and ctDNA quantified therein. Identification of breakpoints is carried out using FACTERA. Bioinformatic analysis is performed using samtools, picard, fgbio, and the MIRACUM Pipeline.

MPMRI

Combination of conventional MRI sequences with diffusion-weighted imaging, intravoxel-incoherent motion, and dynamic contrast enhancement. Multiparametric MRI is performed before, during, and after NRT. We aim to correlate mpMRI data with the resected specimen's macroscopical, histological, and immunohistochemical findings.

RESULTS

Preliminary data support the notion that quantification of ctDNA in combination with tumor mass characterization through co-registration of mpMRI and histopathology can predict NRT response of STS.

CLINICAL RELEVANCE

The methods presented in this prospective study are necessary to assess therapy response in heterogeneous tumors and lay the foundation of future patient- and tumor-specific therapy concepts. These methods can be applied to various tumor entities. Thus, the participation and support of a wider group of oncologic surgeons are needed to validate these findings on a larger patient cohort.

Pathological and radiological response following neoadjuvant treatments in primary localized resectable myxofibrosarcoma and undifferentiated pleomorphic sarcoma of the extremities and trunk wall

BACKGROUND

To explore the correlation between pathological and radiological response to preoperative treatments and outcome in surgically treated patients with myxofibrosarcoma (MFS) and undifferentiated pleomorphic sarcoma (UPS).

METHODS

All consecutive patients with primary localized MFS and UPS of the extremities and trunk wall surgically treated with curative intent at our center (2005-2021) were included. Clinical data including residual visible tumor (VT%) on surgical specimen and Response Evaluation Criteria in Solid Tumor (RECIST) were retrieved. Kaplan-Meier curves for overall survival and disease-free survival, and cumulative incidence of local relapse and distant metastasis were estimated in a competing risk framework according to RECIST and VT%, overall and by treatment group. Cox and Fine and Gray multivariable models were performed.

RESULTS

Of 693 patients affected by primary MFS and UPS, 233 (66 MFS and 167 UPS) were treated by neoadjuvant chemotherapy (naChT), radiotherapy (naRT), or both (naChT-RT). VT% was ≤5% in 13/46 (28.2%), 24/99 (24.2%), and 40/88 (45.4%) patients, respectively. There were 11/46 (29.7%), 22/99 (22.7%), and 23/88 (26.1%) RECIST partial responses and 18/46 (48.6%), 59/99 (60.8%), and 60/88 (68.2%) RECIST stable disease, respectively. In naChT, a trend for a better survival was observed when VT% ≤5% (p = .09), whereas RECIST partial responses and stable disease had the same outcome. VT% was not associated with outcome in naRT or naChT-RT, whereas RECIST response was.

CONCLUSION

In primary localized MFS and UPS treated with neoadjuvant therapies, VT% seems more relevant than size reduction after naChT, whereas the opposite is true when naRT is administered alone or concurrent to ChT.

Efficacy and Safety of Adjuvant Radiotherapy in Re-excised Soft-tissue Sarcoma After Unplanned Resection

INTRODUCTION

The objective of this study was to evaluate the efficacy and safety of adjuvant radiotherapy (aRT) in patients with soft-tissue sarcoma (STS) re-excised after unplanned tumor resection (UPR).

MATERIALS AND METHODS

From 2000 to 2015, we retrospectively evaluated patients with STS of limb or trunk who underwent post-UPR re-excision in our expert center and received or not aRT.

RESULTS

Median follow-up was 121 months (IQR 94-165). Among the 145 patients, 37 were not treated with aRT (no-RT) and 108 received aRT with a median radiation dose of 50 Gy (IQR 50-60). At 10 years, patients in the aRT and no-RT groups showed a cumulative incidence of local failure (10y-LF) of 14.7% and 37.7%, and a local recurrence-free survival (10y-LRFS) of 61.3% and 45.8%, respectively. Multivariate analysis identified aRT and age ≥70 years as independent predictors of both LF and LRFS, while grade 3 and deep-seated tumor were independent predictors of LRFS. In overall population, 10-year distant metastasis-free survival (10y-DMFS) and overall survival (10y-OS) were 63.7% and 69.4%. In multivariate analyses, age ≥70 years, grade 3, and deep-seated lesion were associated with shorter DMFS and OS. Acute severe adverse events were not significantly increased in aRT group (14.8% vs. 18.1%, P = .85) but dramatically increased if radiation dose exceeded 50 Gy (risk ratio 2.96 compared to ≤50 Gy, P = .04).

CONCLUSION

In STS patients re-excised after UPR, 50 Gy aRT was safe and associated with reduced LF and longer LRFS. It seems to be beneficial even in absence of residual disease or in absence of initial adverse prognostic factors.

Evaluation of Anlotinib Combined with Adriamycin and Ifosfamide as Conversion Therapy for Unresectable Soft Tissue Sarcomas

(1) Background: This study investigated the safety and efficiency of adriamycin and ifosfamide combined with anlotinib (AI/AN) as a neoadjuvant conversion therapy in uSTS. (2) Methods: Patients with uSTS were eligible to receive AI/An, including adriamycin (20 mg/m²/d) and ifosfamide (3 g/m²/d) for the first to the third day combined with anlotinib (12 mg/d) for 2 weeks on/1 week off, all of which combine to comprise one cycle. Surgery was recommended after four cycles of treatment. (3) Results: A total of 28 patients were enrolled from June 2018 to December 2020. The best tumor responses included eight patients with partial responses and 20 with a stable disease. Patients with synovial sarcoma and liposarcoma had a significant decrease in the number of tumors compared with fibrosarcoma (p = 0.012; p = 0.042). The overall response rate and disease control rate were 28.57% and 100%, respectively. In total, 24 patients received surgery, while the rates of limb salvage and R0 resection were 91.67% (n = 22/24) and 87.50% (n = 21/24), respectively. Until the last follow-up visit, the mean PFS and RFS were 21.70 and 23.97 months, respectively. During drug administration, 67.87% of patients had grade ≥3 AEs. No treatment-related death occurred. (4) Conclusions: AI/AN followed by surgery showed favorable efficiency and manageable safety in patients with uSTS. A randomized controlled study with a large cohort should be performed for further investigations.

Correlation of radiological and histopathological response after neoadjuvant radiotherapy in soft tissue sarcoma

BACKGROUND

The aim of this study was to assess the association between radiological and histopathological response after neoadjuvant radiotherapy (nRT) in soft tissue sarcoma (STS), as well as the prognostic value of the different response evaluation methods on the oncological outcome.

METHODS

A retrospective cohort of patients with localized STS of the extremity and trunk wall, treated with nRT followed by resection were included. The radiological response was assessed by RECIST 1.1 (RECIST) and MR-adapted Choi (Choi), histopathologic response was evaluated according to the EORTC-STBSG recommendations. Oncological outcome parameters of interest were local recurrence-free survival (LRFS), disease metastases-free survival (DMFS), and overall survival (OS).

RESULTS

For 107 patients, complete pre- and postoperative pathology and imaging datasets were available. Most tumors were high-grade (77%) and the most common histological subtypes were undifferentiated pleomorphic sarcoma/not otherwise specified (UPS/NOS, 40%), myxoid liposarcoma (MLS, 21%) and myxofibrosarcoma (MFS, 16%). When comparing RECIST to Choi, the response was differently categorized in 58%, with a higher response rate (CR + PR) with Choi. Radiological responders showed a significant lower median percentage of viable cells (RECIST p = .050, Choi p = .015) and necrosis (RECIST p < .001), and a higher median percentage of fibrosis (RECIST p = .005, Choi p = .008), compared to radiological non-responders (SD + PD). RECIST, Choi, fibrosis, and viable cells were not significantly associated with altered oncological outcome, more necrosis was associated with poorer OS (p = .038).

CONCLUSION

RECIST, Choi and the EORTC-STBSG response score show incongruent results in response evaluation. The radiological response was significantly correlated with a lower percentage of viable cells and necrosis, but a higher percentage of fibrosis. Apart from necrosis, radiological nor other histopathological parameters were associated with oncologic outcomes.

Long-term outcomes after definitive radiotherapy with modern techniques for unresectable soft tissue sarcoma

INTRODUCTION

The use of definitive radiotherapy (dRT) in unresectable soft-tissue sarcomas (STS) is still controversial and recent data are scarce. We report clinical results of this therapeutic option.

METHODS

We retrospectively included STS patients treated between 2009 and 2020, with dRT for unresectable or with a measurable residual disease after R2 surgery. Response rate, local failure (LF), progression-free survival (PFS) and overall survival (OS) were evaluated.

RESULTS

116 patients with localized/locally advanced STS were treated from 2009 to 2020, with a median age of 71 years (range 18-92). Most tumors were deep-seated (96.6%), grade 2-3 (85.1%), located in the trunk or extremities (74.2%). Helical tomotherapy, volumetric modulated arc therapy, or stereotactic radiotherapy was performed in 39.7%, 19% and 8.6% of patients, respectively. The median equivalent dose in 2 Gy fractions (EQD2) was 60 Gy (IQR 52-65). At first follow-up, 66 (58.9%) and 25 (22%) patients had stable disease and partial response. After a median follow-up of 54.8 months (IQR 40.3-95.4), 3-year LF, PFS and OS were 43.2%, 16.6% and 34%, respectively. Median OS was 21.4 months (95%CI 14-26). The multivariate analysis identified grade 3 and AJCC T3-T4 stage to be associated with both shorter PFS and OS (all p<0.001). Macroscopically incomplete resection and EQD2 ≥64Gy were associated with better OS (p=0.016 and p=0.007). Acute and late severe adverse events occurred in 24 (19.7%) and 5 (4.3%) patients.

CONCLUSION

In unresectable STS patients, definitive modern radiotherapy is a safe and effective treatment yielding long term control in selected patients.

Neoadjuvant Therapy for Primary Resectable Retroperitoneal Sarcomas-Looking Forward

Simple Summary

This review summarizes the current evidence around neoadjuvant radiotherapy and systemic therapy for retroperitoneal sarcoma (RPS). While surgery is the cornerstone of treatment for these tumors, data from prospective studies, retrospective studies, early phase trials, and—most recently—our first phase III randomized trial for RPS suggest there are clinical scenarios in which neoadjuvant therapy may provide benefit. This review evaluates the STRASS results in the setting of other recent studies, identifies active trials of interest, and suggests future directions of study in this field. The intersection of STRASS and STRASS2 is considered and a summary of current acceptable approaches to neoadjuvant therapy for RPS is provided.

Abstract

The cornerstone of therapy for primary retroperitoneal sarcomas (RPS) is complete surgical resection, best achieved by resecting the tumor en bloc with adherent structures even if not overtly infiltrated. Until recently, trials designed to elucidate the role of neoadjuvant radiation or chemotherapy for RPS have been unable to achieve sufficient enrollment. The completion of the STRASS trial, which explored neoadjuvant radiotherapy for primary resectable RPS, is a major milestone in RPS research, but has prompted further questions about histology-driven treatment paradigms for RPS. Though it was ultimately a negative trial with respect to its primary endpoint of abdominal recurrence-free survival, STRASS produced a signal that suggested improved abdominal recurrence-free survival with neoadjuvant radiotherapy (RT) for patients with liposarcoma (LPS). No effect was seen for leiomyosarcoma (LMS) or high-grade dedifferentiated (DD) LPS, consistent with recent literature suggesting LMS and high-grade DD-LPS have a predominant pattern of distant rather than local failure. These results, along with those from other recent studies conducted at the bench and the bedside, emphasize the importance of a histology-specific approach to RPS research. Recent evidence for patterns of distant failure in LMS and high-grade DD-LPS has prompted the initiation of STRASS2, a study of neoadjuvant chemotherapy for these histologies. As this study unfolds, evidence may emerge for novel systemic therapy options in specific sarcoma histotypes given the explosion in targeted and immunotherapeutic applications over the last decade. This article reviews current and recent evidence around neoadjuvant radiation and chemotherapy as well as avenues for future study to optimize these treatment approaches.