Abstract
Bone metastasis is a common complication in breast and prostate cancers, characterized by severe pain and a high risk of fractures. Its treatment includes several strategies, notably stereotactic body radiation therapy (SBRT).
The objective of this study is to evaluate the efficacy of SBRT in pain control, the incidence of treatment-related fractures, and to identify factors associated with clinical response to pain treatment.
The medical records of 97 patients treated between 2021 and 2024 were retrospectively reviewed. The metastases were irradiated with SBRT, administering 36 Gy to the GTV and 27 Gy to the CTV in 3 fractions. Statistical analyses were performed with Statistica version 14.0.0.1, using a significance value of p≤0.05.
In 97 patients, 214 metastases were treated, 42 were asymptomatic (19.6%), and 172 (80.4%) presented pain at diagnosis. Of these, 129 (60.3%) responded to treatment, with improvement greater than 50% in 75.2% of cases; 43 lesions (20.1%) did not respond.
No statistically significant differences were observed in response to treatment in relation to metastasis volume, primary diagnosis, age, gender, or ECOG-PS. The response time was immediate in 74%, at one month in 16%, and at three months in 10%. Only two fractures were recorded, both in large lesions with prolonged follow-up.
Although this is a retrospective study, the results suggest that SBRT is effective and safe for the management of pain associated with bone metastases, with a low rate of associated fractures.
Introduction
Bone is one of the most common sites of metastatic disease, with approximately 70% originating from prostate or breast cancer. Patients generally report increasing pain when the lesion is located anywhere in the skeleton. Metastasis can replace the normal bone matrix, causing spontaneous or pathological fractures, which are more common in long bones. Some patients seek medical attention for neurological symptoms when the metastasis is located in the vertebrae and invades the spinal canal, compressing the spinal cord. The treatment of bone metastases can be pharmacological with bisphosphonates, analgesics, corticosteroids, chemotherapy, and hormone therapy. Local management includes surgery, radiotherapy, or a combination of both. For more than four decades, conventional radiotherapy (CRT) has been used, administering 20 Gy/5 fractions, 30 Gy/10 fractions, or a single dose of 8 Gy. All of these fractionations are safe for adjacent normal tissues; however, they have shown a partial and short-term pain response, with a high recurrence rate requiring re-irradiation. High-precision stereotactic body radiotherapy (SBRT) allows for the administration of a biologically effective dose (BED) that is higher than that of CRT. This technique enables the delivery of high doses per fraction over a period of 1 to 5 days, minimizing the exposure of healthy tissues to doses that exceed their tolerance threshold. SBRT is currently an accepted therapeutic option for the treatment of single bone metastases, oligometastases, or multiple lesions in patients who are in pain or at risk of fracture or spinal cord compression, regardless of skeletal location. It is widely recognized that radiation has the ability to alter the bone matrix and reduce blood circulation, effects that increase with the dose administered and predispose the irradiated bone to fracture. Farugi et al. reviewed 11 studies in which 2,911 vertebral metastases were irradiated with SBRT. The authors reported that the rate of vertebral fracture after SBRT was 13.9%. The primary objective of this retrospective study was to evaluate the clinical response to pain and the frequency of fractures after SBRT in a series of patients with bone metastases, including vertebral metastases, treated with SBRT for three consecutive days. The secondary objective was to identify factors associated with pain response in this patient cohort.
Verónica Vera Merino, Daniela Ángel Shutte, Debora Middendorf, María José Almada, Daniel Venencia, Mario Borra, Silvia Zunino
Zunino Institute, Marie Curie Foundation, Córdoba, Argentina
To download the complete research, click below:
https://oncologiaclinica.aaoc.org.ar/index.php/oncologiaclinica/article/view/212/161
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