ASTRO Publishes Clinical Guidelines for Radiotherapy in Soft Tissue Sarcoma

The American Society for Radiation Oncology (ASTRO) has published a new evidence-based guidance for the use of radiation therapy in adult patients with soft tissue sarcoma based on currently published data, according to a publication from the organization Practical Radiation Oncology.¹

The use of radiotherapy is currently recommended among patients with soft tissue sarcoma who are at an increased risk of local recurrence of resected disease, especially if close or microscopic margins are anticipated or have occurred. Preoperative use of radiotherapy is strongly recommended over postoperative radiotherapy, where indicated. Notably, the use of postoperative radiotherapy is only recommended under specific clinical circumstances such as in patients with uncontrolled pain or bleeding; it also warrants use when the risk of wound complications outweigh late radiotherapy toxicity. Moreover, ASTRO does not recommend the routine use of radiotherapy in combination with oncologic resection for retroperitoneal sarcoma. For this population of patients, the guidelines state that preoperative radiotherapy should be used instead.

“Management of soft tissue sarcoma can be complicated, with the potential for poor outcomes and significant morbidity if treated suboptimally. The addition of radiation therapy to surgery reduces the chance of local recurrence,” Kilian E. Salerno, MD, vice chair of the guideline task force and a radiation oncologist at the National Cancer Institute, said in a press release.² “This guideline stresses the importance of multidisciplinary input prior to initiation of treatment and provides detailed recommendations on indications for radiation therapy, dose, and planning techniques. ASTRO developed this guideline to provide clear guidance on the role of radiation therapy in patient-centered, multidisciplinary oncologic care.”

The guidelines were reviewed by 19 peer reviewers. The modified guideline was published on ASTRO’s website for public comment from November 2020 to January 2021. The guidelines were based on a systemic literature review that included literature that had been published from January 1980 to September 2020.

Experts in the field considered studies that featured patients who were 18 years or older with a primary diagnosis of localized soft tissue sarcoma, involving the extremity, superficial trunk, or retroperitoneum. Study treatments needed to utilize surgical resection and radiotherapy.

The updated guideline included insights into the role of radiotherapy in adult patients with operable, localized disease of the extremity and trunk, as well as highlighting the complexities of utilizing the therapy to treat retroperitoneal sarcoma.

Additional guidelines indicated that for patients with localized disease, expert pathology and radiology review, as well as multidisciplinary evaluation should be utilized prior to beginning treatment.

Determinants of increased local recurrence include clinical, pathologic, and surgical factors such as surgical margins, grade, tumor size, anatomic location, and histopathologic subtype. Additionally, resection margin status was noted as being a major and consistent factor that can be utilized to predict local disease recurrence.

When selecting between preoperative and postoperative radiotherapy in the treatment of extremity, the optimal sequencing should include multidisciplinary evaluation, as previously stated. Both therapies yield comparable local control when combined with surgery, however the differences in risk of acute vs late morbidity are worth noting. Following oncologic resection, unanticipated complications may occur such as inadequate margins, fascia invasion, higher grade disease, or infiltrative or discontinuous spread which in turn may increase the risk of recurrence. Postoperative radiotherapy could be utilized in this scenario, the guidelines stated.

In terms of recommendations for dosing and fractionations, ASTRO strongly recommends that this patient population receive preoperative radiotherapy at a dose of 5000 cGy in 25 once daily fractions or 5040 cGY in 28 once daily fractions to clinical target volume (CTV)1 and an additional dose to a reduced volume for CTV2. Anatomically constrained CTV is recommended for this patient population.

“When radiation is indicated, it generally should be given before surgery because the long-term [adverse] effects [AEs] are less severe,” B. Ashleigh Guadagnolo, MD, MPH, chair of the guideline task force and a professor of radiation oncology at The University of Texas MD Anderson Cancer Center, concluded. “The [AEs] of preoperative radiation therapy can be serious, but they are reversible. Postoperative radiation therapy [AEs], however, are, in many cases, permanent because more radiation dose is required when given after surgery, and it often needs to be given to a larger area of the body.”

References

1. Salerno KE, Alektiar KM, Baldini EH, et al. Radiation therapy for treatment of soft tissue sarcoma in adults: executive summary of an ASTRO clinical practice guideline. Prac Rad Oncol. Published online July 25, 2021. doi:10.1016/j.prro.2021.04.005
2. ASTRO issues clinical guideline on radiation therapy for soft tissue sarcoma in adults. News release. American Society for Radiation Oncology. July 27, 2021. Accessed August 30, 2021. https://bit.ly/3BDHTX5