Radiation Therapy for Treatment of Soft Tissue Sarcoma in Adults: Executive Summary of an ASTRO Clinical Practice Guideline

The Landmark Series: Neoadjuvant Radiotherapy in Extremity Soft Tissue Sarcoma-The Way to Hypofractionation

For patients with nonmetastatic soft tissue sarcoma (STS) who are at high risk of local recurrence, the standard of care for limb-conserving local management is combined radiotherapy and surgery. Radiotherapy for STS entails 5 weeks of conventionally fractionated radiotherapy (25 × 2 Gy) preoperatively or 6 or more weeks postoperatively. There is growing interest in the use of preoperative hypofractionated regimes, viz. shorter courses with higher daily doses, for STS. Recent studies have investigated ultrahypofractionation (UHF, ≥ 5 Gy per fraction) and moderate hypofractionation (MHF, > 2 Gy but < 5 Gy per fraction) for STS. Regimens that are designed to be isoeffective for tumor control indeed result in equivalent local relapse-free survival. However, as the daily dose increases, the impacts to normal tissues and potential for toxicities increase owing to differences in fraction-size sensitivity between STS and normal tissues (e.g., skin, subcutaneous tissue, vascular structures, and bone). This article reviews the key studies informing the debate about hypofractionation for STS. We evaluate the current data that reveal relatively small patient cohorts, short follow-up time, and inconsistent toxicity reporting. A randomized, controlled investigation of conventional fractionation, MHF, and UHF is needed. The current phase 2 data confirm that any such study should have co-primary endpoints of both local relapse-free survival as well as immediate- and long-term toxicities because the fundamental question being investigated with significant increase in daily fraction size while maintaining isoeffective total dose (~ 50 Gy equivalent) is: what are the dose impacts to late-responding normal tissues that may result in decrements to physical functioning for patients?

Case report: Clinical workflow considerations for treating soft-tissue sarcoma on a 1.5-T MR-Linac

We present specific issues that arose when using a 1.5-Tesla MR-Linac to treat a series of 4 soft-tissue sarcoma (STS) patients. These issues arose from the combination of typical STS attributes (long, off-axis target) and MR-Linac design-specific limitations on field size and patient positioning. Despite the availability of on-line plan adaptation, STS patients were more efficiently treated after workflow changes to improve patient selection and immobilization. Other issues arising from off-axis STS target locations: geometric distortion of MR images and patient-specific QA, are discussed.

Clinician's primer for soft tissue sarcomas: Nuances of histologic subtypes

Soft tissue sarcomas are a rare group of mesenchymal malignancies, with greater than 100 histologic subtypes. Advancements in understanding these subtypes has enabled histology-tailored management. This primer describes the workup and management of generalized soft tissue sarcomas of the extremity, trunk, and retroperitoneum while also highlighting the unique attributes of many subtypes. The subtypes chosen for review include those that are most common as well as those demonstrating unique behaviors or targets for management. The focus is on initial management of localized disease; however, for situations in which novel systemic agents have been discovered, the treatment of metastatic disease is discussed. This report is a reference to be used in addition to other comprehensive reviews, such as guidelines from the National Comprehensive Cancer Network, the European Society for Medical Oncology, and the American Society for Radiation Oncology. It is not a substitute for referral to an expert sarcoma center for critical pathology review and management by an experienced team. Importantly, patients who are treated at expert sarcoma centers have better outcomes than those who are not.

The Impact of Perioperative Radiotherapy on Disease-Specific Survival in Patients with Localized Retroperitoneal Liposarcoma: A Population-Based Propensity-Score Matched Analysis

BACKGROUND

The impact of radiotherapy on the oncologic outcome of retroperitoneal liposarcoma (RPLS) remains controversial. The aim of this study was to evaluate the effect of radiotherapy on disease-specific survival (DSS) in a cohort of patients with RPLSs.

METHODS

In this population-based, retrospective cohort study, patients with localized RPLSs who underwent surgical therapy were identified from the Surveillance, Epidemiology, and End Results-17 cancer registry program. After propensity-score matching for potential confounders, multivariable logistic and Cox regression analyses were used to examine factors associated with DSS and radiotherapy.

RESULTS

From 2004 to 2020, 1692 patients with localized RPLS who underwent surgical therapy were identified (84.2%  White, 44.6% female, mean age 62 years). Of those patients, 393 patients (23.2%) received perioperative radiotherapy. Patients who received radiotherapy had a higher rate of tumor size between 10 and 20 cm and unknown tumor grading. After propensity-score matching, multivariable adjusted Cox regression and Kaplan-Meier survival analysis demonstrated no improvement of DSS for patients who underwent radiotherapy (hazard ratio 1.04, confidence interval 0.81-1.32; log-rank p = 0.47). Patient age ≥80 years, larger tumor size, and tumor grading G3 versus G1/2 were associated with an increased risk of death due to RPLS. Subgroup analyses stratified by grading showed similar outcomes.

CONCLUSIONS

The administration of perioperative radiotherapy did not improve DSS in patients undergoing surgery for localized RPLS in this population-based study. Therefore, the use of perioperative radiotherapy in these patients may be questioned. However, the findings should be interpreted with caution due to the inherent limitations of the Surveillance, Epidemiology, and End Results (SEER) database.

Pandemic driven preoperative moderate hypofractionated radiotherapy for soft tissue sarcomas

PURPOSE

Moderate hypofractionation was adopted to reduce hospital visits during the COVID-19 pandemic aiming to maintain treatment efficacy for soft tissue sarcoma (STS) patients, shifting preoperative schedules from 25 fractions of 2 Gy to 14-15 fractions of 3 Gy. This study evaluates the clinical implications and outcomes of this schedule, focusing on wound complications, radiation toxicity, local tumour control, and distant metastases.

PATIENTS AND METHODS

Data was collected from patients treated between 01 and 01-2020 and 31-12-2023. Outcomes included wound complications within 120 days post-surgery, local-recurrence, distant metastases and radiation toxicity. Logistic regression was performed to identify factors associated with wound complications. The cumulative incidence of local recurrence and distant metastases were estimated with a competing risk model.

RESULTS

Sixty-six patients were analysed, with a mean age of 74 years (standard deviation (SD)± 11). Tumours were mainly localized in the lower extremities (64 %), mean size 103 mm (SD±58). Median follow-up was 29 months (range 2-50). A R0 resection margin was achieved in 77 % of the operated patients. The wound complication rate was 33 %, with moderate complications in 13 patients and severe in 6. The cumulative incidences of local recurrence and distant metastases at 2 years were 7.6 % (standard error (SE) 3.7 %) and 29 % (SE 6 %, Fig. 1) respectively. Acute grade 3 dermatitis occurred in one patient (1.5 %)and two patients experienced late grade 3 toxicity (fractures, 3.0 %). Twenty patients developed distant metastases, two diagnosed before start of the treatment. Eighteen patients died, with six deaths from distant metastases and one from the primary tumour.

CONCLUSION

Preoperative moderate hypofractionation for STS during COVID-19 showed promising results, with no increase in postoperative wound complications and favourable local failure rates.

Principles of Surgical Treatment of Soft Tissue Sarcomas

Soft tissue sarcoma (STS) is a group of highly heterogeneous tumors of mesenchymal origin that have variable primary site locations and clinical behavior. Despite the broad diversity of STS, the standard of care involves surgical resection with or without radiation therapy (RT) to control local recurrence and systemic treatment in select cases. The complexities of STS require a critical understanding of the preoperative work-up process, surgical treatment, and postoperative management. Advanced imaging plays a vital role in the characterization of the soft tissue mass, preoperative biopsy planning, and disease staging. Surgical treatment prioritizes wide resection with negative margins, supported by newer margin classification systems for better prognosis. Further, advancements in surgical technique have enabled limb-salvage surgery to largely replace amputation in the management of these tumors. Additional surgical considerations, such as nerve preservation, vascular reconstruction, and complex tissue closure, further highlight the complexity of STS management. Lastly, postoperative follow-up is critical for the early detection of local or distant recurrences. For complex cases, such as unplanned excisions or invasive tumors, strategies like re-resection may be beneficial. Ongoing research into imaging, chemotherapy, and targeted therapies will further refine management strategies, especially in complex and recurrent cases. This review highlights the essential aspects of STS surgical management and underscores the need for coordinated, multidisciplinary care to enhance both survival and quality of life for affected patients.

Identification and validation of soft tissue sarcoma-specific transcriptomic model for predicting radioresistance

PURPOSE

We aimed to identify the transcriptomic signatures of soft tissue sarcoma (STS) related to radioresistance and establish a model to predict radioresistance.

MATERIALS AND METHODS

Nine STS cell lines were cultured. Adenosine triphosphate-based viability was determined 5 days after irradiation with 8 Gy of X-rays in a single fraction. Radiosensitive and radioresistant groups were stratified according to the survival rates. Whole transcriptomic sequencing analysis was performed and differentially expressed genes (DEGs) were identified between the radiosensitive and radioresistant groups. For model generation, a cohort of 59 patients with sarcomas from The Cancer Genome Atlas (TCGA) was used. DEGs of the responder and non-responder groups according to the radiotherapy-best response were identified. The overlapping DEGs between those from TCGA data and the STS cell line were subjected to linear regression to develop a formula, namely the STS-specific radioresistance index (STS-RRI), and its performance was compared with that of the previously established radiosensitivity index (RSI).

RESULTS

We selected thirteen overlapping DEGs and established STS-RRI using seven of them: STS-RRI = 1.5185 × MYO16-0.01575 × MYH11 + 3.900375 × KCTD16 + 0.105375 × SYNPO2-0.777375 × MYPN-0.849875 × PCSK6-0.700125 × LTK + 39.4635. Delong's test revealed that the STS-RRI performed better at stratifying responder and non-responder in TCGA cohort than the RSI (p = .002). The progression-free survival curves of the TCGA cohort were significantly discriminated by STS-RRI (p = .013) but not by RSI (p = .241).

CONCLUSION

We developed the STS-RRI to predict the radioresistance of patients with STS in the TCGA dataset, showing a higher performance than RSI.

The sarcoma ring trial: a case-based analysis of inter-center agreement across 21 German-speaking sarcoma centers

PURPOSE

The management of soft tissue sarcoma (STS) at reference centers with specialized multidisciplinary tumor boards (MTB) improves patient survival. The German Cancer Society (DKG) certifies sarcoma centers in German-speaking countries, promoting high standards of care. This study investigated the variability in treatment recommendations for localized STS across different German-speaking tertiary sarcoma centers.

METHODS

In this cross-sectional case-based survey study, 5 anonymized patient cases with imaging data of localized STS were presented to MTBs of 21 German-speaking tertiary referral hospitals. Centers provided recommendations on treatment sequence and modalities, along with the consensus level within their MTB. Agreement percentages were calculated, and consensus levels were rated on a scale of 1 to 10.

RESULTS

Five patient cases were discussed resulting in 105 recommendations. Agreement percentages for case 1 to 5 were 14.3%, 61.9%, 33.3%, 52.4% and 9.3%, with a median agreement percentage of 33.3%. Grouping pre- and postoperative therapies as "perioperative" and including recommendations with and without regional hyperthermia raised the median agreement to 47.6%. The mean consensus level within each center across all 5 cases was 9.5.

CONCLUSION

This first case-based analysis of inter-center agreement for STS management in German-speaking countries reveals low inter-center agreement but high intra-center consensus. Our study includes nearly all tertiary sarcoma centers in German-speaking countries, affirming its strong external validity. These findings suggest potential and clinically very relevant differences in treatment standards among sarcoma centers. Enhanced case-based exchanges and collaborative efforts are needed to reduce discrepancies and standardize the management of STS patients.

Hypofractionated accelerated radiation dose-painting (HARD) improves outcomes in unresected soft-tissue sarcoma

Soft tissue sarcomas (STS) are radioresistant with a low α/β, which may have a biologic benefit with hypofractionation. For unresectable STS, the dose escalation required to achieve durable control is often limited by long-term toxicity risk. We sought to compare an isotoxic approach utilizing hypofractionated accelerated radiation dose-painting (HARD) versus standard fractionated radiation therapy (SFT) in patients with unresected STS. We conducted a retrospective analysis of patients with unresected STS who received either HARD (n = 49) or SFT (n = 43) with photon-based therapy between 1990 and 2022. The 2 HARD regimens each use 3 dose levels based on risk of disease burden. The gross disease, intermediate risk, and low-risk clinical target volumes were treated with either 20-22 fractions of 3/2.5/2-2.2 Gy or 28 fractions of 2.5/2.2/1.8 Gy. SFT included patients treated with definitive intent, receiving ≥ 50 Gy in 1.8-2 Gy per fraction. Clinical endpoints included 3-year local control (LC), overall survival (OS), and progression-free survival (PFS), along with treatment-related toxicity. With a median age of 67 and tumor size of 7 cm, most patients were stage IV (37 %), grade 3 (67 %), had no concurrent systemic therapy (70 %), and were lower extremity tumors (24 %). HARD cohort consisted of higher age, stage, recurrent disease, and median BED4 (p < 0.05), when compared to SFT. With a median follow-up of 35.9 months, HARD demonstrated significant improvement in 3-year LC (96.4 % vs. 48.4 %, p < 0.001), compared to SFT overall, with a median PFS benefit (16 vs. 10 months, p = 0.037) for non-distantly metastatic patients at baseline. On multivariate analysis, HARD was significantly associated with improved LC (HR 0.058, 95 % CI 0.005-0.682, p = 0.024). The HARD regimen found no significant increase in toxicity, with limited acute grade 3 (24 %, all dermatitis) and late grade 3 toxicity (6 %) observed, with no grade 4 or 5 events. HARD regimen significantly improves LC for unresectable STS without a significant increase in toxicity, when compared to a standard fractionated approach, supporting further prospective investigation of this treatment approach.

Hypofractionated Preoperative Radiation Therapy for Soft Tissue Sarcoma: A Systematic Review

PURPOSE

Hypofractionated radiation therapy is being used more frequently for many common cancer sites. Conventionally fractionated radiation therapy treatment regimens have remained the standard of care when radiation therapy is indicated for soft tissue sarcoma (STS). The aim of this study was to systematically review published data on the use of preoperative hypofractionated radiation therapy as part of a curative treatment paradigm in patients with STS. Herein, we summarize current evidence for the use of hypofractionated radiation therapy in the preoperative treatment of STS.

METHODS AND MATERIALS

We conducted a database search for prospectively or retrospectively collected data on patients with a diagnosis of STS treated with hypofractionated radiation therapy. Studies evaluating STS of all histologic subtypes affecting extremities or trunks were included in the search. Articles were screened by 2 independent reviewers for inclusion in this review. Patient, treatment, toxicity, and outcome data were recorded and collated from selected studies.

RESULTS

Twenty-five articles are included in this review. Nine prospective trials have been published since 2020. Dose fractionations range from 25 to 40 Gy in 5 fractions or 28-42.75 Gy in 8-15 fractions. Local control and overall survival outcomes are consistent with historical data for conventionally fractionated radiation therapy. Acute toxicity and wound complication rates are in keeping with acceptable results. Late toxicity data are limited and require longer follow-up. Rates of pathologic complete response are promising across all studies.

CONCLUSIONS

There is a growing body of evidence supporting hypofractionation as safe and effective in the preoperative treatment of STS. This review highlights potential areas that could be further investigated to optimize preoperative treatment for STS.

Outcome of Soft Tissue Popliteal Sarcomas: 15 Years of Experience

Background

Soft-tissue sarcoma involving the popliteal fossa remains challenging because it is difficult to achieve wide margins with limb salvage in this location. Adjuvant therapy is frequently necessary, and limb function can be adversely affected. We reviewed our experience with these tumors. A variety of lesions can be identified within the posterior knee, ranging from simple Baker's cysts to malignant lesions. We present a review of frequently encountered and less common entities using an anatomic sieve, with the aim of providing a diagnostic approach to popliteal fossa masses Soft-tissue sarcomas (STSs) arising from the popliteal fossa present a challenge with regard to local control of primary tumors.

Method

In the study, patients who were operated for a mass in the popliteal region between 2007 and 2018 in our clinic were retrospectively analyzed. Patients were categorized by parameters such as age, gender, extremity direction, type of surgery, AJCC scores, surgical margin, tumor size, presence of distant metastases, mass pathology, follow-up time and MSTS score.

Results

Our study included 13 patients (eight women and five men). The mean age was 48 (range 12-84) years. The mass was located in the left knee in nine patients and the right knee in four patients. Frequent histologic diagnoses were for maliğn soft-tissue tumor liposarcoma (n= 5), synovial sarcoma (n= 3) and pleomorphic sarcoma (n= 2), rabdomyorsarcoma, clear cell sarcoma, peripheral nerve sheath tumor (n=1). Tumor size varied from 3 to 14 cm (median 7 cm). American Joint Committee on Cancer staging was as follows: three patients had stage IIA disease, five patients had stage IIB disease, two patients had stage III and stage IB and 1 patient had stage IV disease. The mean duration of follow-up was 39 (range 12-96) months. All patients underwent wide resection. Recurrence developed in four of these patients during the 5-year follow-up period. Recurrence resection was performed in three of the patients who developed recurrence, while recurrence resection + femur distal tumor resection arthroplasty was performed in one patient. In addition, 3 of these 13 patients received neoadjuvant chemotherapy, while 5 received adjuvant chemotherapy treatment. Neoadjuvant RT was applied to 4 patients with a mass greater than 9 cm. Margins were negative in seven of 13 patients and microscopically positive in five patients. Complications included wound infections in four patients and thrombophlebitis in two patients and one patients peroneal nerve nöropraxy. Of the patients undergoing limb-salvaging procedures, two experienced local recurrences after limb salvage and four experienced lung metastases. Local recurrence was always associated with positive margins. The mean MusculoskeletalTumor Society 1987 score was 50 ( range 35-68). At latest follow-up, six patients had died of disease, one was alive with disease, and five patients remained free of disease.

Conclusion

The popliteal region is a rare area in terms of mass localizations. Inpatients presenting with knee pain, regardless of external findings such as swelling ornot, tumors located in the popliteal region should be considered in patients withoutpathology on direct radiography.

Moderately hypofractionated, preoperative radiotherapy in patients with soft tissue sarcomas (HYPORT-STS): Updated local control, late toxicities, and patient-reported outcomes

BACKGROUND

Moderately hypofractionated, preoperative radiotherapy in patients with soft tissue sarcomas (HYPORT-STS; ClinicalTrials.gov identifier NCT03819985) investigated a radiobiologically equivalent, moderately hypofractionated course of preoperative radiotherapy (RT) 15 × 2.85 Gy in patients with soft tissue sarcoma (STS). Here, the authors report longer term follow-up to update local control and report late toxicities, as well as functional and patient-reported outcomes.

METHODS

HYPORT-STS was a single-center, open-label, single-arm, prospective phase 2 clinical trial that enrolled 120 eligible adult patients with localized STS of the extremities or superficial trunk between 2018 and 2021. Patients received a 3-week course of preoperative RT followed by surgery 4-8 weeks later. End points and follow-up were analyzed from the date of surgery.

RESULTS

The median follow-up was 43 months (interquartile range, 37-52 months), and the 4-year local recurrence-free survival rate was 93%. Overall RT-related late toxicities improved with time from local therapy (p < .001), and few patients had grade ≥2 toxicities (9%; n = 8 of 88) at 2 years. These included: 2% grade ≥2 skin toxicity, 2% fibrosis, 3% lymphedema, and 1% joint stiffness. Four patients (3%) had bone fractures. Both functional outcomes, as measured by the Musculoskeletal Tumor Society Rating Scale (p < .001), and quality of life, as measured by the Functional Assessment of Cancer Therapy-General (p < .001), improved with time from treatment, and both measures were better in follow-up at 2 years compared with baseline.

CONCLUSIONS

Long-term follow up suggests that moderately hypofractionated preoperative RT for patients with STS is safe and effective. Higher grade late toxicities affect a minority of patients. Late toxicities decrease over time, whereas functional outcomes and health-related quality of life seem to improve with more time from combined modality treatment.

Hypofractionated Preoperative Radiation Should Not Yet Be Used as Standard of Care for Extremity and Truncal Soft Tissue Sarcoma

Hypofractionated radiation therapy regimens should not be used as standard of care for localized soft tissue sarcoma.

Diagnosis and management of dedifferentiated liposarcoma: A multidisciplinary position statement

Dedifferentiated liposarcoma (DDLPS) is a malignant mesenchymal neoplasm in desperate need of novel therapeutic approaches. Often occurring in conjunction with well-differentiated liposarcoma (WDLPS), DDLPS can behave more aggressively and exhibits a significant risk for developing recurrence or metastatic disease when compared to its well-differentiated counterpart. A multidisciplinary approach is critically important, particularly for patients with localized disease, as disease presentations are often complex, and the management of patients has become increasingly nuanced as treatment approaches have become more refined. Expert pathology review and appropriate application of diagnostic molecular techniques are key components of DDLPS diagnosis and also reflect an improved understanding of the underlying pathogenesis of the disease. Systemic therapies remain limited for DDLPS, but novel therapies targeting important underlying molecular drivers have resulted in ongoing clinical trials aiming to improve outcomes for patients with advanced disease. In recognition of the increased activity and interest within the DDLPS field, a multidisciplinary group of nationally recognized experts in medical oncology, surgical oncology, radiation oncology, and pathology was convened to summarize key insights. This position paper highlights important points from the meeting and provides evidence-based recommendations for practicing clinicians.

Proton Therapy for Spinal Tumors: A Consensus Statement From the Particle Therapy Cooperative Group

PURPOSE

Proton beam therapy (PBT) plays an important role in the management of primary spine tumors. The purpose of this consensus statement was to summarize safe and optimal delivery of PBT for spinal tumors.

METHODS AND MATERIALS

The Particle Therapy Cooperative Group Skull Base/Central nervous system/Sarcoma Subcommittee consisting of radiation oncologists and medical physicists with specific expertise in spinal irradiation developed expert recommendations discussing treatment planning considerations and current approaches in the treatment of primary spinal tumors.

RESULTS

Computed tomography simulation: factors that require significant consideration include (1) patient comfort, (2) setup reproducibility and stability, and (3) accessibility of appropriate beam angles.

SPINE STABILIZATION HARDWARE

If present, hardware should be placed with cross-links well above/below the level of the primary tumor to reduce the metal burden at the level of the tumor bed. New materials that can reduce uncertainties include polyether-ether-ketone and composite polyether-ether-ketone-carbon fiber implants.

FIELD ARRANGEMENT

Appropriate beam selection is required to ensure robust target coverage and organ at risk sparing. Commonly, 2 to 4 treatment fields, typically from posterior and/or posterior-oblique directions, are used.

TREATMENT PLANNING METHODOLOGY

Robust optimization is recommended for all pencil beam scanning plans (the preferred treatment modality) and should consider setup uncertainty (between 3 and 7 mm) and range uncertainty (3%-3.5%). In the presence of metal hardware, use of an increased range uncertainty up to 5% is recommended.

CONCLUSIONS

The Particle Therapy Cooperative Group Skull Base/Central nervous system/Sarcoma Subcommittee has developed recommendations to enable centers to deliver PBT safely and effectively for the management of primary spinal tumors.

Definitive particle therapy using protons or carbon ions for dedifferentiated liposarcoma

Background

Particle therapy is effective for the treatment of soft tissue sarcomas. However, the clinical outcomes of definitive particle therapy, particularly for dedifferentiated liposarcoma (DDLS), remain unknown.

Purpose

To analyze the treatment outcomes of proton and carbon ion particle therapies for DDLS.

Methods

We retrospectively included patients with DDLS who were treated with particle therapy between 2008 and 2022. The local control (LC), progression-free survival (PFS), and overall survival (OS) rates were evaluated.

Results

Fifty-seven patients were included in this analysis. The median patient age was 68 years (range, 36-91 years). The most common tumor site was the retroperitoneum (n = 37), with a median gross tumor volume (GTV) of 181 cm3. Twenty-nine patients received proton therapy, and 28 patients received carbon ion therapy. The most common fractionation dose was 70.4 Gy (relative biological effectiveness) in 32 fractions (72.7 Gy equivalent dose in 2 Gy fractions [EQD2]). The median follow-up time was 33 months (range, 1-128 months). The 3-year LC, PFS, and OS rates were 73.1 %, 44.6 %, and 70.6 %, respectively. Patients who received a higher prescribed dose (≥72.7 Gy EQD2) showed significantly better LC (p = 0.04) than did those who received a lower prescribed dose. Moreover, those with a larger GTV (≥181 cm3) had significantly worse OS (p = 0.04) than did those with a smaller GTV. Late adverse events occurred in five (9 %) patients.

Conclusions

Particle therapy using protons or carbon ions for the treatment of DDLS is safe and provides good OS and LC. However, further studies with longer follow-up periods and larger cohorts are warranted.

Comparison of Pathologic Tumor Necrosis of Conventional Versus Ultrahypofractionated Preoperative Radiation Therapy in Localized Extremity Soft Tissue Sarcoma and Its Correlation With Clinical Outcomes

PURPOSE

We aimed to determine if ultrahypofractionated radiation therapy (UHYPO-RT) delivering 6 Gy x 5 fractions yields similar tumor necrosis compared with conventional radiation therapy (CONV-RT) with 2 Gy x 25 fractions in soft tissue sarcoma. The clinical significance of tumor necrosis on loco-regional recurrence-free survival (LRFS), distant disease-free survival (DDFS), and overall survival (OS) were assessed.

METHODS AND MATERIALS

Patients with localized soft tissue sarcoma treated with CONV-RT or UHYPO-RT followed by surgery were included. Good response was defined as tumor necrosis ≥90%, and poor response as <90%. The Mann-Whitney U test compared median tumor necrosis. χ2 analysis was used for categorical variables. The Kaplan-Meier function estimated LRFS, DDFS, and OS.

RESULTS

A total of 64 patients received CONV-RT, and 45 received UHYPO-RT. The median tumor size was 7.0 cm, with the lower extremity being the most common site (55%). Myxofibrosarcoma (39%) and undifferentiated pleomorphic sarcoma (16%) were the most frequent histologies. The median time from radiation therapy to surgery was 35 days. There was a significant difference in median tumor necrosis between CONV-RT and UHYPO-RT, with rates of 40% and 60%, respectively (P = .022). Patients receiving UHYPO-RT had a higher percentage of tumor necrosis at the 90% cutoff, achieving 27% compared with 6% for CONV-RT (P = .003). At a median follow-up of 32 months, 12 patients (9%) experienced loco-regional recurrence, 24 patients (19%) faced distant failure, and 19 patients (15%) died of metastatic disease. Patients with <90% necrosis had higher rates of loco-regional (13% vs 0%, P = .207) and distant failure (25% vs 0%, P = .021). Three-year LRFS was 86% for <90% necrosis and 100% for ≥90% necrosis (P = .160). DDFS was 75% for <90% necrosis versus 100% for ≥90% (P = .036). OS rates were 79% and 93%, respectively (P = .290).

CONCLUSIONS

Preoperative RT with UHYPO-RT was associated with a higher rate of tumor necrosis ≥90% than CONV-RT. Our data suggest that more extensive necrosis is associated with better clinical outcomes.

Neo-adjuvant radiation and intratumoral immunotherapy followed by surgery-NARIS trial for extremity soft tissue sarcoma

Extremity soft tissue sarcoma (ESTS) is a rare malignant nonepithelial disease, calling for combined modality treatments with surgery to further improve local control rates and long-term survival, especially in patients with multiple local recurrences with or without risk of amputation. In this double-arm, open-label, Phase II clinical trial, we will enroll 30 patients with pathologically confirmed ESTS without nodal involvement or distant metastases. Patients are randomly assigned to the combination treatment group or the radiation monotherapy group. Additionally, tumor and biological samples will be obtained directly before and after neoadjuvant therapy, allowing for studies of immune response and primary drug resistance mechanisms.Clinical Trial Registration: ChiCTR2200060659 (http://www.chictr.org.cn) (ClinicalTrials.gov).

Novel MRI scoring system to assess osseous malignancy in soft tissue sarcoma patients following radiotherapy

PURPOSE

Radiation induced changes in bone such as radiation osteitis are commonly identified on magnetic resonance imaging (MRI) in patients who receive radiotherapy for soft tissue sarcoma (STS) management. This study proposes a novel MRI scoring system to assess osseous lesions and predict potential for malignancy based on MRI score in STS patients who received radiotherapy.

METHODS

The MRI score consisted of 3 parameters: morphology, signal intensity, and progression. Interobserver reliability between MRI scores were analyzed with Cohen's kappa coefficient. Receiver operating curve (ROC) analysis was performed to determine a predictive MRI score for malignancy.

RESULTS

156 MRI's from 30 STS patients who received radiotherapy were retrospectively reviewed. Two (6.7 %) patients developed regional osseous metastasis identified on MRI. The kappa coefficient of the scoring system was 0.785 demonstrating substantial interobserver agreement (p < 0.001). ROC analysis demonstrated that the optimal cut-off value for malignant lesion on MRI was 5.5 (area under the curve 0.998; p < 0.001).

CONCLUSIONS

This novel MRI scoring system recommends lesions with a score of six and above to be biopsied to distinguish if malignancy is present. We believe this scoring system can be utilized by multidisciplinary care teams to guide clinical recommendations for patients with STS and MRI findings concerning for malignancy versus radiation induced changes.

Progress in histology specific treatments in soft tissue sarcoma

INTRODUCTION

Soft tissue sarcomas (STS) represent a heterogenous group of rare tumors, primarily treated with surgery. Preoperative radiotherapy is often recommended for extremity high-risk STS. Neoadjuvant chemotherapy, typically based on doxorubicin with ifosfamide, has shown efficacy in limbs and trunk wall STS. Second-line chemotherapy, commonly utilized in the metastatic setting, is mostly histology-driven. Molecular targeted agents are used across various histologies, and although the use of immunotherapy in STS is still in its early stages, there is increasing interest in exploring its potential.

AREAS COVERED

This article involved an extensive recent search on PubMed. It explored the current treatment landscape for localized and metastatic STS, focusing on the combined use of radiotherapy and chemotherapy for both extremity and retroperitoneal tumors, and with a particular emphasis on the most innovative histopathology driven therapeutic approaches. Additionally, ongoing clinical trials identified via clinicaltrials.gov are included.

EXPERT OPINION

Recently there have been advancements in the treatment of STS, largely driven by the outcomes of clinical trials. However further research is imperative to comprehend the effect of chemotherapy, targeted therapy and immunotherapy in various STS, as well as to identify biomarkers able to predict which patients are most likely to benefit from these treatments.

Outcomes for Patients With Head and Neck Sarcoma Treated Curatively With Radiation Therapy and Surgery

PURPOSE

Soft tissue sarcomas (STSs) of the head and neck (H&N) are rare malignancies that are challenging to manage. We sought to describe the outcomes of patients treated with curative intent using combined surgery and radiation therapy (RT) for H&N STS.

METHODS AND MATERIALS

We performed a single-institution retrospective review of patients with nonmetastatic STS of the H&N who were treated from 1968 to 2020. The Kaplan-Meier method was used to estimate disease-specific survival (DSS) and local control (LC). Multivariable analyses (MVAs) were conducted using Cox proportional hazards model.

RESULTS

One hundred ninety-two patients had a median follow-up of 82 months. Tumors arose in the neck (n = 50, 26%), paranasal sinuses (n = 36, 19%), or face (n = 23, 12%). Most patients were treated with postoperative RT (n = 134, 70%). Postoperative RT doses were higher (median, 60 Gy; preoperative dose, 50 Gy; P < .001). Treatment sequence was not associated with LC (preoperative RT, 78% [63%-88%]; postoperative RT, 75% [66%-82%]; P = .48). On MVA, positive/uncertain margin was the only variable associated with LC (hazard ratio [HR], 2.54; 95% CI, 1.34-4.82; P = .004). LC was significant on MVA (HR, 4.48; 95% CI, 2.62-7.67; P < .001) for DSS. Patients who received postoperative RT were less likely to experience a major wound complication (7.5% vs 22.4%; HR, 0.28; 95% CI, 0.11-0.68; P = .005). There was no difference in the rate of late toxicities between patients who received preoperative or postoperative RT.

CONCLUSIONS

H&N STS continues to have relatively poorer LC than STS of the trunk or extremities. We found LC to be associated with DSS. Timing of RT did not impact oncologic or long-term toxicity outcomes; however, preoperative RT did increase the chance of developing a major wound complication.

Development and benchmarking of a Deep Learning-based MRI-guided gross tumor segmentation algorithm for Radiomics analyses in extremity soft tissue sarcomas

BACKGROUND

Volume of interest (VOI) segmentation is a crucial step for Radiomics analyses and radiotherapy (RT) treatment planning. Because it can be time-consuming and subject to inter-observer variability, we developed and tested a Deep Learning-based automatic segmentation (DLBAS) algorithm to reproducibly predict the primary gross tumor as VOI for Radiomics analyses in extremity soft tissue sarcomas (STS).

METHODS

A DLBAS algorithm was trained on a cohort of 157 patients and externally tested on an independent cohort of 87 patients using contrast-enhanced MRI. Manual tumor delineations by a radiation oncologist served as ground truths (GTs). A benchmark study with 20 cases from the test cohort compared the DLBAS predictions against manual VOI segmentations of two residents (ERs) and clinical delineations of two radiation oncologists (ROs). The ROs rated DLBAS predictions regarding their direct applicability.

RESULTS

The DLBAS achieved a median dice similarity coefficient (DSC) of 0.88 against the GTs in the entire test cohort (interquartile range (IQR): 0.11) and a median DSC of 0.89 (IQR 0.07) and 0.82 (IQR 0.10) in comparison to ERs and ROs, respectively. Radiomics feature stability was high with a median intraclass correlation coefficient of 0.97, 0.95 and 0.94 for GTs, ERs, and ROs, respectively. DLBAS predictions were deemed clinically suitable by the two ROs in 35% and 20% of cases, respectively.

CONCLUSION

The results demonstrate that the DLBAS algorithm provides reproducible VOI predictions for radiomics feature extraction. Variability remains regarding direct clinical applicability of predictions for RT treatment planning.

Modern Multidisciplinary Management of Soft Tissue Sarcoma of the Extremity and Trunk

Soft tissue sarcomas (STS) of the extremity and trunk are heterogeneous and rare tumors that require coordinated multidisciplinary management. Surgical resection remains the backbone of treatment for localized tumors, with the addition of radiotherapy to surgery to achieve high rates of local control. Despite this, overall survival is limited because of significant distant metastatic risk and a lack of efficacious systemic therapies. Clinical trials have produced conflicting results on the impact of systemic therapy in the neoadjuvant and adjuvant settings for patients with localized disease, leaving systemic treatment decisions largely guided by shared decision making and prognostic prediction tools such as nomograms. This article will review the foundational data as well as latest developments in surgical, radiotherapy, and systemic management supporting current practice guidelines for localized STS of the extremity and trunk.

The role of radiotherapy in multimodal treatment of non-rhabdomyosarcoma soft tissue sarcomas in children: A real life report from a tertiary center

OBJECTIVE

The current treatment of pediatric non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) is a multimodal risk-based approach. Today, smaller fields and lower doses of radiotherapy (RT) have become standard. In this study, it was aimed to evaluate the treatment outcomes and toxicity profile in children with NRSTS that received RT as a part of multimodal therapy.

METHODS

Twenty-nine patients with pediatric NRSTS treated with neoadjuvant or adjuvant RT between 1998 and 2022 were evaluated retrospectively. Kaplan-Meier method was used for survival analyses.

RESULTS

Median follow-up was 36 months (range, 6-291 months). The median neoadjuvant and adjuvant RT doses were 50 Gy (range, 45-66 Gy) and 54 Gy (45-66 Gy), respectively. During follow-up, six (21%) patients developed a local recurrence and 10 (35%) had distant metastasis. The 5-year local control, overall survival (OS), local recurrence-free survival, and distant metastasis-free survival rate was 79%, 67%, 59%, and 61%, respectively. In multivariate analysis, a ≤5-cm tumor, gross tumor resection, Children's Oncology Group (COG) low-risk group, and absence of neoadjuvant chemotherapy were independent favorable prognostic factors for OS. Severe (≥ grade 3) late toxicity was observed in 6 (20%) patients.

CONCLUSIONS

RT is a crucial component in the multimodal risk-based treatment approach for pediatric NRSTS. However, late toxicity rates are still high and should be improved. Patients with a ≤5-cm tumor, COG low-risk group and treated with gross tumor resection have increased survival rates.

What is the Optimal Treatment Strategy after Sarcoma R2 Surgery?

OPINION STATEMENT

Soft tissue sarcomas (STS) are rare tumours of mesenchymal origin, most commonly occurring in the extremity but also in the retroperitoneum. The curative treatment for STS is radical surgery with wide margins, in some cases in combination with perioperative radiotherapy and chemotherapy. Nonradical resection (R2) of STS has been an emerging issue in recent decades, as optimal subsequent management remains debatable. Similarly, there is still no consensus on optimal surgical margins. Combining multiple treatment modalities in adjuvant therapy can achieve local and distant control in patients following surgery with positive margins. Patients who have undergone nonradical resection therefore require additional surgical interventions, and adjuvant radiotherapy resulting in a better prognosis but a higher number of complications. Following non-radical treatment, patients with limb and trunk wall sarcomas and retroperitoneal sarcomas should also undergo increased oncological surveillance. Given the potential issues that may emerge in such clinical situations, it is crucial to up-date the current guidelines to enhance the long-term prognosis of these patients.

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.

A Two-Step Approach to the Surgical Treatment of Soft-Tissue Sarcomas

Background: Nowadays, limb-sparing procedures are the gold standard in the treatment of soft-tissue sarcomas of the limbs. Wide tumor resection with appropriate oncological margins, reconstruction, and stabilization of the involved bone and joint and restoration of the soft tissue lost are essential in order to obtain good clinical and functional outcomes. Tumor excision and soft-tissue reconstruction performed in one-step surgery is chosen by many centers as the preferred approach; however, according to our experience in some selected patients, two-step surgery performed using a dermal regeneration template first and then a margin revision, taking into account the definitive results of the anatomopathological exam conducted over the surgical specimen from the previous surgery, associated with definitive reconstruction surgery over a healthy bed of granulated tissue, showed many potential benefits. Methods: A retrospective observational study was conducted on thirteen patients who underwent a two-step reconstruction procedure using dermal substitution after soft-tissue sarcoma excision. Results: Clinically, the enrolled patients achieved excellent contour and cosmesis of their surgical wounds, with a mean VSS value of 3.07. During the follow-up period, no local recurrences were observed in any patient. Conclusions: Two-step surgery represents the most suitable solution to allow surgical radicality with minimal recurrency and adequate soft-tissue reconstruction, avoiding the possibility of wasting autologous tissue. Our patients generally embraced this approach and the management that followed.

Prospective phase II trial of preoperative hypofractionated proton therapy for extremity and truncal soft tissue sarcoma: the PRONTO study rationale and design

BACKGROUND

Oncologic surgical resection is the standard of care for extremity and truncal soft tissue sarcoma (STS), often accompanied by the addition of pre- or postoperative radiation therapy (RT). Preoperative RT may decrease the risk of joint stiffness and fibrosis at the cost of higher rates of wound complications. Hypofractionated, preoperative RT has been shown to provide acceptable outcomes in prospective trials. Proton beam therapy (PBT) provides the means to decrease dose to surrounding organs at risk, such as the skin, bone, soft tissues, and adjacent joint(s), and has not yet been studied in patients with extremity and truncal sarcoma.

METHODS

Our study titled "PROspective phase II trial of preoperative hypofractionated protoN therapy for extremity and Truncal soft tissue sarcOma (PRONTO)" is a non-randomized, prospective phase II trial evaluating the safety and efficacy of preoperative, hypofractionated PBT for patients with STS of the extremity and trunk planned for surgical resection. Adult patients with Eastern Cooperative Group Performance Status ≤ 2 with resectable extremity and truncal STS will be included, with the aim to accrue 40 patients. Treatment will consist of 30 Gy radiobiological equivalent of PBT in 5 fractions delivered every other day, followed by surgical resection 2-12 weeks later. The primary outcome is rate of major wound complications as defined according to the National Cancer Institute of Canada Sarcoma2 (NCIC-SR2) Multicenter Trial. Secondary objectives include rate of late grade ≥ 2 toxicity, local recurrence-free survival and distant metastasis-free survival at 1- and 2-years, functional outcomes, quality of life, and pathologic response.

DISCUSSION

PRONTO represents the first trial evaluating the use of hypofractionated PBT for STS. We aim to prove the safety and efficacy of this approach and to compare our results to historical outcomes established by previous trials. Given the low number of proton centers and limited availability, the short course of PBT may provide the opportunity to treat patients who would otherwise be limited when treating with daily RT over several weeks. We hope that this trial will lead to increased referral patterns, offer benefits towards patient convenience and clinic workflow efficiency, and provide evidence supporting the use of PBT in this setting.

TRIAL REGISTRATION

NCT05917301 (registered 23/6/2023).

The role of 18F-FDG PET in minimizing variability in gross tumor volume delineation of soft tissue sarcomas

BACKGROUND

Accurate gross tumor volume (GTV) delineation is a critical step in radiation therapy treatment planning. However, it is reader dependent and thus susceptible to intra- and inter-reader variability. GTV delineation of soft tissue sarcoma (STS) often relies on CT and MR images.

PURPOSE

This study investigates the potential role of 18F-FDG PET in reducing intra- and inter-reader variability thereby improving reproducibility of GTV delineation in STS, without incurring additional costs or radiation exposure.

MATERIALS AND METHODS

Three readers performed independent GTV delineation of 61 patients with STS using first CT and MR followed by CT, MR, and 18F-FDG PET images. Each reader performed a total of six delineation trials, three trials per imaging modality group. Dice Similarity Coefficient (DSC) score and Hausdorff distance (HD) were used to assess both intra- and inter-reader variability using generated simultaneous truth and performance level estimation (STAPLE) GTVs as ground truth. Statistical analysis was performed using a Wilcoxon signed-ranked test.

RESULTS

There was a statistically significant decrease in both intra- and inter-reader variability in GTV delineation using CT, MR 18F-FDG PET images vs. CT and MR images. This was translated by an increase in the DSC score and a decrease in the HD for GTVs drawn from CT, MR and 18F-FDG PET images vs. GTVs drawn from CT and MR for all readers and across all three trials.

CONCLUSION

Incorporation of 18F-FDG PET into CT and MR images decreased intra- and inter-reader variability and subsequently increased reproducibility of GTV delineation in STS.

Update on Dosing and Fractionation for Neoadjuvant Radiotherapy for Localized Soft Tissue Sarcoma

OPINION STATEMENT

Neoadjuvant radiotherapy (RT) over 5-6 weeks with daily doses of 1.8-2.0 Gy to a total dose of 50-50.4 Gy is standard of care for localized high-grade soft tissue sarcomas (STS) of the extremities and trunk wall. One exception is myxoid liposarcomas where the phase II DOREMY trial applying a preoperative dose of 36 Gy in 2 Gy fractions (3-4 weeks treatment) has achieved excellent local control rates of 100% after a median follow-up of 25 months.Hypofractionated preoperative RT has been investigated in a number of phase II single-arm studies suggesting that daily doses of 2.75-8 Gy over 1-3 weeks can achieve similar oncological outcomes to conventional neoadjuvant RT. Prospective data with direct head-to-head comparison to conventional neoadjuvant RT investigating oncological outcomes and toxicity profiles is eagerly awaited.For the entire group of retroperitoneal sarcomas, RT is not the standard of care. The randomized multi-center STRASS trial did not find a benefit in abdominal recurrence-free survival by the addition of preoperative RT. However, for the largest histological subgroup of well-differentiated and grades I and II dedifferentiated liposarcomas, the STRASS trial and the post-hoc propensity-matched STREXIT analysis have identified a possible benefit in survival by preoperative RT. These patients deserve to be informed about the pros and cons of preoperative RT while the longer follow-up data from the STRASS trial is awaited.

Neoadjuvant Therapies Do Not Reduce Epidermal Growth Factor Receptor (EGFR) Expression or EGFR-Targeted Fluorescence in a Murine Model of Soft-Tissue Sarcomas

PURPOSE

ABY-029, an epidermal growth factor receptor (EGFR)-targeted, synthetic Affibody peptide labeled with a near-infrared fluorophore, is under investigation for fluorescence-guided surgery of sarcomas. To date, studies using ABY-029 have occurred in tumors naïve to chemotherapy (CTx) and radiation therapy (RTx), although these neoadjuvant therapies are frequently used for sarcoma treatment in humans. The goal of this study was to evaluate the impact of CTx and RTx on tumor EGFR expression and ABY-029 fluorescence of human soft-tissue sarcoma xenografts in a murine model.

PROCEDURES

Immunodeficient mice (n = 98) were divided into five sarcoma xenograft groups and three treatment groups - CTx only, RTx only, and CTx followed by RTx, plus controls. Four hours post-injection of ABY-029, animals were sacrificed followed by immediate fluorescence imaging of ex vivo adipose, muscle, nerve, and tumor tissues. Histological hematoxylin and eosin staining confirmed tumor type, and immunohistochemistry staining determined EGFR, cluster of differentiation 31 (CD31), and smooth muscle actin (SMA) expression levels. Correlation analysis (Pearson's correlation coefficients, r) and linear regression (unstandardized coefficient estimates, B) were used to determine statistical relationships in molecular expression and tissue fluorescence between xenografts and treatment groups.

RESULTS

Neoadjuvant therapies had no broad impact on EGFR expression (|B|≤ 7.0, p ≥ 0.4) or on mean tissue fluorescence (any tissue type, (|B|≤ 2329.0, p ≥ 0.1). Mean tumor fluorescence was significantly related to EGFR expression (r = 0.26, p = 0.01), as expected.

CONCLUSION

Results suggest that ABY-029 as an EGFR-targeted, fluorescent probe is not negatively impacted by neoadjuvant soft-tissue sarcoma therapies, although validation in humans is required.

Novel Definitive Hypofractionated Accelerated Radiation Dose-painting (HARD) for Unresected Soft Tissue Sarcomas

Purpose

Soft tissue sarcomas (STS) are historically radioresistant, with surgery being an integral component of their treatment. With their low α/β, STS may be more responsive to hypofractionated radiation therapy (RT), which is often limited by long-term toxicity risk to surrounding normal tissue. An isotoxic approach using a hypofractionated accelerated radiation dose-painting (HARD) regimen allows for dosing based on clinical risk while sparing adjacent organs at risk.

Methods and Materials

We retrospectively identified patients from 2019 to 2022 with unresected STS who received HARD with dose-painting to high, intermediate, and low-risk regions of 3.0 Gy, 2.5 Gy, and 2.0 to 2.3 Gy, respectively, in 20 to 22 fractions. Clinical endpoints included local control, locoregional control, progression free survival, overall survival, and toxicity outcomes.

Results

Twenty-seven consecutive patients were identified and had a median age of 68 years and tumor size of 7.0 cm (range, 1.2-21.0 cm). Tumors were most often high-grade (70%), stage IV (70%), located in the extremities (59%), and locally recurrent (52%). With a median follow-up of 33.4 months, there was a 3-year locoregional control rate of 100%. The 3-year overall and progression-free survival were 44.9% and 23.3%, respectively. There were 5 (19%) acute and 2 (7%) late grade 3 toxicities, and there were no grade 4 or 5 toxicities at any point.

Conclusions

The HARD regimen is a safe method of dose-escalating STS, with durable 3-year locoregional control. This approach is a promising alternative for unresected STS, though further follow-up is required to determine long-term control and toxicity.

Are We Ready for Life in the Fast Lane? A Critical Review of Preoperative Hypofractionated Radiotherapy for Localized Soft Tissue Sarcoma

This critical review aims to summarize the relevant published data regarding hypofractionation regimens for preoperative radiation therapy (RT) prior to surgery for soft tissue sarcoma (STS) of the extremity or superficial trunk. We identified peer-reviewed publications using a PubMed search on the MeSH headings of "soft tissue sarcoma" AND "hypofractionated radiation therapy." To obtain complication data on similar anatomical radiotherapeutic scenarios we also searched "hypofractionated radiation therapy" AND "melanoma" as well as "hypofractionated radiation therapy" AND "breast cancer." We then used reference lists from relevant articles to obtain additional pertinent publications. We also incorporated relevant abstracts presented at international sarcoma meetings and relevant clinical trials as listed on the ClinicalTrials.gov website. Detailed data are presented and contextualized for ultra-hypofractionated and moderately hypofractionated regimens with respect to local control, wound complications, and amputation rates. Comparative data are also presented for late toxicities including: fibrosis, joint limitation, edema, skin integrity, and bone fracture or necrosis. These data are compared to a standard regimen of 50 Gy in 25 daily fractions delivered over 5 weeks. This analysis supports the continued use of a standard regimen for preoperative RT for STS of 25 × 2 Gy over 5 weeks without concurrent chemotherapy. Use of concurrent chemotherapy with preoperative RT for STS should be reserved for well-designed clinical trials. A randomized trial of ultra-hypofractionated and moderately hypofractionated pre op RT for STS is warranted, but it is critical for the primary endpoint (or co-primary endpoint) to be late toxicity to: bone, soft tissue, joint, and skin.

Sacral-Nerve-Sparing Planning Strategy in Pelvic Sarcomas/Chordomas Treated with Carbon-Ion Radiotherapy

To minimize radiation-induced lumbosacral neuropathy (RILSN), we employed sacral-nerve-sparing optimized carbon-ion therapy strategy (SNSo-CIRT) in treating 35 patients with pelvic sarcomas/chordomas. Plans were optimized using Local Effect Model-I (LEM-I), prescribed DRBE|LEM-I|D50% (median dose to HD-PTV) = 73.6 (70.4-76.8) Gy (RBE)/16 fractions. Sacral nerves were contoured between L5-S3 levels. DRBE|LEM-I to 5% of sacral nerves-to-spare (outside HD-CTV) (DRBE|LEM-I|D5%) were restricted to <69 Gy (RBE). The median follow-up was 25 months (range of 2-53). Three patients (9%) developed late RILSN (≥G3) after an average period of 8 months post-CIRT. The RILSN-free survival at 2 years was 91% (CI, 81-100). With SNSo-CIRT, DRBE|LEM-I|D5% for sacral nerves-to-spare = 66.9 ± 1.9 Gy (RBE), maintaining DRBE|LEM-I to 98% of HD-CTV (DRBE|LEM-I|D98%) = 70 ± 3.6 Gy (RBE). Two-year OS and LC were 100% and 93% (CI, 84-100), respectively. LETd and DRBE with modified-microdosimetric kinetic model (mMKM) were recomputed retrospectively. DRBE|LEM-I and DRBE|mMKM were similar, but DRBE-filtered-LETd was higher in sacral nerves-to-spare in patients with RILSN than those without. At DRBE|LEM-I cutoff = 64 Gy (RBE), 2-year RILSN-free survival was 100% in patients with <12% of sacral nerves-to-spare voxels receiving LETd > 55 keV/µm than 75% (CI, 54-100) in those with ≥12% of voxels (p < 0.05). DRBE-filtered-LETd holds promise for the SNSo-CIRT strategy but requires longer follow-up for validation.

Novel Postoperative Hypofractionated Accelerated Radiation Dose-Painting Approach for Soft Tissue Sarcoma

Purpose

Hypofractionated radiation therapy (RT) offers benefits in the treatment of soft tissue sarcomas (STS), including exploitation of the lower α/β, patient convenience, and cost. This study evaluates the acute toxicity of a hypofractionated accelerated RT dose-painting (HARD) approach for postoperative treatment of STS.

Methods and Materials

This is a retrospective review of 53 consecutive patients with STS who underwent resection followed by postoperative RT. Standard postoperative RT dosing for R0/R1/gross disease with sequential boost (50 Gy + 14/16/20 Gy in 32-35 fractions) were replaced with dose-painting, which adapts dose based on risk of disease burden, to 50.4 and 63, 64.4, 70 Gy in 28 fractions, respectively. The first 10 patients were replanned with a sequential boost RT approach and dosimetric indices were compared. Time-to-event outcomes, including local control, regional control, distant control, and overall survival, were estimated with Kaplan-Meier analysis.

Results

Median follow-up was 25.2 months. Most patients had high-grade (59%) STS of the extremity (63%) who underwent resection with either R1 (40%) or close (36%) margins. Four patients experienced grade 3 acute dermatitis which resolved by the 3-month follow-up visit. The 2-year local control, regional control, distant control, and overall survival were 100%, 92%, 68%, and 86%, respectively. Compared with the sequential boost plan, HARD had a significantly lower field size (total V50 Gy; P = .002), bone V50 (P = .031), and maximum skin dose (P = .008). Overall treatment time was decreased by 4 to 7 fractions, which translated to a decrease in estimated average treatment cost of $3056 (range, $2651-$4335; P < .001).

Conclusions

In addition to benefits in cost, convenience, and improved biologic effect in STS, HARD regimen offers a safe treatment approach with dosimetric advantages compared with conventional sequential boost, which may translate to improved long-term toxicity.

Patterns of Local Recurrence and Risk of Skin Recurrence in Soft Tissue Sarcomas After Surgical Resection

PURPOSE

Although there is a theoretical risk of skin seeding during surgical resection of soft tissue sarcomas (STSs), current consensus guidelines recommend against routine use of bolus during radiation therapy (RT). However, the risk of skin recurrence has not been systematically assessed. We aimed to assess the patterns of local recurrence (LR) in patients with STS treated with surgery with or without RT.

METHODS AND MATERIALS

We performed a retrospective analysis of adults with STSs evaluated at our institution between 2007 and 2021. For patients who developed LR, the depth was evaluated. Progression-free survival and overall survival were analyzed from time of first LR using the Kaplan-Meier method. Cumulative incidence of distant metastasis was calculated with competing risk analysis from date of LR.

RESULTS

Of the 206 patients evaluated, 20 had LR (9.7%). Among patients with LR, 5 patients (25.0%) were treated with surgery alone and 15 patients (75.0%) with surgery and RT. In patients treated with RT, 46.7% had preoperative RT, 53.3% had postoperative RT, and bolus was used in 46.7%. Surgical margins were close (<1 mm) in 4 patients (20.0%) and positive in 10 patients (50.0%). LR occurred in the deep subfascial tissue in 9 patients (45%), subcutaneous tissue in 10 patients (50.0%), and skin in 1 patient (5.0%). The patient with a skin recurrence was treated with surgery alone, and the tumor involved the skin at presentation. In patients treated with RT, LR occurred within the RT field in 13 patients (86.7%). At 1 year after LR, progression-free survival was 70.3%, overall survival was 81.7%, and cumulative incidence of distant metastasis was 5.9%.

CONCLUSIONS

Skin recurrences were rare after surgical resection of STSs and only occurred in a tumor that involved the skin at initial presentation. These findings support current recommendations against routine use of bolus in STSs not involving the skin at presentation.

2023 Radiation oncology highlights

Radiation oncology plays an important role in the local treatment of cancers. Understanding recent advances in the application of radiation therapy to solid tumors is important for all disciplines. The radiation oncology section editors for this journal have selected the following articles for their overall significance, relevance to surgical oncologists, and to illustrate important concepts within the practice of radiation oncology.

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.

Team Approach: Extremity Soft Tissue Sarcoma

» Synovial sarcoma is a soft tissue sarcoma that most commonly presents in the extremity in a periarticular location.» As the history and physical examination of patients with synovial sarcoma can overlap considerably with those of patients with non-oncologic orthopedic conditions, it is important that orthopedic surgeons maintain a high level of suspicion when caring for patients with extremity masses.» Soft tissue sarcomas are best treated using a team approach. Early recognition and referral to a multidisciplinary sarcoma team are crucial to ensure the best clinical outcome for the patient.

Progression and Relapse of Pediatric Soft Tissue Sarcoma: Individualized Approach of Treatment - Experience from a Major Pediatric Cancer Center in Europe

BACKGROUND

The outcome of children with refractory or relapsed soft tissue sarcoma (STS) is extremely poor. Whereas larger clinical trials evaluated specific treatment modalities, real-life data on individual multimodal therapeutic strategies, given alone or in combination, are scarce.

PATIENTS AND METHODS

We retrospectively analyzed the clinical course of 18 pediatric patients with progression of or relapsed STS treated between 2008 and 2018 in our institution.

RESULTS

A total of 18 patients (median age 12.4 years) suffered from progression or relapse of alveolar (n=7), embryonal (n=5), undifferentiated (n=2) rhabdomyosarcoma or desmoplastic small round cell tumor (n=4). 14 patents had an initial stage IV disease. All but one patient died. Median survival was 12.5 months. Shortest survival was seen in patients with systemic progression of the disease, longest in patients with local relapse. Patients with an Oberlin score<2 at the time of relapse had a significant longer time of survival than those with a score≥2. No significant advantage of a specific therapeutic modality was observed.

DISCUSSION

We critically analyzed the clinical course in the real-life setting, in which various treatment options were applied to an individual patient according to the best of available data. We observed that some patients died within a short period of time despite multiple treatment modalities, which underlines the need for better prognostic parameters.

CONCLUSION

In addition to well characterized clinical factors such as local or systemic relapse, the Oberlin score could be helpful in counselling patients and their families for choosing the best strategy of care.

The role of radiation therapy in the management of primary retroperitoneal sarcoma: A systematic review and clinical practice guidelines from the Australia and New Zealand Sarcoma Association

While surgery is the mainstay of treatment for localised retroperitoneal sarcoma, the use of radiotherapy (RT) remains controversial. This systematic review aimed to evaluate the role of RT for retroperitoneal sarcoma. A systematic review using the population, intervention, comparison, and outcome model from 1990 to 2022 identified 66 studies (a mixture of preoperative and postoperative RT); one randomised controlled trial (RCT) with two publications, 18 registry studies, and 46 retrospective studies. In the RCT of preoperative RT, there was no difference in local/abdominal recurrence. The pooled analysis of this RCT and a retrospective study showed a significant abdominal recurrence free survival benefit with preoperative RT in low grade liposarcoma. The RCT and the majority of retrospective series found RT did not improve recurrence free survival (11 of 16 no difference in combined local and distant RFS, 11 of 13 no difference in distant metastasis free survival), disease specific survival (9 of 12 studies) or overall survival (33 of 49 studies). The majority of studies found no association between RT and perioperative morbidity. In summary, preoperative RT may improve local control for low grade (well-differentiated or grades 1-2 dedifferentiated) liposarcoma, but not other histological subtypes. There is no strong evidence that perioperative RT provides an overall survival benefit. Patients with low grade retroperitoneal liposarcoma can be considered for preoperative RT to improve abdominal recurrence free survival. The rationale and level of evidence in this scenario should be carefully discussed by the multidisciplinary team with patients. RT should not be routinely recommended for other histological subtypes.

Planning Strategy to Optimize the Dose-Averaged LET Distribution in Large Pelvic Sarcomas/Chordomas Treated with Carbon-Ion Radiotherapy

To improve outcomes in large sarcomas/chordomas treated with CIRT, there has been recent interest in LET optimization. We evaluated 22 pelvic sarcoma/chordoma patients treated with CIRT [large: HD-CTV ≥ 250 cm3 (n = 9), small: HD-CTV < 250 cm3 (n = 13)], DRBE|LEM-I = 73.6 (70.4-73.6) Gy (RBE)/16 fractions, using the local effect model-I (LEM-I) optimization and modified-microdosimetric kinetic model (mMKM) recomputation. We observed that to improve high-LETd distribution in large tumors, at least 27 cm3 (low-LETd region) of HD-CTV should receive LETd of ≥33 keV/µm (p < 0.05). Hence, LETd optimization using 'distal patching' was explored in a treatment planning setting (not implemented clinically yet). Distal-patching structures were created to stop beams 1-2 cm beyond the HD-PTV-midplane. These plans were reoptimized and DRBE|LEM-I, DRBE|mMKM, and LETd were recomputed. Distal patching increased (a) LETd50% in HD-CTV (from 38 ± 3.4 keV/µm to 47 ± 8.1 keV/µm), (b) LETdmin in low-LETd regions of the HD-CTV (from 32 ± 2.3 keV/µm to 36.2 ± 3.6 keV/µm), (c) the GTV fraction receiving LETd of ≥50 keV/µm, (from <10% to >50%) and (d) the high-LETd component in the central region of the GTV, without significant compromise in DRBE distribution. However, distal patching is sensitive to setup/range uncertainties, and efforts to ascertain robustness are underway, before routine clinical implementation.

Robust mixed electron-photon radiation therapy planning for soft tissue sarcoma

BACKGROUND

Mixed electron-photon beam radiation therapy (MBRT) is an emerging technique in which external electron and photon beams are simultaneously optimized into a single treatment plan. MBRT exploits the steep dose falloff and high surface dose of electrons while maintaining target conformity by leveraging the sharp penumbra of photons.

PURPOSE

This study investigates the dosimetric benefits of MBRT for soft tissue sarcoma (STS) patients.

MATERIAL AND METHODS

A retrospective cohort of 22 STS of the lower extremity treated with conventional photon-based Volumetric Modulated Arc Therapy (VMAT) were replanned with MBRT. Both VMAT and MBRT treatments were planned on the Varian TrueBeam linac using the Millenium multi-leaf collimator. No electron applicator, cutout or additional collimating devices were used for electron beams of MBRT plans. MBRT plans were optimized to use a combination of 6 MV photons and five electron energies (6, 9, 12, 16, 20 MeV) by a robust column generation algorithm. Electron beams in this study were planned at standard 100 cm source-axis distance (SAD). The dose to the clinical target volume (CTV), bone, normal tissue strip and other organs-at-risk (OARs) were compared using a Wilcoxon signed-rank test.

RESULTS

As part of the original VMAT treatment, tissue-equivalent bolus was required in 10 of the 22 patients. MBRT plans did not require bolus by virtue of the higher electron entrance dose. CTV coverage by the prescription dose was found to be clinically equivalent between plans of either modality:V 50Gy $V_{\text{50Gy}}$ (MBRT) = 97.9 ± 0.2% versusV 50Gy $V_{\text{50Gy}}$ (VMAT) = 98.1 ± 0.6% (p=0.34). Evaluating the absolute paired difference between doses to OARs in MBRT and VMAT plans, we observed lowerV 20Gy $V_{\text{20Gy}}$ to normal tissue in MBRT plans by 14.9 ± 3.2% (p < 10 - 6 $p<10^{-6}$ ). Similarly,V 50Gy $V_{\text{50Gy}}$ to bone was found to be decreased by 8.2 ± 4.0% (p < 10 - 3 $p<10^{-3}$ ) of the bone volume.

CONCLUSION

For STS with subcutaneous involvement, MBRT offers statistically significant sparing of OARs without sacrificing target coverage when compared to VMAT. MBRT plans are deliverable on conventional linacs without the use of electron applicators, shortened source-to-surface distance (SSD) or bolus. This study shows that MBRT is a logistically feasible technique with clear dosimetric benefits.

Managing spindle cell sarcoma with surgery and high-intensity focused ultrasound: A case report

BACKGROUND

Undifferentiated pleomorphic sarcomas, also known as spindle cell sarcomas, are a relatively uncommon subtype of soft tissue sarcomas in clinical practice.

CASE SUMMARY

We present a case report of a 69-year-old female patient who was diagnosed with undifferentiated spindle cell soft tissue sarcoma on her left thigh. Surgical excision was initially performed, but the patient experienced a local recurrence following multiple surgeries and radioactive particle implantations. High-intensity focused ultrasound (HIFU) was subsequently administered, resulting in complete ablation of the sarcoma without any significant complications other than bone damage at the treated site. However, approximately four months later, the patient experienced a broken lesion at the original location. After further diagnostic workup, the patient underwent additional surgery and is currently stable with a good quality of life.

CONCLUSION

HIFU has shown positive outcomes in achieving local control of limb spindle cell sarcoma, making it an effective non-invasive treatment option.

Neoadjuvant Simultaneous Integrated Boost Radiation Therapy Improves Clinical Outcomes for Retroperitoneal Sarcoma

PURPOSE

Neoadjuvant radiation therapy (RT) with standard techniques (ST) offers a modest benefit in retroperitoneal sarcoma (RPS). As the high-risk region (HRR) at risk for a positive surgical margin and recurrence is posterior and away from radiosensitive organs at risk, using a simultaneous integrated boost (SIB) allows targeted dose escalation to the HRR while sparing these organs. We hypothesized that neoadjuvant SIB RT can improve disease control compared with ST, without increasing toxicity.

METHODS AND MATERIALS

We retrospectively identified patients with resectable nonmetastatic RPS from 2000 to 2021 who received neoadjuvant RT of 180 to 200 cGy/fraction to standard volumes. SIB patients received 205 to 230 cGy/fraction to the appropriate HRR. Clinical endpoints included abdominopelvic control (APC), recurrence-free survival (RFS), overall survival (OS), and acute toxicity.

RESULTS

With a median follow-up of 57 months (95% confidence interval [CI], 50-64), there were 103 patients with RPS who received either ST (n = 69) or SIB (n = 34) RT. Median standard volume dose was 5000 cGy (ST) and 4500 cGy (SIB), with a median HRR SIB dose of 5750 cGy. Liposarcomas (79% vs 53%; P = .004) and cT4 tumors (59% vs 19%; P < .001) were more common in the SIB cohort, without a significant difference in the rate of resection (82% vs 81%; P = .88) or R1 margin (53.5% vs 50%; P = .36); there were no R2 resections. SIB was associated with a significant improvement in 5-year APC (96% vs 70%; P = .046) and RFS (60.2% vs 36.3%; P = .036), with a nonsignificant OS difference (90.1% vs 67.5%; P = .164). On multivariable analysis, SIB remained a predictor for APC (hazard ratio, 0.07; 95% CI, 0.01-0.74; P = .027) and RFS (hazard ratio, 0.036; 95% CI, 0.13-0.98; P = .045). SIB showed no significant detriment in toxicity, albeit with a lower rate of overall grade 3 acute toxicity (3% vs 22%; P = .023) compared with ST.

CONCLUSIONS

In RPS, dose escalation with neoadjuvant SIB RT may be independently associated with improved APC and RFS, without a detriment in toxicity, compared with ST. With the addition of standard RT having only a modest benefit compared with surgery alone, our study suggests that future prospective studies evaluating for the benefit of SIB RT should be considered.

High dose (54 Gy) pre-operative helical tomotherapy for retroperitoneal liposarcoma: Results of a phase II multicenter study

PURPOSE

To evaluate efficacy and feasibility of high-dose intensity-modulated radiotherapy (RT) with pre-operative helical tomotherapy, delivering 54 Gy/30 fractions in patients with retroperitoneal liposarcomas (RPLS).

MATERIALS AND METHODS

Patients with operable, biopsy-proven, RPLS were included in this phase II multicenter study (ClinicalTrials.gov: NCT01841047). The primary objectives were to analyze loco-regional relapse free survival (LRFS), overall survival (OS) and toxicities, graded according to CTCAE V3.0.

RESULTS

From April 2009 to September 2013, 48 patients were included. Histological types were: 20 well differentiated and 28 dedifferentiated liposarcomas. Median clinical target volume (CTV) was 2570 cc (range, 230-8734 cc). The radio-surgical schedule was completed as planned in all patients apart from one. A monobloc wide excision was achieved for all patients. Surgical margins were R0 (16; 34%), R1 (28; 60%), R2 (2; 4%) or missing (1, 2%).With a median follow-up of 5.5 years, 3-year LRFS rate was 74.2% (95%CI: [59.1%; 84.5%]). At 5 years, cumulative incidence of loco-regional relapse for well differentiated and dedifferentiated RPLS was 10% and 18%, respectively. The 5-year OS was 73.9% [95%CI: 58.7-84.3%]. During RT, the most common grade 3-4 adverse events were hematological (N = 20; 41.6%). After surgery and during follow-up, 17 patients (35.4%) presented a grade 3-4 toxicity. Two patients (4.1%) died due to a duodenal toxicity. Nine second cancers were observed.

CONCLUSION

From this phase II trial of preoperative RT in RPLS patients, the dose level proposed cannot be considered safe, leading to non-negligible toxicity and second cancers rates. Our results, combined with STRASS-1 study, suggest that the ideal indication of RT for patients with RPLS still remains to be determined.

Toxicity, normal tissue and dose-volume planning parameters for radiotherapy in soft tissue sarcoma of the extremities: A systematic review of the literature

BACKGROUND

Patients with soft tissue sarcoma of the extremities (STSE) are left with high incidence of toxicities after Radiotherapy (RT). Understanding the normal tissue dose relationship with the development of long-term toxicities may enable better RT planning in order to reduce treatment toxicities for STSE. This systematic review of the literature aims at reporting the incidence of acute and late toxicities and identifying RT delineation guidance the normal tissues structures and dose-volume parameters for STSE.

METHODS

A literature search of PUBMED-MEDLINE for studies that reported data on RT toxicity outcomes, delineation guidelines and dose-volume parameters for STSE from 2000 to 2022. Data has been tabulated and reported.

RESULTS

Thirty of 586 papers were selected after exclusion criteria. External beam RT prescriptions ranged from 30 to 72 Gy. The majority of studies reported the use of Intensity Modulated RT (IMRT) (27%). Neo-adjuvant RT was used in 40%. The highest long-term toxicities were subcutaneous and lymphoedema, reported when delivering 3DCRT. IMRT had a lower incidence of toxicities. Normal tissue outlining such as weight-bearing bones, skin and subcutaneous tissue, corridor and neurovascular bundle was recommended in 6 studies. Nine studies recommended the use of dose-volume constraints, but only one recommended evidence-based dose-volume constraints.

CONCLUSION

Although the literature is replete with toxicity reports, there is a lack of evidence-based guidance on normal tissue and dose-volume parameters and strategies to reduce the normal tissues irradiation when optimising RT plans for STSE are poor compared to other tumour sites.