Escalation of stereotactic ablative radiotherapy as metastasis-directed therapy
Stereotactic ablative body radiotherapy (SABR or SBRT) is a precise radiation therapy used for extracranial tumors, delivering high doses in one or a few sessions for effective tumor eradication. Its focused approach minimizes damage to surrounding tissues, making it ideal for metastatic cancer management. SBRT serves as a non-invasive Metastasis-Directed Therapy (MDT) for oligometastatic disease, achieving long-term control, and for palliative care in conditions like bone metastases. This research explores SBRT applications, evaluating its efficacy in disease control and patient outcomes. The first part of the thesis focuses on SABR for oligometastases. The DESTROY trial tested three fractionation schedules for non-spine bone and lymph node metastases. No grade ≥3 toxicity occurred among 90 patients, and despite lower PTV coverage in the 5-fraction cohort, local control was comparable. After a median follow-up of 50 months, grade 2 toxicity was comparable between the three arms, and local control rate was 93% at 4 years. Overall, all three schedules were feasible, effective, with low toxicity, highlighting the convenience of the single-fraction approach. Additionally, as SABR is commonly used for oligometastatic prostate cancer, which typically follows a relatively indolent disease progression with frequent relapses in the regional pelvic lymph nodes and predominantly metastasizes to the skeleton, we investigated the outcomes of SABR for both bone and nodal metastases in a real-life cohort of prostate cancer patients at our centre, finding a median disease-free survival of 22 months for hormone-sensitive prostate cancer (HSPC). Combining SABR with short-term androgen-deprivation therapy improved progression-free survival in specific HSPC cases. At 18 months, 2 in 5 patients remained free from relapse, identifying true oligometastatic cases. In the second part of the thesis, we explore SBRT's impact on pain palliation for bone metastases, known for causing severe pain. The ROBOMET trial compared a single SBRT fraction of 20 Gy with a single conventional fraction of 8 Gy. While SBRT didn't significantly improve pain response after one month, it outperformed conventional radiotherapy after three months. Dose-escalated SBRT achieved over 50% complete pain response compared to 31% with conventional radiotherapy, particularly benefiting patients with better prognoses. While not advantageous for patients with short life expectancy, SBRT demonstrated improved pain response durability for those with more favorable prognoses. This comprehensive exploration underscores SBRT's versatility in managing oligometastases and mitigating metastatic bone pain, shedding light on its efficacy and impact on patient well-being.
Antwerp : University of Antwerp, Faculty of Medicine and Health Sciences , 2023
161 p.
Supervisor: Dirix, Piet [Supervisor]
Supervisor: Meijnders, Paul [Supervisor]
Supervisor: van Laere, Steven [Supervisor]
Supervisor: Verellen, Dirk [Supervisor]
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Creation 12.12.2023
Last edited 04.03.2024
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