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

Local Control in Soft Tissue Sarcomas

Soft tissue sarcoma is a rare heterogeneous group of tumors made up of over 100 histologic types and subtypes. Expert pathology review is crucial to confirm the correct diagnosis prior to treatment. Multidisciplinary discussion and management at an expert center is strongly recommended given the many nuances of treatment. Wide resection +/- preoperative radiotherapy is recommended in most extremity and trunk wall STS patients, while a minority may also require perioperative medical therapy. Macroscopic complete resection remains the standard of care for retroperitoneal sarcoma patients, with preoperative radiotherapy recommended in selected histologic types.

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.

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.

Preoperative radiotherapy combined with surgery versus surgery alone for primary retroperitoneal sarcoma: a meta-analysis

The efficacy of preoperative radiotherapy combined with surgery (preRT + S) for primary retroperitoneal sarcoma (RPS) remains unclear. This study aimed to compare preRT + S with surgery alone (SA) in patients with RPS. Core databases were searched for directly comparative studies depending on preRT. Thirteen studies included 2,439 patients with SA and 1,453 with preRT + S. PreRT + S in all RPS patients led to significantly low local recurrence (LR) (hazard ratios [HR],0.575; p = 0.008) compared to SA. Among the liposarcoma patients, PreRT + S did not clearly affect LR or abdominal recurrence-free survival (ARFS). Excluding dedifferentiated liposarcoma (DDLPS), the patients underwent preRT + S significantly improved LR (HR,0.430; p = 0.002) and ARFS (HR,0.706; p = 0.045). In another subgroup analysis of patients with well-differentiated liposarcoma and grade 1-2 DDLPS, preRT + S significantly extended ARFS (HR,0.601; p = 0.014) compared to SA. There was no significant difference in overall survival (OS) (HR,0.904; p = 0.362 [RPS]; HR,0.724; p = 0.348 [WDLPS + G1-2DDLPS]) between preRT + S and SA in all comparisons. PreRT + S group demonstrated higher incidence of total (odds ratio [OR],1.580; p = 0.007) and severe (OR,3.680; p = 0.004) complications than the SA group. PreRT + S prevent recurrence in patients with WDLPS and low-grade DDLPS but is associated with increased complications, resulting in similar OS compared to SA.

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.