Radiation Therapy

Overview

Radiation Therapy uses precisely targeted high-energy X-ray beams to destroy cancer cells by damaging their DNA and preventing them from dividing. It is one of the most effective and widely used cancer treatments, delivered by a linear accelerator in daily fractions over several weeks. Radiation therapy may be used as the primary curative treatment, combined with chemotherapy (chemoradiotherapy), given before surgery to shrink a tumour, after surgery to destroy residual cancer cells, or as a palliative treatment to relieve pain and symptoms in advanced cancer. Modern techniques including IMRT, VMAT, and stereotactic radiosurgery deliver high doses with millimetre precision while protecting surrounding healthy tissue.

Types of Radiation Therapy

• External Beam Radiotherapy (EBRT) — the most common form, delivered by a linear accelerator from outside the body
• Intensity Modulated Radiation Therapy (IMRT) — shapes the radiation beam precisely to match the tumour contour, sparing adjacent healthy structures
• Stereotactic Body Radiotherapy (SBRT) — delivers very high ablative doses in 1 to 5 fractions for small, well-defined tumours
• Brachytherapy — radioactive sources placed directly inside or immediately adjacent to the tumour for localised high-dose treatment
• Proton Beam Therapy — uses protons instead of X-rays to deposit dose precisely at the tumour with minimal exit dose beyond it

Risk Factors of Radiation Therapy

• Diagnosis of a solid malignant tumour in a location amenable to safe and effective external beam or stereotactic radiotherapy
• Post-operative residual disease or close surgical resection margins requiring adjuvant radiotherapy to reduce local recurrence risk
• Inoperable tumour due to location, size, or the patient's inability to tolerate major surgery
• Recurrent cancer at a previously treated site where re-irradiation with careful dose calculation is considered
• Palliative clinical indication for symptom control including bone pain, haemorrhage, airway obstruction, or spinal cord compression
• Concurrent chemotherapy requirement for radiosensitisation in tumour types where combined modality treatment improves outcomes

Symptoms of Radiation Therapy

• Skin redness, dryness, and peeling (radiation dermatitis) in the field of treatment emerging 2 to 3 weeks into the course
• Cumulative fatigue that builds progressively throughout the treatment course and may persist for weeks after completion
• Mucositis and difficulty swallowing in head and neck radiotherapy patients causing significant nutritional challenge
• Nausea and diarrhoea in patients receiving abdominal or pelvic radiotherapy affecting bowel function
• Urinary frequency, urgency, and dysuria in patients receiving pelvic radiotherapy for prostate or gynaecological cancers
• Hair loss limited to the treated area for patients receiving cranial or scalp radiotherapy
• Breathlessness and dry cough in thoracic radiotherapy patients from radiation pneumonitis
• Swelling and lymphoedema in the treated region from lymphatic disruption by radiation dose