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Head and neck cancer · Clinically reviewed

Floor of mouth cancer, red flags, staging - and modern UK treatment.

A squamous cell carcinoma under the tongue, closely linked to smoking, alcohol and paan. Caught early it is highly treatable - the three-week rule matters.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, NCCN and specialist head and neck oncology sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including transoral surgery, adjuvant chemo-radiotherapy and pembrolizumab.

Key facts

Floor of mouth cancer at a glance.

The essentials, in plain English - what it is, who gets it and how it is treated in the UK today.

  • What it is

    A squamous cell carcinoma of the oral cavity arising in the floor of mouth - the horseshoe of tissue beneath the tongue.

  • How common

    Around 2,000 UK cases a year and rising. It is the second most common subsite in the oral cavity.

  • Who gets it

    Men roughly twice as often as women historically, though the female rate is rising. Peak age 55 to 75.

  • Main risk factors

    Smoking and tobacco of any form, alcohol, betel or paan chewing, poor oral hygiene and HPV in a subset.

  • Cardinal red flag

    A non-healing mouth ulcer of more than three weeks - urgent two-week-wait head and neck cancer referral.

  • Treatment

    Transoral surgery with neck dissection for early disease, and surgery plus chemo-radiotherapy for locally advanced disease.

Why this guide matters

Early detection is the single biggest lever.

Survival in floor of mouth cancer is closely tied to stage at diagnosis. The three points below shape everything else on this page.

  • The three-week rule

    Any mouth ulcer, red or white patch or lump that has not settled in three weeks needs urgent two-week-wait referral under NICE NG12.

  • Modifiable risk matters

    Smoking, alcohol and paan account for most cases. Quitting genuinely changes outcomes - before, during and after treatment.

  • Specialist centres save lives

    Care is delivered through specialist head and neck cancer MDTs at commissioned centres, with reconstruction, oncology, dental and rehabilitation on one team.

How the diagnosis is made

From first symptom to an MDT plan.

The steps a UK GP, dentist or head and neck team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and risk factors

    Duration of symptoms, tobacco and alcohol use, betel or paan chewing, previous head and neck cancer and immunosuppression.

  2. 02

    Assessing

    Full oral and neck examination

    Visual inspection and bimanual palpation of the floor of mouth, tongue mobility, submandibular glands and cervical lymph nodes.

  3. 03

    Assessing

    Two-week-wait referral

    Any non-healing ulcer over three weeks, red or white patch, tooth mobility or unexplained neck lump goes on the NICE NG12 pathway.

  4. 04

    Confirming

    Flexible nasoendoscopy

    Specialist ENT examination of the upper aerodigestive tract to rule out a second synchronous primary. See our guide to flexible nasoendoscopy.

  5. 05

    Confirming

    Biopsy and specialist pathology

    An incisional or punch biopsy under local anaesthetic, reviewed by a specialist head and neck pathologist.

  6. 06

    Confirming

    Imaging and staging

    MRI of the primary, CT neck and chest and often PET-CT to complete TNM staging. Specialist commissioned in most units.

  7. 07

    Planning

    Dental clearance and MDT plan

    Restorative dentistry review before treatment and a specialist head and neck MDT decision at a commissioned centre.

Typical pathway: two-week-wait referral to MDT decision in a matter of weeks.

Symptoms

What floor of mouth cancer looks and feels like.

Symptoms often start small - a painless ulcer, a subtle patch or a lump under the tongue. The features below are the ones that should never be ignored.

  • Non-healing ulcer

    A painless ulcer under the tongue that has not settled in three weeks is the classic presentation.

  • Lump or induration

    A firm swelling or hardened area on the floor of mouth, often felt more than seen.

  • Red or white patch

    Erythroplakia and leukoplakia are premalignant. Any persistent patch warrants specialist review.

  • Neck lump

    Enlarged lymph nodes at level Ib or II in the neck can be the first sign - never ignore an unexplained neck lump.

  • Dysphagia and speech change

    Difficulty swallowing or altered speech as the tumour restricts tongue movement. See our guide to dysphagia.

  • Referred ear pain

    Otalgia with a normal-looking ear can be a warning sign in oral cancer. See our guide to ear pain.

  • Tooth mobility and denture change

    Loose teeth without dental cause, or dentures that suddenly stop fitting, deserve urgent review.

  • Red flag - three-week rule

    Any oral ulcer, patch or lump lasting over three weeks needs an urgent two-week-wait referral under NICE NG12.

Treatment

How floor of mouth cancer is treated in the UK.

Transoral surgery and neck dissection for early disease. Surgery with adjuvant chemo-radiotherapy for locally advanced disease. Immunotherapy for recurrent or metastatic disease.

  • Transoral surgery

    Wide local excision through the mouth, often with selective neck dissection, is the mainstay for early T1 to T2 N0 disease.

  • Selective neck dissection

    Removal of level I to III lymph nodes to stage the neck and clear microscopic disease, done at the same time as the primary resection.

  • Reconstruction with free flaps

    Radial forearm, anterolateral thigh or fibula free flaps restore function and appearance after larger resections.

  • Adjuvant chemo-radiotherapy

    Concurrent cisplatin and radiotherapy for high-risk features - positive margins, extranodal extension or advanced stage.

  • Definitive chemo-radiotherapy

    An organ-preserving alternative to surgery in selected locally advanced cases, delivered at specialist commissioned centres.

  • Immunotherapy

    Pembrolizumab (Keynote-048 and adjuvant Keynote-689) and nivolumab for recurrent or metastatic disease. See our checkpoint clinic.

  • Targeted therapy

    Cetuximab, an anti-EGFR antibody, used in selected patients unfit for platinum chemotherapy.

  • Rehabilitation and support

    Speech and language therapy, dietetics with PEG feeding, dental prostheses, lymphoedema care and psychological support.

What this guide is based on

The sources behind every claim on this page.

UK national guidance, international oncology standards and specialist society statements, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, dentist or head and neck team knows your history and can tell you which parts of this guide apply to you. If in doubt, get seen.

  • NICE. Suspected cancer: recognition and referral (NG12).

  • NICE. Cancer of the upper aerodigestive tract: assessment and management in people aged 16 and over (NG36).

  • NCCN. Clinical Practice Guidelines - Head and Neck Cancers.

  • Royal College of Surgeons and BAHNO. Head and neck cancer standards.

  • Cancer Research UK. Mouth and oropharyngeal cancer statistics.

  • MHRA and NHS England. Specialist commissioning for head and neck cancer.

Red flags

When mouth symptoms need urgent action.

Most mouth ulcers are benign and settle in a fortnight. These are the features that should not be watched and waited on.

  • Ulcer lasting over three weeks

    Any non-healing mouth ulcer beyond three weeks is a two-week-wait red flag - do not wait to see if it settles.

  • Persistent red or white patch

    Erythroplakia and leukoplakia are premalignant. Persistent patches warrant biopsy under specialist care.

  • Unexplained neck lump

    A firm, persistent cervical lymph node in an adult with risk factors needs urgent head and neck imaging and referral.

  • Unexplained tooth mobility

    Loose teeth without periodontal disease may reflect underlying bone or soft-tissue invasion.

  • Referred otalgia with a normal ear

    Persistent ear pain with a normal otoscopic examination in a smoker or drinker is a well-recognised warning sign.

  • Dysphagia or odynophagia

    Progressive swallowing difficulty or pain on swallowing needs urgent assessment - see our guide to dysphagia.

  • Weight loss and cachexia

    Unexplained weight loss with oral symptoms points to advanced disease and demands urgent staging.

  • Bleeding from the mouth

    Spontaneous oral bleeding, particularly from an ulcer or mass, is a late but urgent feature.

  • Second primary risk

    Patients with previous head and neck cancer have a lifelong risk of a second aerodigestive primary - regular surveillance matters.

Living with it

A serious diagnosis, with a real path forward.

Four things that make the biggest difference during and after treatment - stopping smoking, cutting alcohol, protecting speech and swallow, and staying in follow-up.

A quiet reminder

Rehabilitation is treatment, not an add-on.

Speech and language therapy, dietetics, dental rehabilitation and lymphoedema care are all part of getting back to daily life. Charities like the Mouth Cancer Foundation and Macmillan help too.

  1. 01 Stop

    Smoking cessation is non-negotiable

    Continued smoking during and after treatment worsens response, healing and survival. Free NHS support is available and works.

  2. 02 Alcohol

    Cut down or stop drinking

    Alcohol multiplies the effect of tobacco on the mouth. Reducing intake also protects healing tissue after radiotherapy.

  3. 03 Function

    Speech, swallow and nutrition

    Speech and language therapy, dietetics and PEG feeding keep function and weight steady through and after treatment.

  4. 04 Follow-up

    Long-term surveillance matters

    Regular MDT follow-up catches recurrence and second primaries early. Bring any new oral or neck symptom forward.

Frequently asked

Everything patients ask about floor of mouth cancer.

Straight answers on red flags, staging, surgery, chemo-radiotherapy and immunotherapy.

  • What is floor of mouth cancer?

    A squamous cell carcinoma arising in the horseshoe-shaped area of tissue beneath the tongue. It is a subsite of oral cavity cancer and is closely linked to smoking, alcohol and betel or paan use. See our head and neck cancer overview for the wider context.

  • What are the main warning signs?

    A non-healing ulcer, a persistent red or white patch, a lump or hardened area under the tongue, unexplained neck lump, loose teeth, referred ear pain, dysphagia or altered speech. Any of these lasting more than three weeks needs an urgent two-week-wait referral under NICE NG12.

  • How is it diagnosed?

    With a full oral and neck examination, flexible nasoendoscopy by ENT, a biopsy reviewed by a specialist head and neck pathologist, and imaging with MRI, CT of the neck and chest and often PET-CT. All patients are discussed at a specialist head and neck MDT.

  • How is early disease treated?

    For T1 and T2 N0 tumours, transoral wide local excision with selective neck dissection is the standard of care. Adjuvant radiotherapy is added selectively based on pathology, and reconstruction is planned with a specialist plastic surgery team when needed.

  • What about locally advanced disease?

    Larger or node-positive tumours are treated with surgery and adjuvant concurrent chemo-radiotherapy, usually cisplatin-based, or with definitive chemo-radiotherapy as an organ-preserving alternative. Complex reconstructions with free flaps are common.

  • Where does immunotherapy fit in?

    Pembrolizumab is used in first-line recurrent or metastatic disease based on Keynote-048, and the adjuvant Keynote-689 regimen was approved in 2024. Nivolumab is used after platinum failure. All are delivered through specialist commissioned services - see our checkpoint clinic guide.

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