Monday, October 7, 2013

Tonsillar Cancer

Introduction

The tonsils are made of lymphoid tissue, which contains cells of the immune system that are involved in fighting infection. The palatine tonsils are what we commonly refer to as "the tonsil;" however, there is also a patch of lymphoid tissue at the base of tongue, called the lingual tonsil. Other lymphoid tissue occurs in the nasopharynx (high in the pharynx behind the nasal passages) and this is referred to as the adenoid. Together, the palatine tonsils, the lingual tonsil and the adenoid make up a ring of lymphoid tissue in the pharynx - Waldeyer's ring.

The most common cancers that occur in the tonsils are squamous cell carcinoma (SCCA). Lymphoma can also occur in the tonsil. The cancers that occur in the tonsil are similar to those that occur elsewhere in Waldeyer's ring. Lymphoepithelioma is an older term for a non-keratinizing undifferentiated SCCA.

Risk Factors

The risk factors for SCCA are smoking, drinking and in particular the combination of heavy smoking with heavy drinking. More recently viral infection has been implicated in the etiology of SCCA in the upper aerodigestive tract. Human papilloma virus (HPV) DNA has been found in SCCA of the tonsil. However, we do not know what role HPV plays in the development of cancer at this location. Risk factors notwithstanding, there are individuals who develop SCCA in the tonsil (and at other sites in the upper aerodigestive tract) without having any of the known risk factors. Currently, we have limited understanding of what factors may lead to development of SCCA of the tonsil in individuals who neither smoke nor drink. It may be that DNA viruses such as HPV may play a role in the process of carcinogenesis in these individuals.

Signs and Symptoms

Most tonsilar cancers are relatively quiet until they become very large or ulcerate. Most often, the first presenting symptom is that of a neck mass. Many tonsilar cancers have early spread to lymph nodes in the neck (cervical metastasis) and this is a common presenting feature of these cancers. The cervical metastases tend to be cystic and can be confused with a benign neck lump called a branchial cleft cyst. Because of the lack of symptoms in tonsilar SCCA, tonsilar asymmetry (one tonsil being larger than the other) in an adult is sufficient reason to perform a tonsillectomy to rule out cancer. In addition, if SCCA is diagnosed in the neck and the site of origin is not identified, a tonsillectomy is usually performed to rule out the tonsil as the source of the cancer. Fortunately, tonsilar SCCA does not have a high rate of early spread to distant sites such as the lung.

Staging

Tonsilar SCCA is staged according to size of the tumor and degree of involvement of bone and deep muscles. It is also important to evaluate the neck for metastatic spread of SCCA, which tends to occur rather early in the course of the disease. Distant spread is relatively infrequent and, in most cases, can be ruled out with a simple chest X-ray. In cases where there is extensive or bilateral neck disease a CT scan of the chest or a whole body PET scan may be obtained.

Treatment

Options for treatment depend on size of the tumor, whether adjacent structures (tongue, palate, bone) are involved, and degree of neck spread. Surgery followed by radiation therapy is the form of treatment that offers the best chance of cure. Surgery can sometimes be done through the mouth (transorally) as one would do a tonsillectomy in a child; however, this approach can only be done for the smaller tumors. Larger tumors usually require a different approach by splitting the mandible (mandibulotomy and mandible swing) or by entering the pharynx laterally (lateral pharyngotomy). A neck dissection with removal of lymph nodes structures is almost always performed because of the high rate of early tumor spread to the neck. Patients who have mandibulotomy or pharyngotomy as the approach for tumor removal require a temporary tracheostomy tube which in general stays in place for 4-14 days.

Combination chemotherapy and radiation therapy (chemoradiation) has also been used for these tumors. In these cases, neck dissection is performed afterward for any patient that initially presented with palpable neck disease. Combination chemoradiation is still in its early stages and we do not have complete information on tumor control with this modality, although the early results suggest cure rates that are comparable to those obtained with surgery. For smaller tumors, the results with surgery, both in terms of tumor control and functional outcome, are better with surgery followed by postoperative radiotherapy. The decision to choose one form of treatment over another has to be individualized. Factors that influence the choice of treatment are the size and location of the tumor, the experience of the treating team (surgeon, radiation oncologist, and medical oncologist), and the preference of the patient and his/her family.

Rehabilitation

Tumors of the tonsil, like most tumors of the upper aerodigestive tract, can affect speech and swallowing functions. The treatment of these tumors, whether it is surgery or radiation or chemotherapy, can also interfere with normal speech and swallowing. The process of rehabilitation involves prevention of complications and early intervention to maximize functional outcome. Dental care is quite important as is nutrition, swallowing ability and adequate social support.

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