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← Oncology and palliative care indexChapter sections
Purpose and principlesIndications, selection and cautionsAssessment before treatmentTreatment approachComplications, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Radiotherapy

Oncology and palliative care · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Purpose and principles

Explain curative and palliative radiotherapy, connect target definition and fractionation to tumour control and normal-tissue risk, and recognise urgent, acute and late radiation toxicity.

Radiotherapy aims to maximise tumour-control probability while constraining normal-tissue complication. External-beam planning uses simulation images and reproducible immobilisation to define visible tumour, subclinical-risk volumes and setup margins. Organs at risk are contoured and dose-volume constraints applied. Image guidance verifies position during treatment. Brachytherapy places a source close to or within the target and has separate procedural safety.

Fractionation exploits differences in repair, repopulation, redistribution and reoxygenation. Hypofractionation gives fewer larger fractions in evidence-based settings; conventional fractionation uses smaller repeated doses; stereotactic treatment delivers highly conformal ablative doses to selected small targets. Concurrent chemotherapy or radiosensitisers can improve control but increase acute and late toxicity.

Toxicity follows field, dose, fraction size, previous treatment and patient factors. Skin reaction, mucositis, oesophagitis, diarrhoea, urinary symptoms and fatigue are common acute patterns. Late effects include fibrosis, strictures, organ dysfunction, endocrine failure, cognitive change, fracture and second malignancy. New severe symptoms still require assessment for infection, thrombosis or cancer progression rather than automatic attribution to radiation.

Key points

  • Radiotherapy deposits ionising energy that damages DNA directly and through free radicals; fractionation allows normal-tissue repair while repeated exposure accumulates tumour effect.
  • Treatment may be definitive, neoadjuvant, adjuvant, consolidative or palliative and can use external beam, stereotactic techniques or brachytherapy.
  • CT simulation, immobilisation, target and organ-at-risk contouring, dose planning and independent checks precede the first fraction.
  • Dose and fractionation are tumour-, site- and intent-specific; use the current Royal College of Radiologists guidance and local protocol rather than memorised schedules.
  • Radiosensitivity, oxygenation, concurrent systemic treatment, previous irradiation and normal-tissue reserve affect both control and toxicity.
  • Acute effects occur in proliferating tissues during or soon after treatment; late fibrosis, vascular, neurological, endocrine and second-cancer effects can appear months or years later.
  • Palliative radiotherapy can rapidly relieve bone pain, bleeding, obstruction or neurological risk, but emergency corticosteroid, surgery or stabilisation may also be needed.
  • Pregnancy, implanted devices, transport burden and inability to reproduce position require early planning, not day-one improvisation.

Indications, selection and cautions

Curative local treatment

Definitive or perioperative radiation is selected when local control contributes meaningfully to cure or durable disease control.

Palliative indication

Painful bone metastasis, bleeding, compression or symptomatic local mass may improve with a shorter burden-sensitive course.

Acute field toxicity

Erythema, mucositis, odynophagia, diarrhoea or cystitis appears in irradiated tissues during treatment and shortly afterwards.

Late tissue injury

Fibrosis, vascular change, endocrine loss, neuropathy, fracture or organ dysfunction can develop long after the acute reaction resolves.

Radiation emergency contextRed flag

Cord compression, airway compromise or cerebral oedema requires urgent multidisciplinary rescue; radiotherapy planning must not delay immediate stabilisation.

Assessment before treatment

  1. 01
    Planning CT with immobilisationFirst step
    Why
    Create the reproducible geometry used for target and organ contouring.
    Interpretation and limitations
    Position, bladder or bowel preparation and contrast must match treatment needs; movement or anatomy change can invalidate the plan.
  2. 02
    MRI or PET image fusion
    Why
    Improve target definition where soft tissue or biological information changes contouring.
    Interpretation and limitations
    Registration error and treatment-position differences matter; fused images supplement rather than replace planning geometry.
  3. 03
    Dose-volume plan review
    Why
    Verify target coverage and normal-tissue constraints before treatment.
    Interpretation and limitations
    The radiation oncologist and physics team assess hotspots, organ doses, previous irradiation and technical deliverability through independent checks.
  4. 04
    On-treatment imaging
    Why
    Confirm anatomy and positioning during the course.
    Interpretation and limitations
    Image guidance detects setup error and anatomical change; major weight loss, tumour shrinkage or organ filling may require replanning.
  5. 05
    Toxicity and blood monitoring
    Why
    Detect field- and combination-specific adverse effects.

Treatment approach

01PlanDefine intent and geometryFirst stepRadiotherapy is proposed after diagnosis and staging.+
  1. 1Agree curative or palliative intent, alternatives and the evidence-based dose-fractionation option at MDT and consultation.
  2. 2Complete simulation, immobilisation and image fusion, then contour targets and organs at risk using tumour-specific standards.
  3. 3Perform physics optimisation and independent verification, including previous-dose review and pregnancy or device precautions before first exposure.
02DeliverMaintain safe reproducibilityThe approved plan enters treatment within the planned cancer pathway.+
  1. 1Verify identity, site, consent, setup and image guidance at each attendance, following correction thresholds before beam delivery.
  2. 2Review acute toxicity, nutrition, analgesia and concurrent medicines during the course, interrupting only when benefit-risk and recovery require it.

Complications, monitoring and follow-up

  • Review setup images and delivery records throughout treatment, investigating repeated shifts rather than normalising them.
  • Assess field-specific skin, mucosal, gastrointestinal, urinary, neurological and marrow effects at planned on-treatment reviews.
  • Track weight, hydration, pain and nutrition, arranging dietetic or feeding support before severe depletion interrupts curative therapy.
  • Document cumulative dose, fractionation, technique, field and organs at risk for lifelong access and any future re-irradiation.
  • At follow-up separate expected treatment evolution from recurrence and screen for site-specific late endocrine, vascular, skeletal and functional effects.

Special situations

Fraction is biological

The same total physical dose given in different fraction sizes can have different tumour and late-tissue effects.

Geometry is treatment

A technically perfect dose plan fails if the person cannot reproduce position or internal organs move outside the planned relationship.

Acute and late differ

Severe early mucosal reaction does not translate directly into every late effect, although field and combined treatment influence both.

Palliation can be short

Evidence-based shorter schedules reduce travel and treatment burden without implying that symptom relief is less active care.

Prior dose follows patients

Previous fields and organ doses constrain future surgery and radiotherapy even many years later.

Common pitfalls

  1. 01

    Using one fractionation schedule for every tumour.

  2. 02

    Treating planning CT as a diagnostic scan only.

  3. 03

    Ignoring weight or anatomy change during treatment.

  4. 04

    Attributing every new symptom to radiation.

  5. 05

    Losing prior field and dose records.

  6. 06

    Delaying emergency stabilisation for routine planning.

Practice

Two practice questions

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Question 1 of 2
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Oncology and palliative careOriginal SBA

Radiotherapy fractionation

Why can two radiotherapy courses with the same total physical dose produce different tumour control and late normal-tissue effects?

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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • Royal College of Radiologists radiotherapy fractionation guidanceEvidence-based dose and fractionation recommendations across curative and palliative indications.
  • NHS England cancer programmeNational radiotherapy pathways, specialist services and integration with multidisciplinary cancer care.
  • NICE shared decision making recommendationsCommunication of treatment intent, fractionation options, benefits and late harms.
  • Royal College of Pathologists cancer datasetsPathological diagnosis, margins and staging information that directs radiotherapy planning.
  • UKONS acute oncology initial management guidelinesRecognition and immediate management of acute oncological deterioration during treatment.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting review
Interpretation and limitations
Assess skin, mucosa, intake, bowel, bladder, marrow and organ function according to site and concurrent systemic treatment.
  • 3Replan when anatomy changes materially rather than continuing a geometrically invalid treatment for convenience.
    • 03FollowManage response and late effectsThe course completes or palliative benefit is being assessed.+
    1. 1Provide expected timing of acute peak and recovery, field-specific self-care and emergency symptoms such as dehydration or neurological decline.
    2. 2Assess response at the tumour-appropriate interval because early imaging can reflect inflammation rather than final control.
    3. 3Monitor late organ effects and rehabilitation needs, preserving prior field and dose information for future procedures or re-irradiation decisions.
    JurisdictionUnited Kingdom