Skip to textbook content
Doctor’s PassportTextbook
TopicsAll topics

Loading topic navigation…

Textbook navigation
TopicsAll topics

Loading topic navigation…
Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Anal cancer

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

RapidFull
!
Perianal sepsis, obstruction or major bleeding

Systemic toxicity from an abscess or fistula, necrotising infection, uncontrolled tumour haemorrhage, severe treatment enterocolitis or rare complete obstruction requires urgent resuscitation and source control.

Action: Use ABCDE care, provide analgesia, fluids, blood products and broad-spectrum antibiotics when infection is possible and obtain urgent colorectal, acute-oncology and radiology input for drainage or diversion that preserves later oncological options; do not delay sepsis treatment while obtaining cancer staging.

Synopsis

Recognise anal canal and margin cancer without attributing persistent symptoms to haemorrhoids, obtain sphincter-preserving tissue and site-specific staging and deliver definitive chemoradiation, delayed response assessment and salvage or metastatic care.

  • Most anal canal cancers are HPV-associated squamous-cell carcinomas and are biologically and therapeutically distinct from low rectal adenocarcinoma.
  • Persistent bleeding, pain, ulcer, lump, discharge, pruritus or continence change requires inspection, digital rectal examination and inguinal-node palpation; haemorrhoids do not close the differential.
  • The diagnostic reference standard is adequate biopsy, often during examination under anaesthesia, while preserving sphincter anatomy and avoiding an uncontrolled excision that compromises later treatment.
  • Stage with high-resolution MRI pelvis and contrast CT chest and abdomen; PET-CT is useful for nodal clarification and radiotherapy planning but does not replace biopsy of a decisive atypical lesion.
  • Sample a suspicious inguinal node by ultrasound-guided FNA or core because confirmation changes stage and the radiation field.
  • Test HIV status with consent and assess other immunosuppression and anogenital HPV disease; effective antiretroviral therapy continues through cancer treatment with interaction review.
  • First-line curative treatment for most non-metastatic anal canal SCC is definitive chemoradiotherapy with mitomycin and fluoropyrimidine, preserving the anus and sphincters.
  • A small well-differentiated anal-margin cancer that can be excised with adequate margins without sphincter damage may undergo local excision; this exception should not be applied to typical canal disease.
  • Tumour regression can continue for approximately 6 months after chemoradiation. A shrinking residual lesion without progression is observed through the protocol response window rather than biopsied or operated on prematurely.
  • Persistent or recurrent local cancer is confirmed with biopsy and considered for salvage abdominoperineal excision in a specialist pelvic cancer centre.
  • Metastatic treatment commonly begins with carboplatin–paclitaxel in a fit patient, with later immune or other systemic options chosen from current approvals and prior treatment.
  • Proactive skin, bowel, urinary, analgesic, nutritional and sexual support helps patients complete uninterrupted radiotherapy and reduces avoidable late dysfunction.
  • HPV vaccination and cervical and other anogenital screening prevent related disease but do not replace assessment of a current anal symptom.

    • Key red flags

    Persistent anal bleeding, pain, ulcer, lump, discharge, pruritus or change in continence requires digital and visual examination even when haemorrhoids are known.

    A hard irregular anal lesion, sphincter fixation, vaginal or prostatic involvement or a firm inguinal node suggests invasive or regional disease.

    Fever, escalating perianal pain, spreading erythema, crepitus or immunosuppression raises abscess or necrotising infection requiring immediate surgery and antibiotics.

    Severe diarrhoea, abdominal pain, dehydration, fever or cytopenia during chemoradiation requires assessment for treatment toxicity, infection and neutropenic enterocolitis.

    New leg oedema, pelvic pain, urinary obstruction or neurological symptoms after treatment may indicate nodal or pelvic recurrence.

    Persistent or enlarging tumour after an adequate post-chemoradiation observation period requires biopsy and salvage assessment, but early treatment inflammation alone is not failure.

    Perianal sepsis

    Fever, fluctuance, spreading erythema or crepitus requires immediate antibiotics and colorectal source control before detailed elective staging.

    Treatment toxicity

    Moist desquamation, uncontrolled diarrhoea, fever, urinary pain, dehydration or cytopenic symptoms during chemoradiation requires same-day oncology assessment.

    Investigation priorities

    01
    First-line anorectal and inguinal examinationFirst stepFirst line

    Define site, size, fixation, sphincter relation, vaginal or prostate involvement and regional nodes before biopsy.

    Management branches

    Persistent symptomExamine before attributing to benign disease

    Anal bleeding, pain, lump, discharge, pruritus or continence change persists or recurs.

    1. Inspect perianal skin, perform digital rectal examination, proctoscopy and bilateral groin examination and assess sepsis, immune suppression and HPV-related history.
    2. Arrange urgent colorectal assessment and biopsy under local or general anaesthesia, using drainage and antibiotics first when uncontrolled abscess or necrotising infection is present.
    3. Once histology is known, obtain pelvic MRI, CT and selective PET-CT and node sampling and discuss in the anal-cancer MDT.

    Key medicines

    Mitomycin and capecitabine with radiotherapyA common UK radical protocol gives mitomycin 12 mg/m² intravenously on radiotherapy day 1, maximum 20 mg, plus capecitabine 825 mg/m² orally twice daily on each radiotherapy treatment day; use the exact centre protocol.Confirm DPD status and monitor marrow, renal function, infection, diarrhoea, mucositis, hand–foot syndrome and haemolytic–uraemic toxicity; review antiretroviral and anticoagulant interactions and stop capecitabine for significant early toxicity.
    Carboplatin and paclitaxel for advanced diseaseA common 28-day regimen gives carboplatin AUC 5 intravenously on day 1 and paclitaxel 80 mg/m² intravenously on days 1, 8 and 15 for up to six cycles, modified for marrow, neuropathy and response.Monitor hypersensitivity, neutropenia, infection, thrombocytopenia, neuropathy, alopecia and organ function and review interactions and prophylaxis in HIV or other immune suppression.
    Open full textbook →Answer 2 questions
    Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
    Sources

    Sources and review status

    National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

    • ESMO anal cancer clinical practice guidelineDiagnosis, staging, definitive chemoradiation, response and salvage treatment.
    • ACPGBI anal cancer guidelineUK multidisciplinary assessment, imaging, treatment and surveillance.
    • NICE NG12 lower-GI cancer referralPersistent lower-GI symptoms and urgent suspected-cancer referral.
    • BNF capecitabineDPD status, dosing, interactions and fluoropyrimidine toxicity management.

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

    Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom