Radiotherapy — Procedure Guide, Recovery & Risks | MyMedicPlus

Radiotherapy (radiation therapy) uses precisely targeted high-energy ionising radiation to damage the DNA of cancer cells, impairing their ability to replicate and triggering programmed cell death (apoptosis). It is one of the three pillars of curative cancer treatment alongside surgery and systemic therapy (chemotherapy, targeted therapy, immunotherapy), and over 50% of all cancer patients receive radiotherapy at some point during their treatment.

Radiotherapy is delivered through two principal modalities. External beam radiotherapy (EBRT) uses a linear accelerator (LINAC) to generate high-energy photon (X-ray) beams that are directed at the tumour from multiple angles outside the body. Modern EBRT techniques include intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic body radiotherapy (SBRT) — each offering progressively more conformal dose distributions that maximise dose to the tumour while sparing critical adjacent structures. Brachytherapy delivers radiation internally by placing sealed radioactive sources (iridium-192 for high-dose rate, iodine-125 or palladium-103 for low-dose rate) directly within or immediately adjacent to the tumour, achieving very high localised doses with rapid dose fall-off in surrounding tissue.

Radiotherapy is used with curative intent as definitive treatment, as adjuvant therapy after surgery to reduce local recurrence, as neo-adjuvant therapy before surgery to downsize tumours, or as palliative treatment to relieve symptoms. Modern treatment planning uses CT, MRI, and PET-CT simulation to precisely define tumour volumes and deliver individualised treatment.

Radiotherapy is indicated across a broad spectrum of malignancies and clinical scenarios, either as the primary treatment modality or as part of a multimodal treatment strategy.

Curative intent — radiotherapy as definitive treatment: Radiotherapy alone achieves cure in localised early-stage head and neck cancers (laryngeal, pharyngeal, oral cavity), early-stage non-small cell lung cancer (stereotactic body radiotherapy, SBRT), prostate cancer (EBRT or brachytherapy), cervical cancer (chemoradiation), early Hodgkin lymphoma, medulloblastoma and other paediatric brain tumours, and localised bladder cancer in organ-preservation protocols.

Adjuvant radiotherapy after surgery: Post-operative radiotherapy reduces local recurrence risk in breast cancer (after lumpectomy), rectal cancer, head and neck cancer with positive margins or extracapsular nodal extension, brain tumours (glioblastoma, ependymoma), and soft tissue sarcoma with close margins.

Neo-adjuvant radiotherapy before surgery: Pre-operative chemoradiotherapy for rectal cancer and oesophageal cancer achieves tumour downstaging, converting some initially unresectable tumours to resectable and improving pathological complete response rates.

Concurrent chemoradiotherapy: Combined chemotherapy and radiotherapy (chemoradiation) achieves superior results to radiotherapy alone for cervical cancer (cisplatin), head and neck squamous cell carcinoma (cisplatin), non-small cell lung cancer, and glioblastoma.

Palliative radiotherapy: Short-course palliative radiotherapy (1–10 fractions) provides symptom relief for bone metastases (pain control in 80% of patients), spinal cord compression (motor function preservation), brain metastases (single or whole-brain), and obstruction of airway, oesophagus, or bronchus.

Contraindications: Absolute contraindications include pregnancy (particularly in the first trimester for abdominal/pelvic fields) and prior maximum-dose radiotherapy to the same field. Relative contraindications include active systemic lupus erythematosus (enhanced radiosensitivity) and pacemakers or cochlear implants within the treatment field requiring specialist assessment.

Radiotherapy planning and delivery follows a structured, multi-step pathway involving radiation oncologists, medical physicists, dosimetrists, and therapeutic radiographers.

Step 1 — CT simulation and imaging: The patient is positioned in a reproducible immobilisation device — thermoplastic mask for head and neck or CNS, knee and ankle support for pelvis, wing board for breast. A planning CT scan is acquired in this exact position with fiducial markers or tattoo reference points placed on the skin. MRI and PET-CT are often co-registered with the planning CT for superior tumour delineation.

Step 2 — Target volume delineation: The radiation oncologist contours the gross tumour volume (GTV — visible tumour on imaging), clinical target volume (CTV — GTV plus suspected microscopic extension), and planning target volume (PTV — CTV plus margins for patient set-up uncertainty). Critical organs at risk (OAR) — spinal cord, brainstem, optic nerves, parotid glands, kidneys, lungs, bowel — are also contoured to protect from excessive dose.

Step 3 — Dose planning: Medical physicists and dosimetrists use treatment planning software to design a plan that delivers the prescribed dose (e.g., 60–70 Gy in 30–35 fractions for radical head and neck cancer; 45 Gy in 25 fractions for adjuvant breast) to the PTV while keeping OAR doses below established tolerance limits. IMRT and VMAT techniques use multiple beams with varying intensity and arc delivery to sculpt highly conformal dose distributions.

Step 4 — Quality assurance and verification: All treatment plans undergo independent physicists' review and patient-specific quality assurance measurements using phantom dosimetry. Before the first fraction, image-guided radiotherapy (IGRT) using daily cone-beam CT or kilovoltage X-rays verifies patient positioning and confirms the tumour is in the planned position before beam delivery.

Step 5 — Treatment delivery: The patient lies on the LINAC treatment couch in their immobilisation device. Therapeutic radiographers position the patient, perform daily imaging verification, and deliver the fraction — typically 5–30 minutes including set-up and imaging time. Treatment is delivered Monday to Friday, with doses of 1.8–2 Gy per fraction (conventional fractionation) or 2.5–8 Gy per fraction (hypofractionation or SBRT).

Step 6 — Weekly review: Patients are reviewed weekly by the radiation oncology team throughout treatment for toxicity assessment, supportive care, and treatment modification if needed.

Radiotherapy achieves curative outcomes across many cancer types and provides meaningful symptom relief in the palliative setting.

Prostate cancer: EBRT (IMRT/VMAT) achieves 10-year biochemical control rates exceeding 85% for low-risk, 75% for intermediate-risk, and 55–65% for high-risk localised prostate cancer in combination with androgen deprivation therapy.

Early laryngeal cancer: Definitive radiotherapy for T1–T2 glottic carcinoma achieves local control rates of 85–95% and preserves laryngeal function in the majority of patients.

Cervical cancer: Concurrent cisplatin chemoradiotherapy with intracavitary brachytherapy achieves 5-year overall survival of 65–80% for locally advanced cervical cancer.

Breast cancer: Adjuvant whole-breast radiotherapy after breast-conserving surgery reduces ipsilateral breast tumour recurrence from approximately 20–25% to under 7% at 10 years and provides a modest but significant improvement in breast cancer mortality.

Non-small cell lung cancer: SBRT for stage I NSCLC achieves 3-year local control of 85–95% — superior to conventional surgery-equivalent outcomes in medically inoperable patients.

Bone metastases: Palliative radiotherapy provides significant pain relief in 60–80% of patients within 4–8 weeks. A single 8 Gy fraction achieves equivalent palliation to multi-fraction regimens for uncomplicated bone metastases, with less patient inconvenience.

Reduction in radiotherapy-related toxicity: Modern IMRT reduces rates of xerostomia (dry mouth) in head and neck cancer from 50–60% (conventional radiotherapy) to under 20%, representing a major advance in quality of life for long-term survivors.

Radiotherapy side effects are divided into acute (occurring during and up to 3 months after treatment) and late effects (emerging after 3 months and persisting long-term).

Acute side effects (site-dependent): - Fatigue: Universal, present in 70–90% of patients receiving any radiotherapy - Skin reactions: Erythema, dry or moist desquamation (breast, head and neck skin fields) - Mucositis: Painful oral mucosal ulceration (head and neck cancer) — peak severity at weeks 3–4 - Xerostomia: Dry mouth from parotid gland irradiation in head and neck treatment - Dysphagia: From oesophageal, pharyngeal, or hypopharyngeal mucosal reaction - Nausea and vomiting: Abdominal or pelvic fields, craniospinal irradiation - Diarrhoea: Pelvic fields (prostate, cervical, rectal cancer) - Radiation cystitis: Urinary frequency and dysuria during pelvic radiotherapy

Late effects (site-dependent, months to years): - Fibrosis: Subcutaneous and lung fibrosis (breast, lung treatments) - Xerostomia: Permanent dry mouth if major salivary glands are in the treatment field without IMRT protection - Lymphoedema: Arm or leg oedema from nodal irradiation - Bowel dysfunction: Chronic diarrhoea, bleeding, or stricture from pelvic treatment - Hormonal changes: Hypothyroidism (thyroid in field), premature menopause (pelvic fields) - Second malignancy: Less than 1% lifetime risk from scatter radiation — substantially lower than older techniques - Radiation necrosis: Osteoradionecrosis of jaw (head and neck), brain necrosis (brain tumours) — uncommon with modern IMRT

Acute side effects typically peak 2–3 weeks into treatment and in the 2–4 weeks after treatment completion, before gradually resolving over the following 4–6 weeks. Long-term recovery is treatment-site specific.

During treatment — supportive care: Patients are reviewed weekly by the radiation oncology team throughout the treatment course. Dietitian support is provided for patients with head and neck or oesophageal cancer experiencing dysphagia or significant weight loss. Prophylactic PEG (gastrostomy) feeding tube insertion is considered for patients expected to have severe swallowing dysfunction. Mouth rinses, antifungal therapy, and analgesics manage mucositis. Anti-diarrhoeal agents and dietary modification support pelvic radiotherapy patients.

After treatment (weeks 1–8): Fatigue typically peaks at 1–2 weeks post-treatment and improves gradually. Skin reactions continue to evolve for 1–2 weeks after the last fraction before healing begins. Head and neck patients experience the most challenging recovery, with mucositis, xerostomia, and dysphagia potentially persisting for several weeks to months. Gradual resumption of oral diet is guided by symptom response.

First surveillance imaging (week 8–12): Most patients have their first post-treatment tumour response assessment at 8–12 weeks — using CT, PET-CT, MRI, or tumour marker measurement depending on the cancer type. Complete metabolic response on PET-CT is a strong predictor of durable disease control.

Long-term follow-up: Ongoing surveillance for cancer recurrence and late treatment effects continues for 5–10 years in most cancer protocols. Annual late-effects assessments by specialist nurses or allied health teams monitor xerostomia, fibrosis, lymphoedema, bowel and bladder function, hormonal status, and bone health, with referral to sub-specialists as needed.