Main Session
Sep
27
PQA 02 - Pediatric Cancer, Sarcoma and Cutaneous Tumors, Medical Education & Professional Development, and Health Services Research
2346 - Brachytherapy vs. External Beam Radiation In Gynecologic Rhabdomyosarcoma: A Retrospective Survival Analysis
Presenter(s)
Luke Limfueco, BS - Western University of Health Sciences, College of Osteopathic Medicine of the Pacific, Pomona, CA
L. Limfueco1, A. L. Schwer2, A. Amini3, S. M. Glaser3, H. Kim3, S. Sampath3, V. L. Williams3, B. Nakamura4, J. Kim4, L. G. Brunette4, J. G. Cohen4, and C. J. Ladbury2,3; 1Western University of Health Sciences, College of Osteopathic Medicine of the Pacific, Pomona, CA, United States, 2Department of Radiation Oncology, Orange County Lennar Foundation Cancer Hospital, Irvine, CA, 3Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA, 4Department of Gynecologic Oncology, City of Hope National Medical Center, Duarte, CA
Purpose/Objective(s):
Traditionally, rhabdomyosarcoma (RMS) is treated with chemotherapy combined with surgery and/or radiation. For gynecologic (GYN) RMS, due to morbidity of surgery, radiation might be preferred, though there are concerns about long-term sequelae. Brachytherapy (BT) represents a potential alternative to external beam radiation therapy (EBRT), offering localized dosing that minimizes toxicity while preserving organ structure and function. Herein, we analyze survival outcomes in patients treated with EBRT alone and BT-containing regimens for GYN RMS.Materials/Methods:
This retrospective cohort study utilized National Cancer Database (NCDB) data (2004–2022) to compare patients with GYN RMS treated with EBRT or BT-containing regimens. Overall survival (OS) was estimated using the Kaplan-Meier method and a multivariate Cox proportional hazards model evaluated the impact of radiation modality on survival while adjusting for covariates.Results:
A total of 290 patients with a confirmed diagnosis of GYN RMS treated with radiation therapy were identified. The median year of diagnosis was 2015 (IQR 2010–2018), with a median follow-up of 46 months (IQR 19–86), and a median age of 16 years old (IQR 4–48). Of these patients, 74 received BT-containing regimens and 216 received EBRT alone. Of the patients who received BT, 18 received it in combination with EBRT. Tumor size and tumor staging data were limited, thus extent of surgical resection was used as a surrogate for disease extent. 85% of patients who received BT underwent primary surgical resection or debulking compared to 56% of patients receiving EBRT alone (p<0.01). BT was associated with higher OS compared to EBRT at 1 year (93% vs. 86%, p < 0.01), 3 years (89% vs. 66%, p < 0.01), and 5 years (84% vs. 60%, p <0.01). After adjusting for covariates associated with overall survival—such as age, tumor histology, surgical resection, and comorbidities—BT-containing regimens were associated with improved OS compared to EBRT alone (HR 0.47, 95% CI: 0.26–0.85, p =0.013). Among patients who underwent BT, pediatric age (0-17 years old) was associated with improved OS (HR 0.19, 95% CI: 0.04-0.85, p=0.03), while uterine tumors were associated with worse OS (HR 5.52, 95% CI: 1.53-19.8, p=0.009). Among patients who underwent surgery, BT containing regimens were associated with improved OS compared to EBRT (HR 0.50, 95% CI 0.26-0.96, p=0.038). When controlling for surgery, BT containing regimens were associated with improved OS compared to EBRT among pediatric patients (HR 0.22, 95% CI 0.05-0.92, p=0.039), but not for adult patients (HR 0.56, 95% CI 0.29-1.07, p=0.08)Conclusion:
Brachytherapy is an effective therapeutic modality for GYN RMS, with favorable long-term survival. Although external beam radiation remains the more commonly selected modality in the US, brachytherapy might be considered for appropriately selected cases. This may be particularly pertinent in pediatric patients where there is concern for secondary malignancy.