Stereotactic body radiotherapy (SBRT), or stereotactic ablative body radiotherapy (SABR), is an innovative radiation therapy technique. The technique uses special equipment to precisely deliver a dose of radiation to a tumor. SBRT aims to employ the highest possible dose of radiation to kill cancer while minimizing damage to surrounding tissues and organs. SBRT is used to treat non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), and other types of cancer that have spread (metastasized). Many lung cancer patient groups receive SBRT. Instead of the conventional 20-33 visits, the patient receives 3-8 treatment fractions.
The Effectiveness of SBRT in Lung Cancer Patients’ Immune System
In a 2018 study published in the International Journal of Molecular Science, researchers performed an immunophenotyping analysis in blood samples from 7 patients with lung cancer, deemed unfit for surgery, treated with SBRT. Immunophenotyping is a process that uses antibodies to identify cells based on the types of antigens or markers on the surface of the cells. The objective of the study was to determine the effectiveness of SBRT on the patients’ immune systems. (Navarro-Martín, Arturo, et al.)
Immunophenotyping analysis was performed during SBRT treatment and up to 6 months after the final dose of SBRT. Among the findings of this study, most notably, SBRT showed an effect on systemic immune cell populations, which is a relevant finding for supporting future combinations of SBRT with immunotherapy for treating lung cancer patients. (Navarro-Martín, Arturo, et al.)
The Safety and Efficacy of Repeat SBRT
Another recent study, published in BMC’s Radiation Oncology Journal, evaluated the safety and efficacy of repeat SBRT for patients with repeat Stage I NSCLC and solitary lung metastasis, a single cancerous abnormality in the lung. Thirty-one patients with a repeated NSCLC or lung metastasis underwent repeat SBRT. All patients had grade 2 or lower radiation pneumonitis after the first SBRT. (Ogawa, Yasutaka, et al.)
After three years, the overall survival and local control rates of the patients were between 36%-53%. Furthermore, four patients showed no further recurrence of cancer for over five years after the second SBRT treatment. The study determined that repeat SBRT was safe, and local control and survival rates were higher than expected. The researchers concluded that SBRT should be an important treatment option for local recurrence of NSCLC or lung metastasis after previous local SBRT. (Ogawa, Yasutaka, et al.)
SBRT Clinical Trials at UCLA
The University of California, Los Angeles, has been conducting ground-breaking research in radiotherapy and SBRT as an effective modality to treat lung cancer. Currently, UCLA is beginning two clinical trials, implementing SBRT:
I. Phase II Study Evaluating Safety and Efficacy of Stereotactic Body Radiotherapy and Radiofrequency Ablation for Medically Inoperable and Recurrent Lung Tumors near Central Airways
This study will research the effect of SBRT, and radiofrequency ablation (RFA), for inoperable lung cancer near central airways. Radiofrequency ablation is a medical procedure in which part of the electrical conduction system of a tumor is removed using the heat generated from medium frequency alternating current. UCLA Department of Radiation Oncology hopes that by combining these 2 treatment options, they will achieve improved local control. Furthermore, they hope that this treatment course will be more effective and better tolerated than standard methods.
II. Randomized, Phase I/II Study of Ablative Radiotherapy +/- MEDI 4736 (Durvalumab) for Medically Inoperable Early-Stage Non-Small Cell Lung Cancer
Early-stage lung cancer is often treated with surgery. However, for patients who are not good candidates for surgery due to other medical conditions, SBRT is the standard treatment. While both surgery and SBRT are effective treatments, there is still the challenge of a recurrence of cancer elsewhere in the body.
This study will be conducted in two parts. The first part will enroll up to 15 patients and will examine whether combining SBRT with Durvalumab, an immunotherapy drug, is safe. The second phase of the study will enroll about 90 additional patients, to determine if radiation therapy or radiation therapy combined with Durvalumab is an effective treatment. Patients participating in the second part of the trial will either receive SBRT or SBRT and Durvalumab combined.
SABR Consortium and NHS
The SABR UK Consortium has provided a comprehensive guideline for clinics to implement SABR treatments. The guideline covers all the stages of the treatment process including:
- Imaging
- Contouring
- Treatment planning
- Verification
In June 2020, NHS England announced the acceleration of SABR, requiring radiotherapy departments to offer SABR treatments for non-small cell lung cancer and those with lung, lymph nodes, and non-spine bone oligometastatic disease. In the UK, patients are already benefiting from NHS England’s new SABR acceleration.
MVision’s Guideline-Compliant AI Segmentation, GCAIS™, SABR Model
MVision AI is the pioneer of guideline-compliant AI segmentation, GCAIS™, radiotherapy software. MVision supports the growing need for SABR. Within three months of the NHS’s SABR mandate, MVision developed the only lung CT, auto-segmentation model which follows the SABR Consortium guideline.
MVision’s deep learning system helps you automate organ-at-risk contouring, including lymph nodes, to streamline your cancer treatment planning. Robust, HIPAA, and GDPR compliant, MVision AI brings the highest quality radiotherapy planning SaaS solution for your oncology department.
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Sources
Navarro-Martín, Arturo, et al. “Preliminary Study of the Effect of Stereotactic Body Radiotherapy (SBRT) on the Immune System in Lung Cancer Patients Unfit for Surgery: Immunophenotyping Analysis.” International Journal of Molecular Sciences, vol. 19, no. 12, 2018, p. 3963. Crossref, doi:10.3390/ijms19123963.
Ogawa, Yasutaka, et al. “Repeat Stereotactic Body Radiotherapy (SBRT) for Local Recurrence of Non-Small Cell Lung Cancer and Lung Metastasis after First SBRT.” Radiation Oncology, vol. 13, no. 1, 2018. Crossref, doi:10.1186/s13014-018-1080-4.
UCLA Health. “Clinical Trial: Study Evaluating Treatment Course of a Short, Intense Radiation Therapy Followed by Radiofrequency Ablation for Medically Inoperable, Hard to Reach Lung Tumors.” UCLA, 2021, www.uclahealth.org/radonc/body.cfm?id=295.—.
UCLA Health. “Radiation With or Without Immunotherapy for Early-Stage (Stage I or II) Inoperable Lung Cancer – UCLA Radiation Oncology, Los Angeles, Santa Monica, CA.” UCLA Health, UCLA, 2021, www.uclahealth.org/radonc/radiation-with-or-without-immunotherapy-for-early-stage-stage-i-or-ii-inoperable-lung-cancer.
