Stereotactic Body Radiation Therapy — Targeted Radiotherapy

Stereotactic body radiation therapy uses sophisticated four-dimensional imaging and computerised targeting systems to deliver concentrated doses of ionising radiation to tumours in the body. Unlike traditional external beam radiotherapy, which delivers smaller daily doses across several weeks, SBRT administers ablative doses in typically one to five outpatient sessions. Customised immobilisation devices prevent patient movement during each session.

The delivery system continuously tracks tumour movement caused by natural physiological processes, such as respiration. By accounting for motion in real time, the treatment volume is tightly restricted to the tumour margin. This sharp dose fall-off minimises radiation toxicity to neighbouring healthy tissues, allowing safe administration of therapeutic radiation to critical anatomical sites.

SBRT provides an effective, tissue-preserving treatment option for individuals who may not be suitable candidates for conventional surgery due to underlying health conditions, advanced age, or challenging tumour locations. For patients facing early-stage malignancies or limited metastatic spread (oligometastases), SBRT can eradicate localised tumours with minimal physical downtime. Furthermore, because the entire treatment course concludes in just a few visits, it significantly reduces the logistical and emotional burden of frequent hospital appointments. Understanding SBRT helps patients participate actively in multidisciplinary care discussions regarding non-invasive alternatives to operative tumour resection.

Prior to SBRT, patients undergo high-resolution imaging, such as four-dimensional computed tomography (4D-CT), positron emission tomography (PET-CT), and magnetic resonance imaging (MRI). These scans map the precise contours and respiratory motion of the tumour. While SBRT itself does not rely on direct tumour biomarkers, tissue biopsies confirming histology and molecular testing (such as EGFR or KRAS mutations in lung cancer) remain critical for planning comprehensive systemic management alongside local ablative radiotherapy.

SBRT is most frequently utilised in early-stage non-small cell lung cancer, especially when operative surgery poses excessive risks. It is also standardly employed for primary liver malignancies such as hepatocellular carcinoma and localised prostate cancer. Additionally, SBRT plays an essential role in managing oligometastatic disease, where a primary cancer has spread to only a few isolated sites, particularly the lungs, liver, adrenal glands, or bony spine.

SBRT frequently serves as a definitive alternative to surgical resection for early-stage or medically inoperable tumours. In systemic disease, clinicians integrate SBRT alongside targeted therapies, immunotherapies, or chemotherapy to clear resistant or slow-progressing oligometastatic lesions. Because it delivers targeted energy, SBRT rarely causes systemic immunosuppression, allowing systemic treatments to proceed with minimal disruption. Treatment schedules require meticulous physics quality assurance and simulation sessions to ensure reproducible alignment.