Could Five Be the New Twenty-Five? Long-term Oncologic Outcomes from a Phase II, Prospective, 5-Fraction Pre-operative Radiation Therapy Trial in Patients with Localized Soft Tissue Sarcoma

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.

Meta-Analysis of 5-Fraction Preoperative Radiotherapy for Soft Tissue Sarcoma

OBJECTIVES

Studies investigating preoperative 5-fraction radiation therapy (RT) for soft tissue sarcoma (STS) are limited. We performed a meta-analysis to determine the efficacy and safety of this treatment paradigm.

METHODS

This study-level meta-analysis was conducted using Bayesian methods. Statistical estimation for risk of outcome rates was conducted by posterior mean and 95% highest posterior density (HPD) intervals. Studies with 2-year local control (LC) and description of major wound complications (MWC) per the CAN-NCIC-SR2 study were included and served as the primary endpoints. Secondary endpoints included rates of acute and late toxicity. A total of 10 studies were identified and 7 met the inclusion criteria. Subgroup analyses were performed for ≥30 Gy vs <30 Gy.

RESULTS

A total of 209 patients from 7 studies were included. Five studies used ≥30 Gy (n=144), and 2 studies <30 Gy (n=64). Median follow-up was 29 months (range: 21 to 57 mo). Primary tumor location was lower extremity in 68% and upper extremity in 22%. Most tumors were intermediate or high grade (95%, 160/169), and 50% (79/158) were >10 cm. The two-year LC for the entire cohort was 96.9%, and the rate of MWC was 30.6%. There was a trend toward improved LC with ≥ 30 Gy (95% HPD: 0.95 to 0.99 vs 0.84 to 0.99). There was no difference in MWC (95% HPD: 0.18 to 0.42 vs 0.17 to 0.55) or late toxicity between the groups.

CONCLUSION

Preoperative 5-fraction RT for STS demonstrates excellent 2-year LC with MWC and toxicity similar to standard fractionation preoperative RT. Multi-institutional trials with a universal RT protocol are warranted.

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).

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.

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.

Surgical Margins in Musculoskeletal Sarcoma

» Negative margin resection of musculoskeletal sarcomas is associated with reduced risk of local recurrence.» There is limited evidence to support an absolute margin width of soft tissue or bone that correlates with reduced risk of local recurrence.» Factors intrinsic to the tumor, including histologic subtype, grade, growth pattern and neurovascular involvement impact margin status and local recurrence, and should be considered when evaluating a patient's individual risk after positive margins.» Appropriate use of adjuvant therapy, critical analysis of preoperative advanced cross-sectional imaging, and the involvement of a multidisciplinary team are essential to obtain negative margins when resecting sarcomas.

Moderate hypofractionated radiation therapy and pathologic response for soft tissue sarcomas (STS) of limbs and trunk: experience from a tertiary cancer center

BACKGROUND

Preoperative radiation therapy following by limb-sparing or conservative surgery is a standard approach for limb and trunk STS. Data supporting hypofractionated radiotherapy schedules are scarce albeit biological sensitivity of STS to radiation would justify it. We sought to evaluate the impact of moderate hypofractionation on pathologic response and its influence on oncologic outcomes.

MATERIAL AND METHODS

From October 2018 to January 2023, 18 patients with limb or trunk STS underwent preoperative radiotherapy at a median dose of 52.5 Gy (range 49.5-60 Gy) in 15 fractions of 3.5 Gy (3.3-4 Gy) with or without neoadjuvant chemotherapy. A favorable pathologic response (fPR) was considered as ≥ 90% tumor necrosis on specimen examination.

RESULTS

All patients completed planned preoperative radiotherapy. Eleven patients (61.1%) achieved a fPR, and 7 patients (36.8%) a complete pathologic response with total disappearance of tumor cells. Nine patients (47%) developed grade 1-2 acute skin toxicity, and 7 patients (38.8%) had wound complications on follow-up. With a median follow-up of 14 months (range 1-40), no cases of local relapse were observed, and actuarial 3-year overall survival (OS) and distant metastases-free survival (DMFS) are 87% and 76.4%, respectively. In the univariate analysis, the presence of a favorable pathologic response (fPR) was associated with improved 3-year OS (100% vs. 56.03%, p = 0.058) and 3-year DMFS (86.91% vs. 31.46%, p = 0.002). Moreover, both complete or partial RECIST response and radiological stabilization of the tumor lesion showed a significant association with higher rates of 3-year distant metastasis-free survival (DMFS) (83% vs. 83% vs. 56%, p < 0.001) and 3-year overall survival (OS) (100% vs. 80% vs. 0, p = 0.002).

CONCLUSIONS

Preoperative moderate hypofractionated radiation treatment for STS is feasible and well tolerated and associates encouraging rates of pathologic response that could have a favorable impact on final outcomes.

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.

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.

Comparative In Silico Analysis of Ultra-Hypofractionated Intensity-Modulated Photon Radiotherapy (IMRT) Versus Intensity-Modulated Proton Therapy (IMPT) in the Pre-Operative Treatment of Retroperitoneal Sarcoma

BACKGROUND

While pre-operative radiation did not improve abdominal recurrence-free survival for retroperitoneal sarcoma (RPS) in the randomized STRASS trial, it did reduce rates of local recurrence. However, the risk of toxicity was substantial and the time to surgery was prolonged. A combination of hypofractionation and proton therapy may reduce delays from the initiation of radiation to surgery and limit the dose to surrounding organs at risk (OARs). We conducted a dosimetric comparison of the pre-operative ultra-hypofractionated intensity-modulated photon (IMRT) and proton radiotherapy (IMPT).

METHODS

Pre-operative IMRT and IMPT plans were generated on 10 RPS patients. The prescription was 25 Gy radiobiological equivalents (GyEs) (radiobiological effective dose of 1.1) to the clinical target volume and 30 GyEs to the margin at risk, all in five fractions. Comparisons were made using student T-tests.

RESULTS

The following endpoints were significantly lower with IMPT than with IMRT: mean doses to liver, bone, and all genitourinary and gastrointestinal OARs; bowel, kidney, and bone V5-V20; stomach V15; liver V5; maximum doses to stomach, spinal canal, and body; and whole-body integral dose.

CONCLUSIONS

IMPT maintained target coverage while significantly reducing the dose to adjacent OARs and integral dose compared to IMRT. A prospective trial treating RPS with pre-operative ultra-hypofractionated IMPT at our institution is currently being pursued.

Leiomyosarcoma of the lower rectum managed by radiotherapy and surgery: A case report and review of literature

Rectal leiomyosarcoma is a very rare entity. Surgery is the main treatment, but the place of radiation therapy remains unclear. A 67-year-old woman was referred for a few-weeks' history of bleeding and anal pain intensified during defecation. Pelvic magnetic resonance imaging (MRI) showed a rectal lesion and biopsies revealed a leiomyosarcoma of the lower rectum. She was free of metastasis on computed tomography imaging. The patient refused radical surgery. After discussion by a multidisciplinary team, the patient received pre-operative long-course radiotherapy followed by surgery. The tumor was treated with 50Gy delivered in 25 fractions, within 5 weeks. The aim of radiotherapy was local control, allowing organ-preservation. Four weeks after radiation therapy, organ-preservation surgery could be performed. She had no adjuvant treatment. At 38-months follow-up, she had no local recurrence. However, distant recurrence (lung, liver, and bone) was detected 38 months after the resection and was managed by intra-venous doxorubicin 60mg/m² and dacarbazine 800mg/m² every 3 weeks. The patient was in a stable condition for nearly 8 months. The patient died 4 years and 3 months after the diagnosis.

Early outcomes of ultra-hypofractionated preoperative radiation therapy for soft tissue sarcoma followed by immediate surgical resection

BACKGROUND

There is increasing interest in shorter courses of radiation therapy (RT) in the management of soft tissue sarcoma (STS). We report our institutional experience for patients undergoing ultra-hypofractionated preoperative RT followed by immediate resection.

METHODS

An IRB approved review of patients treated with preoperative 5 fraction, once daily RT followed by immediate resection (within 7 days) for STS of the extremity or trunk was conducted. The primary endpoints are major wound complications and local control (LC). Secondary endpoints include grade ≥ 2 toxicity, metastasis free survival (MFS), and overall survival (OS).

RESULTS

Twenty-two patients with a median age of 67 years (range 30-87) and median follow-up of 24.5 months (IQR 17.0-35.7) met eligibility criteria; 18/22 patients (81.8 %) had ≥ 1 year follow-up. Primary tumor location was lower extremity in 15 patients (68.2 %), upper extremity in 5 (22.7 %), and trunk in 2 (9.1 %). All patients received 30 Gy in 5 fractions. The median time to resection following RT was 1 day (range 0-5). The median time from biopsy to resection was 34 days (range 20-69). Local control was 100 %; in patients with localized disease, 2-year MFS and OS were 71.3 % and 76.9 %, respectively. Major wound complications occurred in 9 patients (40.9 %), with wound complications requiring reoperation occurring in 8 patients (36.4 %). Other acute and late grade ≥ 2 toxicities were seen in 0 and 4 patients (18.2 %), respectively.

CONCLUSION

Ultra-hypofractionated preoperative RT followed by immediate resection permits expedited completion of oncologic therapy with early results demonstrating excellent local control and acceptable toxicity. Prospective data with long-term follow-up is needed.

Safety and feasibility of short course pre-operative radiation therapy followed by surgical excision for canine solid tumours

Surgical resection of solid tumours, especially in early stages of disease, remains a cornerstone of cancer treatment in dogs and cats. There are numerous publications that show a strong association between local tumour control and outcome. To achieve local control in some cases radiation therapy and surgery are combined, with radiation therapy being delivered in the neoadjuvant or adjuvant setting. The objective of the study was to report acute toxicity and surgical site complication data in dogs that received a short-course pre-operative (SCPO) radiation therapy protocol, followed by surgical excision for various solid tumours. Medical records were reviewed, and data was analysed retrospectively. Dogs were included if a dermal or subcutaneous solid tumour was treated with SCPO radiation therapy and then was resected on the last day of radiation or 2-3 weeks later. A total of 34 dogs with 35 primary tumours were included. Acute radiation toxicity was diagnosed in 14 sites (40%). VRTOG scores were grade 1 in 50%, grade 2 in 43%, and grade 3 in 7%. Surgical site complications were identified in 17% of dogs with an overall surgical site infection rate of 11%. According to the Clavien-Dindo classification, two dogs required medical intervention (grade 2), 1 dog required surgical intervention under general anaesthesia (grade 3b), and 1 dog died as a result of complications (grade 5). Logistic regression analysis found that anatomic site was significantly associated with complications, where tumours located on the extremity was protective (P = .02; OR 0.06).

Comparing Ultra-hypofractionated Proton versus Photon Therapy in Extremity Soft Tissue Sarcoma

Purpose

Recent single institution, phase II evidence has demonstrated the feasibility and efficacy of ultra-hypofractionated, preoperative photon therapy in 5 fractions for the treatment of soft tissue sarcoma (STS). Our purpose was to evaluate the dosimetric benefits of modern scanning beam proton therapy compared with conventional photon radiation therapy (RT) for the neoadjuvant treatment of adult extremity STS.

Materials and Methods

Existing proton and photon plans for 11 adult patients with STS of the lower extremities previously treated preoperatively with neoadjuvant RT at our center were used to create proton therapy plans using Raystation Treatment Planning System v10.A. Volumes were delineated, and doses reported consistent with International Commission on Radiation Units and Measurements reports 50, 62, and 78. Target volumes were optimized such that 100% clinical target volume (CTV) was covered by 99% of the prescription dose. The prescribed dose was 30 Gy for PT and RT delivered in 5 fractions. For proton therapy, doses are reported in GyRBE = 1.1 Gy. The constraints for adjacent organs at risk (OARs) within 1 cm of the CTV were the following: femur V30Gy ≤ 50%, joint V30Gy < 50%, femoral head V30Gy ≤ 5 cm3, strip V12 ≤ 10%, and skin V12 < 50%. Target coverage goals, OAR constraints, and integral dose were compared by Student t test with P < .05 significance.

Results

A minimum 99% CTV coverage was achieved for all plans. OAR dose constraints were achieved for all proton and photon plans; however, mean doses to the femur (10.7 ± 8.5 vs 16.1 ± 7.7 GyRBE), femoral head (2.0 ± 4.4 vs 3.6 ± 6.4 GyRBE), and proximal joint (1.8 ± 2.4 vs 3.5 ± 4.4 GyRBE) were all significantly lower with PT vs intensity-modulated radiation therapy (IMRT) (all P < .05). Integral dose was significantly reduced for proton vs photon plans. Conformity and heterogeneity indices were significantly better for proton therapy.

Conclusion

Proton therapy maintained target coverage while significantly reducing integral and mean doses to the proximal organs at risk compared with RT. Further prospective investigation is warranted to validate these findings and potential benefit in the management of adult STS.