Carcinoma of the tonsil is a type of squamous cell carcinoma. The tonsil is the most common site of squamous cell carcinoma in the oropharynx. It comprises 23.1% of all malignancies of the oropharynx. The tumors frequently present at advanced stages, and around 70% of patients present with metastasis to the cervical lymph nodes. . The most reported complaints include sore throat, otalgia or dysphagia. Some patients may complain of feeling the presence of a lump in the throat. Approximately 20% patients present with a node in the neck as the only symptom.
Main risk factors of developing carcinoma tonsil include tobacco smoking and regular intake of high amount of alcohol. It has also been linked to human papilloma virus (HPV type HPV16). Other risk factors include poor maintenance of oral hygiene, a genetic predisposition leading to inclination towards development of throat cancer, immunocompromised states (such as post solid-organ transplant), and chronic exposure to agents such as asbestos and perchloroethylene in certain occupations, radiation therapy and dietary factors.
Signs and symptoms
The early lesions are usually asymptomatic. The patients presenting with an advanced stage of the disease comprises around 66–77% of the cases.
The most important signs include a lump in the neck when palpated and weight loss. People may also present with fatigue as a symptom.
The primary tumor does not have readily discernible signs or symptoms as they grow within the tonsillar capsule. It is difficult to notice anything suspicious on examination of the tonsil other than slight enlargement or the development of firmness around the area. The carcinoma may occur in one or more sites deep within the tonsillar crypts. It may be accompanied by the enlargement of the tonsil. The affected tonsil grows into the oropharyngeal space making it noticeable by the patient in the form of a neck mass mostly in the jugulodigastric region. As the tonsils consist of a rich network of lymphatics, the carcinoma may metastasize to the neck lymph nodes which many are cystic. Extension of tumor to skull or mediastinum can occur.
The additional symptoms include a painful throat, dysphagia, otalgia (due to cranial nerve involvement), foreign body sensation, bleeding, fixation of tongue (infiltration of deep muscles) and trismus (if the pterygoid muscle is involved in the parapharyngeal space).
On the other hand, the tumor may also present as a deep red or white fungating wound growing outwards, breaking the skin surface with a central ulceration. This wound-like ulcer fails to heal (non-healing) leading to bleeding and throat pain and other associated symptoms.
During biopsy, the lesion may show three signs: gritty texture, firmness and cystification owing to keratinization, fibrosis and necrosis respectively.
Cervical lymphadenopathy may be present.
Cause
Smoking and alcohol abuse are the major risk factors. Viral causes have recently been taken under consideration as one of the risk factors. Viruses such as Epstein-Barr virus (EBV) (majorly involved in causing nasopharyngeal carcinoma) and human papilloma virus are included in this category. Chewing of betel nut (Areca catechu) quid has been directly associated to cause oral cancers. It has also been stated under the FDA poisonous plant data base by the U.S Food and Drug Administration An unbalanced diet, deficit in fruits and vegetables has shown to increase the risk of cancer.
Pathophysiology Direction of spread Structures involvedAlong Glossotonsillar sulcus Base of tongue Superior Soft palate or nasopharynx Laterally (Infiltrating through the constrictor muscle) Pharyngeal space, Pterygoid musculature, Mandible Superior spread through parapharyngeal space Base of skull Inferior Lateral neck Extensive spread in parapharyngeal space Carotid artery, Carotid sheath
Metastasis to regional lymphnodes is common as the tonsil has a rich supply of lymphatics giving way to the tumor cells to metastasis to other lymph nodes (commonly the lymph nodes of neck) and cause lymphadenopathy. The cervical lyphydenopathy can be ipsilateral (70% or more patients) or bilateral (30% and fewer patients). The carcinoma of tonsil usually spreads through the cervical lymph node levels II, III, IV, V, and retropharyngeal lymph nodes.
The fourth edition of WHO' s classification of head and neck tumors subdivides squamous cell carcinoma of the tonsil into two types: HPV positive or negative. HPV positive tumors arise from the deep lymphoid tissue of the tonsillar crypts and are non-keratinizing. On the other hand HPV negative tumors develop from the tonsillar surface epithelium and hence have keratinizing dysplasia.
Routes of metastasis Metastasis is common in tonsillar carcinoma. It largely depends on the stage of the cancer and the route through with the cancer cells metastasize. The cancer cells may spread to adjacent structures, to lymphatics or to distant locations in the body producing secondary tumors.
Local The tumor may spread locally to soft palate and pillars, base of tongue, pharyngeal wall and hypopharynx. It may invade pterygoid muscles and mandible, resulting in pain and trismus. Parapharyngeal space may also get invaded.
Lymphatic 50% of patients have initial cervical node involvement at the time of presentation. Jugulodigastric lymph nodes are the first to be involved.
Distant metastasis The occurrence of distant metastasis varies extensively, ranging between 4–31% in clinical studies. Factors influencing the incidence of distant metastasis are: Location of primary tumor Initial staging Histological differentiation Loco-regional control of the primary tumor
The records of 471 male patients with tonsillar carcinoma seen at the Veterans Administration Medical Center, Hines, Illinois, have been reviewed to establish the incidence and site of distant metastasis. All the patients were histological diagnosed and proven cases of tonsillar carcinoma. 72 (15%) out of 471 patients and 33 (29%) of 155 autopsied patients were reported to have distant metastasis.
Squamous cell carcinoma was the most common reported cell type (88%); cases with lymphoepithelioma had the highest incidence of distant metastasis. The most common anatomical sites of incidence of distant metastasis include lung, liver and bones. Thorough investigation of these organs is highly recommended before treatment as well as during follow-ups.
Diagnosis
The first step to diagnosing tonsil carcinoma is to obtain an accurate history from the patient. The physician will also examine the patient for any indicative physical signs. A few tests then, maybe conducted depending on the progress of the disease or if the doctor feels the need for. The tests include: Fine needle aspiration, blood tests, MRI, x-rays and PET scan.
Staging
The staging of a tumor mass is based on TNM staging.
T staging is the based on the tumor mass. The N staging is based on the extent of spread of cancer to the lymph nodes. Finally, the M stage indicates if the cancer has spread beyond the head and neck or not.
T Staging The basis of deciding the T stage depends on physical examination and imaging of the tumor. T Stage Tumor Dimension Tx Primary tumor cannot be assessed T0 Primary tumor cannot be located Tis Carcinoma in situ T1 ≤ 2 cm in dimension T2 > 2 cm but ≤ 4 cm in dimension T3 > 4 cm and has grown till the epiglottis T4a Moderately advanced, tumor has grown into larynx, beyond muscles of tongue, hard palate, lower jawbone and/or medial pterygoid muscles T4b Extremely advanced, invasion of lateral pterygoid muscle, pterygoid plates, nasopharynx, into skull base or is encasing the carotid artery.
N staging
This stage is decided through the assessment of the lymph nodes. N Stage Lymph node dimension Nx No assessment of neck lymph nodes N0 No evidence of spread N1 Ipsilateral, Single lymph node, ≤ 3 cm in size N2a cancer cells have metastasised to a single lymph node, ipsilateral to main tumor, > 3 cm but ≤ 6 cm in size N2b Cancer cells have metastasised to multiple lymph nodes, ipsilateral to mail tumor, > 6 cm in size N2c Detection of lymph nodes in the neck, contralateral or bilateral to the main tumor, >6 cm in size N3 Metastasis of cancer cells to one or more lymph nodes, >6 cm in size
M staging
Based on the examination of the entire body.
M Stage Metastasis beyond Head and neck M0 No evidence M1 Evidence of metastasis to structures outside head and neck present, commonly involved organs are: Lungs, bones, brain
Finally, the stage is decided by concluding the above results and referring the following chart:
Stage T Stage N Stage M Stage Stage I T1 N0 M0 Stage II T2 N0 M0 Stage III T3 N0 M0 T1 N1 M0 T2 N1 M0 T3 N1 M0 Stage IVA T4a N0 M0 T4a N1 M0 T1 N2 M0 T2 N2 M0 T3 N2 M0 T4a N2 M0 Stage IVB T4b Any N M0 Any T N3 M0 Stage IVC Any T Any N M1
Treatment
The treatment for tonsil carcinoma includes the following methods:
Radiotherapy
Early radio-sensitive tumors are treated by radiotherapy along with irradiation of cervical nodes. The radiation uses high-energy X-rays, electron beams, or radioactive isotopes to destroy cancer cells.
Chemotherapy
Induction chemotherapy is the treatment adapted for shrinking the tonsil tumor. It is given prior to other treatments, hence, the term induction. After the therapy is completed, the patient is asked to rest and is evaluated over a period of time. Then the patient is given chemo-radiation therapy (a combination of chemotherapy and radiation) to completely destroy the tumor cells.
Surgery
If radiation and chemotherapy are unable to destroy the tumor, surgical intervention is considered. Excision of the tonsil can be done for early superficial lesions. Large lesions and those which invade bone require wide surgical excision with hemimandibulectomy and neck dissection (Commando operation)
Combination therapy
Surgery may be combined with pre- or post operative radiation. Chemotherapy may be given as an adjunct to surgery or radiation.
Prognosis
Prognosis is determined by various factors such as stage, Human Papilloma Virus (HPV) status, Lymph infiltration of cancer cells, spread of cancer cells beyond the lymph node capsule, margins of the tumor and the extent of metastasis. Many factors are unique to each individual patient and may affect the chances of success of the treatment.
Factors determining the prognosis of tonsillar carcinoma are as follows:
HPV status Tonsillar carcinoma can be either HPV related or HPV unrelated. It is shown that cases which are HPV positive have a better prognosis than those with HPV negative oropharyngeal cancer.
Stage The stage at which the cancer presents itself affects the type of definitive treatment, chance of cure, recurrence of cancer and survival rate of the patient. Generally the patient presents very late due to the lack of definitive symptoms in the early stages of the disease. Nearly three fourths of the patients present in Stage III or later.
The stages of oropharyngeal cancer are as follows:
Stage 0 (carcinoma in situ): This stage indicates a good prognosis as most patients with stage 0 survive for a long period without the requirement of an intensive treatment. Although, the patient must cease smoking as it can increase the risk of developing a new cancer. Stage I and II: Most patients presenting at this stage receive successful treatment, showing a good prognosis. The modes of treatment for this stage include chemotherapy, surgery, radiation therapy or chemoradiation. The main treatment at this stage is radiation, targeting the tumor and the cervical lymph nodes. Surgical removal of the tumor and lymphadenectomy of the cervical (neck) lymph nodes can also be taken up at the main treatment method instead of radiation. Remaining cancer cells post surgery are treated with chemoradiation.