Glossary of Head & Neck Cancer Terms

Age-standardised rate (ASR)

A rate a population would have if it had a standard age structure, expressed per 100,000 people. ASRs let researchers compare cancer incidence between countries with different age distributions; a high ASR in a small country may represent very few actual cases.

AJCC staging

The American Joint Committee on Cancer TNM classification. The 8th edition introduced separate stage groups for HPV-mediated (p16-positive) oropharyngeal cancer and incorporated depth of invasion for oral cavity cancer.

Actinic cheilitis

Chronic ultraviolet damage to the lip vermilion, with dryness, scaling, fissuring and loss of the sharp lip border. It is a precancerous field change and the usual precursor of lower-lip squamous cell carcinoma.

See also: Lip cancer

Active surveillance

Deliberate monitoring of a low-risk cancer with serial imaging or examination, with treatment only if it progresses. It is an accepted option for selected small papillary thyroid microcarcinomas.

See also: Thyroid cancer

Adjuvant treatment

Treatment given after the main (usually surgical) treatment to reduce recurrence risk — typically radiotherapy or chemoradiotherapy based on margins, nodal disease and pathological risk features.

Areca nut

The seed of the areca palm, chewed alone or in betel quid. It is an IARC Group 1 carcinogen and a major cause of oral submucous fibrosis and oral cavity cancer in South Asia and the Pacific, even without added tobacco.

Basal cell carcinoma (BCC)

The commonest skin cancer; slow-growing, locally destructive but rarely metastasising. On the head and neck it is often treated with excision or Mohs surgery because of its proximity to the eye, nose and ear.

Bethesda System

A six-category reporting system for thyroid fine-needle aspiration cytology (I non-diagnostic to VI malignant), with an estimated malignancy risk and recommended management for each category.

Betel quid

A chew typically containing areca nut, betel leaf, lime and often tobacco, held against the cheek for long periods. It is the dominant exposure behind buccal mucosa cancer in South Asia.

Biomarker

A measurable biological feature used to guide diagnosis, prognosis or treatment — for example p16/HPV in oropharyngeal cancer, plasma EBV DNA in nasopharyngeal carcinoma, PD-L1 CPS for immunotherapy and thyroglobulin after thyroid cancer treatment.

Breslow depth

The thickness of a melanoma measured in millimetres from the top of the epidermis to the deepest tumour cell. It is the strongest predictor of melanoma stage and drives the width of excision and sentinel node biopsy decisions.

Chemoradiotherapy

Radiotherapy given at the same time as chemotherapy (most often cisplatin in head and neck cancer). The chemotherapy sensitises tumour cells to radiation and treats microscopic systemic disease, at the cost of added toxicity.

Cisplatin

A platinum chemotherapy drug used concurrently with radiotherapy for locally advanced head and neck cancer, commonly at 100 mg/m² every three weeks in guideline protocols. Kidney function, hearing and blood counts are monitored.

Cutaneous squamous cell carcinoma (cSCC)

A skin cancer arising from keratinocytes. On the ear, scalp, lip and temple it has a higher rate of perineural invasion and nodal spread than on the trunk or limbs.

De-escalation

Reducing treatment intensity — lower radiotherapy dose, fewer drugs — to limit long-term toxicity in favourable-prognosis disease such as HPV-positive oropharyngeal cancer. It remains investigational and should be done only in clinical trials.

Depth of invasion (DOI)

How far an oral cavity cancer has grown downward from the mucosal surface, measured in millimetres. In AJCC 8 it upstages the T category and guides the decision to perform an elective neck dissection.

DICOM

The standard file format for medical imaging. Sending full DICOM series from a CT, MRI or PET-CT is essential for a genuine second opinion; printed reports and JPEG screenshots are not enough for treatment planning.

Dysphagia

Difficulty swallowing. In head and neck cancer it can result from the tumour, surgery, radiotherapy fibrosis, stricture or nerve injury, and is assessed by a speech-language pathologist with swallowing studies.

EBV DNA

Epstein–Barr virus DNA measured in plasma. In nasopharyngeal carcinoma, a high pre-treatment level indicates higher risk, clearance after treatment suggests response, and a rising level during follow-up can precede visible recurrence.

EBER

Epstein–Barr virus-encoded small RNA detected by in-situ hybridisation in tumour tissue, used to confirm EBV-associated nasopharyngeal or sinonasal lymphoepithelial carcinoma.

Erythroplakia

A velvety red patch of oral mucosa that cannot be attributed to another condition. It carries a substantially higher malignant-transformation risk than homogeneous leukoplakia and usually requires biopsy and excision.

Extranodal extension (ENE)

Cancer growing through the capsule of a lymph node into surrounding tissue. It is a high-risk pathological feature that generally indicates postoperative concurrent chemoradiotherapy rather than radiotherapy alone.

Field cancerisation

The concept that the whole upper aerodigestive mucosa has been exposed to the same carcinogens, so a patient cured of one tobacco-related cancer remains at risk of a new, separate primary tumour.

Fine-needle aspiration (FNA)

A thin needle used to sample cells from a neck lump or thyroid nodule. It is the correct first tissue test for a suspicious cervical node; open excisional biopsy as a first step is avoided.

Free flap

Tissue (skin, muscle, bone or bowel) transferred from a donor site with its blood vessels reconnected by microsurgery to vessels in the neck. Used to reconstruct the tongue, jaw, cheek or pharynx after cancer resection.

GLOBOCAN

The International Agency for Research on Cancer database of cancer incidence, mortality and prevalence estimates for 185 countries. The 2022 edition is the primary source of the statistics on this site.

HPV (human papillomavirus)

A common virus; persistent infection with high-risk types, especially HPV-16, causes most oropharyngeal cancers in North America and Northern Europe. HPV status is assessed by p16 immunohistochemistry with HPV DNA/RNA confirmation when needed.

HPV vaccination

Vaccination against high-risk HPV types, ideally before exposure (routinely at age 11–12 with national catch-up schedules). The 9-valent vaccine covers HPV-16 and is expected to reduce future HPV-positive oropharyngeal cancer incidence.

Hypopharynx

The lowest part of the throat, including the pyriform sinus, postcricoid region and posterior pharyngeal wall, that channels food around the larynx into the oesophagus.

IMRT

Intensity-modulated radiotherapy: computer-shaped beams that conform a high dose to the tumour while sparing salivary glands, mandible, spinal cord and swallowing structures. A curative course is typically about 33 fractions over 6–7 weeks.

Immunotherapy

Treatment that releases the immune system’s brakes, most often PD-1 inhibitors such as pembrolizumab or nivolumab. Used mainly for recurrent/metastatic head and neck squamous cell carcinoma and advanced melanoma; side effects are autoimmune-like inflammation.

Induction chemotherapy

Chemotherapy given before the main local treatment, for example gemcitabine + cisplatin before chemoradiotherapy in locally advanced nasopharyngeal carcinoma, or TPF in selected larynx-preservation protocols.

Leukoplakia

A white oral patch that cannot be scraped off and cannot be diagnosed as another condition. It is an oral potentially malignant disorder; risk is higher for non-homogeneous, speckled, red-mixed or dysplastic lesions.

Lymphoedema

Swelling from impaired lymphatic drainage after neck dissection or radiotherapy, which can involve the face, neck, tongue or submental region and affect speech, swallowing and appearance.

Mohs surgery

A layered excision technique with immediate microscopic margin examination that maximises tissue preservation. Commonly used for basal cell and squamous cell cancers of the eyelid, nose, lip and ear.

Mucositis

Inflammation and ulceration of the mouth and throat lining caused by radiotherapy or chemotherapy. It typically peaks in weeks 3–6 and requires analgesia, rinses, antifungal review and nutritional support.

Nasopharynx

The upper part of the throat behind the nose. Tumours here are usually EBV-associated, highly radiosensitive and often present with a neck lump or unilateral middle-ear effusion.

Neck dissection

Surgical removal of cervical lymph node groups, classified as elective/sentinel, selective, modified radical or radical depending on which levels and non-lymphatic structures are removed.

NCCN

The US National Comprehensive Cancer Network, which publishes regularly updated, evidence-based treatment guidelines. NCCN guidance underpins much of the work-up, treatment and follow-up content on this site.

Odynophagia

Painful swallowing, a common symptom of oropharyngeal, hypopharyngeal and laryngeal tumours and of radiation mucositis.

Oral submucous fibrosis

A chronic scarring condition caused mainly by areca nut chewing, with burning, stiffness and progressive limitation of mouth opening. It is an oral potentially malignant disorder requiring cessation and surveillance.

Oropharynx

The middle part of the throat including the palatine tonsils, base of tongue, soft palate and pharyngeal walls. In high-income countries most cancers here are now HPV-associated.

Otalgia (referred)

Ear pain with a normal ear examination, caused by shared nerve pathways from the throat, tongue base or larynx. It is a classic warning sign of an occult head and neck tumour.

Overdiagnosis

Detection of a cancer that would never have caused symptoms or death. It is the main explanation for the steep rise in thyroid cancer incidence in South Korea and other high-income countries.

p16

A protein used as a surrogate immunohistochemical marker of HPV-driven oropharyngeal cancer. p16 testing is recommended for all oropharyngeal squamous cell carcinomas and determines the AJCC 8 stage group.

PD-L1 CPS

Combined positive score: the proportion of PD-L1-staining tumour and immune cells relative to viable tumour cells, multiplied by 100. It is used to guide first-line pembrolizumab use in recurrent/metastatic head and neck cancer.

Perineural invasion

Tumour tracking along a nerve sheath. On the head and neck it can cause numbness, pain or facial weakness and usually requires wider excision, contrast MRI and adjuvant radiotherapy.

Pleomorphic adenoma

The commonest benign salivary gland tumour, usually in the parotid. It is removed by formal parotidectomy with facial nerve preservation rather than simple enucleation, because incomplete removal causes difficult multifocal recurrence.

Proton therapy

Radiotherapy using charged particles that deposit most of their energy at a controllable depth. Considered for skull-base, sinonasal and re-irradiation cases, but availability and cost vary widely.

Salvage surgery

An operation performed to remove cancer that persists or recurs after radiotherapy or chemoradiotherapy. In nasopharyngeal carcinoma it may involve endoscopic skull-base resection.

Second primary tumour

A new, separate cancer arising after a first one, rather than a recurrence. Common in the upper aerodigestive tract of continuing smokers because of field cancerisation.

Sentinel lymph node biopsy

Removal and examination of the first one or two draining lymph nodes to detect microscopic spread, used in selected early oral cavity cancers and melanomas to avoid a full neck dissection.

Stoma

A surgically created opening of the trachea onto the neck after total laryngectomy. It is permanent, and breathing and smelling occur through it rather than the nose and mouth.

TNM

The staging shorthand for primary Tumour extent, regional Node involvement and distant Metastasis. Stage groups differ by subsite and, for oropharyngeal cancer, by HPV status.

TORS

Transoral robotic surgery: a minimally invasive approach through the mouth used to resect selected tonsil and base-of-tongue tumours and to find an occult primary in the tongue base.

Tracheoesophageal puncture

A small channel created between the trachea and oesophagus after total laryngectomy so a voice prosthesis can produce speech when the stoma is covered.

Trismus

Reduced mouth opening caused by fibrosis of the muscles of mastication after surgery or radiotherapy. Daily stretching exercises started early are the main preventive measure.

Tumour board

A multidisciplinary meeting of head and neck surgeons, radiation and medical oncologists, radiologists, pathologists, dentists, dietitians and speech therapists that agrees stage and treatment intent before therapy begins.

Xerostomia

Dry mouth from reduced salivary flow, a common long-term effect of radiotherapy to the head and neck. It raises lifetime dental decay risk and requires daily fluoride and regular dental review.