Radiation Therapy — Procedure Guide, Recovery & Risks | MyMedicPlus

Radiation therapy (radiotherapy) uses high-energy ionising radiation to damage cancer cell DNA, preventing replication and causing tumour cell death. Delivery modes include external beam radiotherapy (EBRT) using linear accelerators delivering IMRT, VMAT, or SBRT, and brachytherapy using radioactive sources placed inside or adjacent to the tumour.

Radiation therapy is used with curative intent for localised prostate, breast, cervical, head and neck, lung, and brain cancers, either alone or combined with surgery and chemotherapy. Palliative radiotherapy relieves pain from bone metastases, spinal cord compression, brain metastases, and airway or oesophageal obstruction.

Treatment planning begins with CT simulation and tumour volume delineation. IMRT delivers dose from multiple angles with intensity modulation to sculpt dose around critical structures. VMAT delivers continuous arc therapy in a single rotation. SBRT delivers large doses in 1–5 fractions. Brachytherapy places sealed radioactive sources (iridium-192 for HDR, iodine-125 for LDR) within or adjacent to the tumour.

Acute side effects (fatigue, skin erythema, mucositis, dysphagia depending on site) peak at week 3–4 and resolve within 2–6 weeks of treatment completion. Patients are reviewed weekly during treatment. Late effects (fibrosis, lymphoedema, hormonal changes) may emerge months to years later and require long-term follow-up.

Acute side effects vary by site: mucositis and xerostomia (head and neck), radiation pneumonitis (lung), enteritis (abdomen/pelvis), and cystitis (prostate). Late effects include fibrosis, secondary malignancy (0.5–1% lifetime risk), neurocognitive changes (brain), lymphoedema, and bowel dysfunction. IMRT significantly reduces late toxicity versus conventional radiotherapy.

Curative radiotherapy achieves 5-year local control of 80–90% for early-stage prostate cancer, 85–95% for early laryngeal cancer, and 60–80% for localised non-small cell lung cancer treated with SBRT. Palliative radiotherapy provides meaningful pain relief in 60–80% of patients with bone metastases within 4 weeks.