Head and Neck Malignancies

Introduction

Head and neck cancers are the sixth most common group of malignancies worldwide. In the United States, the estimated incidence is 65,000 new cases per year, which are most commonly diagnosed among adults older than 50 years of age.

Geographic variations in the incidence and mortality rates of head and neck cancers are related to differences in patterns of exposure and behavior. Well-known risk factors include tobacco and alcohol consumption, betel chewing, and infection with high-risk human papillomavirus (HPV), specifically types 16 and 18, and Epstein–Barr virus (EBV).

Head and neck tumors can arise in the oral cavity, nasopharynx, hypopharynx, oropharynx, nasal cavity and paranasal sinuses, larynx, and salivary glands. Multiple histologies can be found in these sites, but more than 90% are squamous cell carcinomas (SCC). SCC is associated with aggressive behavior and high incidence of locoregional recurrence.

Several studies have reported an upward trend in the incidence of oropharyngeal cancer (OPC) worldwide. In the United States, HPV-related OPCs have risen since 1984. The most affected population are younger men with a history of multiple lifetime oral sex partners and without a long history of tobacco and alcohol consumption. Clinical presentation differs from the classic stereotype and is characterized by small tumors with bulky lymph nodal disease at diagnosis.

Evaluation of the Patient with Head and Neck Cancer

Patients diagnosed with head and neck cancers require a comprehensive evaluation by a multidisciplinary team consisting of head and neck surgeons, medical oncologists, radiation oncologists, plastic and reconstructive surgeons, dental surgeons, and speech pathologists.

Medical History

A complete medical history is collected, noting the onset and progression of symptoms and focusing on key risk factors that include tobacco and alcohol consumption, sun and environmental exposure, prior cancer history, number of sexual partners, immunosuppression, and other comorbidities. Family history and social circumstances are also recorded, as birthplace, ethnicity, and family support can play a role in treatment planning and rehabilitation. The rapid progression of symptoms suggests aggressive disease and may be an indication for emergency intervention.

Head and neck malignancies can have a major impact on patient´s activities of daily living, such as eating, speaking, swallowing, and breathing, which can affect performance status. Performance status is critical for assessing a patient’s ability to tolerate treatment. A complete pretreatment assessment should include an evaluation of nutritional and dental status, focusing on the need for supplemental nutrition (orally or using a gastrostomy tube), eradication of periodontal disease, or dental extraction.

Clinical Examination

A comprehensive head and neck examination should be performed to address the primary tumor site and to search for second primaries, which can be present in 2%–5% of patients. ^, Examination should be performed with the patient sitting upright and begins with the evaluation of the skin of the scalp, face, and neck, followed by palpation of the thyroid, parotid gland, neck nodal basins, and abnormal masses. Testing of cranial nerve function should be included routinely, as well as rhinoscopy and external ear examination. The examination of the oral cavity should include observation of mucosal lesions, dental care, and palpation of the tongue, floor of mouth, base of tongue, and tonsils.

Endoscopic assessment can be done with a mirror or with a flexible fiberoptic endoscopy, which will include visualization of the nasal cavity, nasopharynx, oropharynx, hypopharynx, and larynx. Functional tests should be done to evaluate vocal cord mobility.

Imaging Examination

Modern imaging has dramatically enhanced diagnosis and staging of head and neck cancers. Different modalities include ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). Modality selection is affected by multiple factors, including availability, coverage, experienced radiologists, primary location of the tumor, and stage of the disease.

US is useful for the assessment of superficial or soft-tissue lesions located in the thyroid or parotid gland, it is sensitive for the detection of lymph node metastasis, but it is operator-dependent and requires expertise. CT is widely available, allows rapid image acquisition, and reduces artifacts related to respiration and swallowing; it is best suited for defining primary tumor and identifying bone invasion, and can be used for guiding tissue biopsy. MRI offers a superior soft tissue contrast and is preferred when the tumor needs to be differentiated from adjacent soft tissue structures, including tumors arising in the sinonasal region, oral cavity, and salivary glands. PET/CT is frequently used to evaluate advanced head and neck cancers, regional and distant metastases, and post treatment response to chemoradiotherapy.

Biopsy

Tissue confirmation of the diagnosis is necessary before any cancer treatment; samples can be obtained using fine needle aspiration, core needle, or surgical biopsy. Care must be taken to obtain representative tissue samples that allow accurate histological classification.

Staging

Correctly staging the disease is an essential component of the oncologic evaluation. It allows a universal understanding of the disease and influences decision making. The tumor–node–metastasis (TNM) staging system, developed by the American Joint Committee on Cancer (AJCC), is the most commonly used staging system. Information needed to stage patients is obtained from physical examinations, laboratory tests, imaging exams, pathology results, and surgical reports. T stage is based on the anatomic location and size of the primary tumor. N indicates regional disease and considers the number and location of regional lymph nodes. M indicates the presence of distant metastasis. These are translated to an overall stage classification ranging from I to IV. Early-stage disease includes stages I and II, and advanced stage disease stages III and IV.

The recent eighth edition of the AJCC staging manual introduces significant changes to the head and neck section. The most significant updates are the creation of a separate staging classification for HPV-related OPC, the addition of depth of invasion (DOI) in the T category for oral cavity carcinoma, the incorporation of skin cancer staging (other than melanoma and Merkel cell carcinoma) in the head and neck chapter, the change in the T and N status in nasopharyngeal cancers, and the inclusion of the extranodal extension feature to the N category.

The T0 classification is used when the primary tumor is not known. More than 90% of unknown primary tumors are HPV- or EBV-positive, which is why T0 is only used for HPV-related OPCs and tumors located in the nasopharynx. T0 is not used for HPV-negative OPCs and other non-HPV-related cancers located in the oral cavity, larynx, hypopharynx, and paranasal sinus.

In this chapter, we will address staging by anatomical site, excluding tumors arising from the thyroid gland.

Oral Cavity

The oral cavity extends from the skin vermilion junction of the lips to the junction of the hard and soft palates superiorly, the circumvallate papillae inferiorly, and the anterior tonsillar pillars laterally. Different subsites in the oral cavity include the lips, alveolar ridge, buccal mucosa, retromolar trigone, hard palate, floor of mouth, and two-thirds of the anterior tongue. Table 23.1 summarizes the T stages for primary tumors of the oral cavity.

TABLE 23.1

T Stage for Primary Tumors of the Oral Cavity

From Amin MB, Edge S, Greene F, et al, eds. AJCC Cancer Staging Manual . 8th edn. New York: Springer International/American Joint Commission on Cancer; 2017.

T Category	T Criteria
Tis	Carcinoma in situ
T1	Tumor ≤2 cm with DOI ≤5 mm
T2	Tumor ≤2 cm with DOI >5 mm or tumor >2 cm but ≤4 cm with DOI ≤10 mm
T3	Tumor >2 cm and ≤4 cm with DOI >10 mm or tumor >4 cm with DOI ≤10 mm
T4a	Moderately advanced local disease Tumor >4 cm with DOI >10 mm or tumor invades adjacent structures only (e.g., through cortical bone of the mandible or maxilla, or involves the maxillary sinus or skin of the face) ^a
T4b	Very advanced local disease Tumor invades masticator space, pterygoid plates, or skull base and/or encases the internal carotid artery

a Superficial erosion of bone/tooth socket (alone) by a gingival primary is not sufficient to classify a tumor as T4.

The main change in oral cavity clinical and pathological staging was the inclusion of DOI based on the results of a large international collaborative study of oral cavity cancer. This study showed that DOI was significantly associated with disease-specific survival, supporting the relevance of this feature as a mark of biological behavior.

Clinical determination of DOI is challenging and requires the clinician to distinguish between a thick, exophytic tumor from one that is ulcerated and infiltrative; this information is used in conjunction with radiological features to plan treatment.

Of note, pathological DOI should be measured from the level of the basal membrane of the closest adjacent mucosa to the deepest point of tumor invasion.

Nasopharynx

The nasopharynx represents a transitional area between the nasal cavity and the oropharynx. It includes the vault, the lateral walls (formed by the orifices of the Eustachian tube superiorly and the superior constrictor inferiorly), the posterior wall, and the superior surface of the soft palate. Table 23.2 summarizes the T stages for primary tumors of the nasopharynx.

TABLE 23.2

T Stage for Primary Tumors of the Nasopharynx

Used with permission of the American College of Surgeons, Chicago, Illinois. The original source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017) published by Springer International Publishing.

T Category	T Criteria
T0	No tumor identified, but EBV-positive cervical node(s) involvement
Tis	Carcinoma in situ
T1	Tumor confined to the nasopharynx or extension to the oropharynx and/or nasal cavity without parapharyngeal involvement
T2	Tumor with extension to parapharyngeal space and/or adjacent soft tissue involvement (medial pterygoid, lateral pterygoid, prevertebral muscles)
T3	Tumor with infiltration of bony structures at skull base, cervical vertebra, pterygoid structures, and/or paranasal sinuses
T4	Tumor with intracranial extension, involvement of cranial nerves, hypopharynx, orbit, parotid gland, and/or extensive soft tissue infiltration beyond the lateral surface of the lateral pterygoid muscle

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