Radiation Therapy Plus Surgery May Improve Local Control in Localized Pelvic Ewing Sarcoma

The addition of surgery to radiation therapy led to improved local control compared with radiation therapy alone in patients with localized pelvic Ewing Sarcoma, according to a retrospective study published by the Children’s Oncology Group in the International Journal of Radiation Oncology, Biology, Physics.

Patients (n = 101) treated with radiation therapy (68%) and surgery plus radiation therapy (32%) had local failure rates of 25.0% and 6.3%, respectively (P = .046). The highest local failure incidence occurred in tumors that originated in the ischiopubic-acetabulum region at a rate of 37.5% vs sacrum and iliac/buttock tumors (P = .02), particularly those treated with radiation therapy alone, with a local recurrence rate of 50.0% (P = .06). Additionally, with every additional 100 mL of tumor at diagnosis, there was a higher incidence of local failure (P = .04).

“This study shows us that there probably is a role for combined modalities for local control in patients with Ewing sarcoma,” R. Lor Randall, MD, FACS, said. “We shouldn’t just be doing surgery or radiation; we might want to figure out a way by which we would randomize high-risk patients to surgery and radiotherapy.”

In an interview with OncLive^®, Randall, The David Linn Endowed Chair for Orthopaedic Surgery, chair of the Department of Orthopaedic Surgery, and a professor at UC Davis Comprehensive Cancer Center in Sacramento, California, discussed the significance of the analysis.

OncLive^®: Please describe the background for this study.

Randall: This study from the Children’s Oncology Group looked at patients with pelvic Ewing sarcoma treated with radiation or radiation and surgery. The study highlights the fact that we have difficulty with local control for Ewing sarcoma in the pelvis. Traditionally, in the United States pelvic Ewing’s has been treated with surgery or radiation and generally not a combined modality approach, but there’s a certain cohort of patients for a variety of reasons that do need radiation in addition to surgery when they’re scheduled for surgery.

[In this group of] approximately 100 patients that were treated with radiation or surgery and radiation, local control was more effective in the patients treated with surgery and radiation compared with radiation alone. It’s important to point out this was a [retrospective study]. This was not a study designed to randomize patients to radiation or radiation plus surgery.

The local recurrence rate was 25% for radiation alone and 6.3% with surgery and radiation, and this was statistically significant. We also found that tumor involvement around the ischial acetabular area was associated with the highest local failure and that the sacrum was a challenge.

Local failure usually will happen within the first 2 years and certainly within the first 5 years, so we wanted to be as inclusive as we could [and] kept it at 5 [years follow-up]. The risk of local recurrence after 5 years is very small.

Did any of these findings come as a surprise to you?

No, [but the study] did demonstrate to us that we shouldn’t be so exclusionary in our thinking, meaning patients should only get surgery or only get radiation. This data does support the idea that combined modality therapy can optimize local control in Ewing’s of the pelvis. This study has raised the discussion and makes us as a cooperative group entertain the idea of potentially [conducting] a prospective randomized trial around local control in Ewings.

Do you anticipate any challenges to enrollment if such a trial is initiated?

Yes, both from familial [and individual] anxieties around having both modalities which have their own sets of complications. Now you’re doubling those risks because you’re doing both [treatments]. Also, there are some staunch surgeons and staunch radiation therapists that feel very strongly, despite what this data shows, that one way or the other way is better.

What is your take-home message to colleagues?

The take home for the medical oncologist and others that are interested in managing bone sarcomas, in particular Ewing’s sarcomas that are radio sensitive, is that we do need to consider the role of combined modality therapy in difficult to treat cases. All Ewing’s of the pelvises are not equal in terms of local morbidity and local control. For cases that are amenable to surgery and can get a wide negative margin with minimal patient morbidity, relatively speaking, surgery should be entertained. For those that are so massive that surgery would be so morbid, and we know local control can be affected with radiation alone, those should be treated with radiation. But there is a middle group where we still have a significant relapse [rate] with radiation that we should be [treating with] radiation and surgery. Unfortunately, we have to come up with some criteria to be able to randomize [patients to] to answer the question.

Reference

Ahmed SK, Witten BG, Harmsen WS, et al. Analysis of local control outcomes and clinical prognostic factors in localized pelvic Ewing sarcoma patients treated with radiation therapy: a report from the Children’s Oncology Group.Int J Radiat Oncol Biol Phys. 2022;S0360-3016(22)02590-1. doi:10.1016/j.ijrobp.2022.07.1840