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Caitlyn Kwan, BS



Job Title

Clinical Research Coordinator

Academic Rank


Radiation Oncology


Caitlyn Kwan BS, Yu-Hui Chen PhD, Mai Anh Huynh MD PhD

Principal Investigator

Mai Anh Huynh, MD PhD

Research Category: Cancer


Stereotactic Body Radiation Therapy for Femur Metastases

Scientific Abstract

Objective: We aim to identify patient or treatment factors associated with clinical outcomes among patients treated with stereotactic body radiation therapy (SBRT) to femur metastases for oligometastatic disease control.

Methods: We retrospectively reviewed 50 patients with 56 femur lesions, consecutively treated with SBRT at a single institution between May 2017-June 2022. Clinical characteristics were analyzed using the Kaplan-Meier method to characterize time-to-event endpoints and Cox proportional hazards models to evaluate the associations between baseline factors and clinical outcomes.

Results: The median follow up was 19.4 months. Most patients had prostate (n=50%) or breast/lung (16%) cancer and 1-3 lesions (94%), including 30 proximal and 5 distal.

43% had Mirel’s score ≥ 7. Acute toxicities included grade 1 fatigue (14.3%), pain flare (7.1%), and decreased blood counts (1.8%). Late toxicities included fracture (1.8%) at 1.5 years and radiation-induced osteonecrosis (1.8%) from dose of 40Gy in 5F. Five patients (n=10%) required fixation post-radiation due to progression of disease or symptoms. The 1 and 2-year rates of LC were 84% and 69%, PFS were 55% and 27%, and OS were 91% and 74%.

Conclusion: Femur SBRT for oligometastatic disease control was associated with good outcomes with minimal rates of acute or late toxicity.

Lay Abstract

The use of high doses of radiation has been shown to improve how long people live for patients with limited burden of cancer. Due to fear of causing a fracture, doctors have been hesitant to apply high radiation doses to the femur. The SABR-COMET trial demonstrated survival benefits of increasing dosages for limited burden of cancer patients but did not include any femur patients. We looked at a large group of femur patients to determine if high doses of radiation can be done safely and efficiently. The results show high doses may be beneficial to help people live longer with a low risk of femur fracture.

Clinical Implications

This is a large institutional study demonstrating the safety and efficacy of high dose radiation to the femur and should be considered for patients. Further studies are warranted to evaluate how to balance avoiding fracture and toxicities with good outcomes.