What are the common metastasis sites for tonsillar (tonsil) cancer?

From the Guidelines

Tonsillar cancer most commonly metastasizes to the cervical lymph nodes, particularly levels II and III of the neck. When tonsillar cancer spreads, it typically follows a predictable pattern, with ipsilateral (same side) lymph node involvement occurring first, followed by contralateral (opposite side) spread in advanced cases. The rich lymphatic drainage of the tonsil region explains this pattern of metastasis. Distant metastasis is less common but can occur to the lungs, liver, and bones in advanced disease.

Key Points to Consider

• Early detection of cervical lymph node involvement is crucial for proper staging and treatment planning, as the presence and extent of lymph node involvement significantly impacts prognosis and treatment decisions, with more extensive nodal disease generally indicating a poorer prognosis and necessitating more aggressive treatment approaches 1.
• Patients with tonsillar cancer should undergo comprehensive neck examination and imaging (CT, MRI, or PET scans) to assess for lymph node metastasis.
• A cystic neck mass can be a sign of metastasis, and up to 62% of neck metastases from Waldeyer ring sites (tonsils, nasopharynx, and base of tongue) are cystic 1.
• The incidence of cancer in a cystic neck mass increases to 80% in patients >40 years old, and the proportion of cystic neck masses that are malignant will continue to rise as the incidence of HPV-positive oropharyngeal HNSCC continues to increase 1.

Important Factors in Evaluation

• Age >40 years is associated with a greater risk of HNSCC, particularly in patients with non-HPV related disease 1.
• Tobacco and alcohol use are synergistic risk factors for HNSCC 1.
• Symptoms such as pharyngitis, dysphagia, otalgia, and unexplained weight loss may indicate a malignancy 1.
• A nontender neck mass is less likely to be infection or inflammation and more likely to be neoplastic 1.

From the Research

Tonsillar Cancer Metastasis Site

• The most common sites for cervical lymph node metastasis in tonsillar cancer are levels II and III, which contain the deep jugular chain 2.
• The rate of contralateral occult metastasis is around 28.6% 3.
• Factors associated with contralateral nodal metastasis include T3-4 stages, primary lesions close to the midline, or ipsilateral multilevel involvement 3.
• Ipsilateral multilevel involvement is an independent factor for contralateral metastasis 3.
• Retropharyngeal lymph node (RPLN) metastasis is confirmed in around 26.5% of cases and is associated with poor disease-specific survival 3.
• Positive pre-operative image, posterior pharyngeal wall invasion, more than N2 stage, contralateral node metastasis, or ipsilateral multilevel involvement are correlated with RPLN metastasis 3.

Diagnostic Methods

• Computed tomography (CT) and magnetic resonance imaging (MRI) are common imaging methods to detect cervical lymph node metastasis of head and neck cancer 4.
• CT has a higher sensitivity than MRI when node is considered as unit of analysis, while MRI has a higher specificity than CT when neck level is considered as unit of analysis 4.
• The minimal axial diameter of 10 mm could be considered as the best size criterion for MRI, compared to 12 mm for CT 4.
• Positron emission tomography/computed tomography (PET-CT) has demonstrated potential for assessing head and neck squamous cell carcinoma (HNSCC) and detecting cervical lymph node metastases 5.
• PET-CT exhibits the highest diagnostic performance, with a sensitivity of 74.5% and specificity of 83.6% at the patient level 5.