Cancers of the tonsil tend to be superficial, better differentiated, and of an earlier stage than other oropharyngeal tumors. The treatment of early tonsillar neoplasms (stages I and II) is usually radiation therapy alone. Transoral wide local excision of small, superficial lesions may be locally effective, but does not address the high potential of occult lymph node metastasis. Deeply invasive cancers require extensive resections of the pharyngeal wall or mandible.
Radiation for early cancers offers the advantage of treating upper-echelon lymph nodes. Treatment is usually unilateral unless extension to the tongue base or midline soft palate is present that warrants treatment of contralateral lymphatics. Ipsilateral treatment portals allow sparing of the contralateral mucosa and salivary glands. Because much of the tumor may be hidden from external beam photons by the mandible, deeper dose calculation with electron beam therapy is used, which can be combined with a small interstitial implant if invasion of adjacent tongue is present. Early cancers of the tonsillar pillar are less effectively treated with radiation alone than are cancers confined to the tonsillar fossa.
Radical radiotherapy to lymph nodes controls approximately 90% of limited nodal disease (N1) if the primary tumor is controlled, but nodal failure increases to more than 20% if failure occurs at the primary tumor site. Overall 5-year survival rates for patients with advanced primary tumors or regional metastases are generally less than 25% with single-modality therapy. Combinations of surgery and radiation therapy offer improved rates of local and regional tumor control, which, in some studies, has translated into improved survival. Similar tumor-control and survival rates have been reported for stage III (T3N0) patients without nodal metastases who are treated with radiation alone or combined surgery and radiation or surgery alone (
Table 90-9). In general, preoperative or postoperative radiation for advanced (stage III or IV) cancers of the tonsillar fossa is recommended, combined with resection to include the tonsillar fossa and regional nodes. In some instances, advances in surgical approaches may allow for sparing of the mandible, but composite resection of the pharynx, mandible, and neck remains a frequent surgical approach. Postoperative rather than preoperative radiation is currently preferred because it allows more accurate assessment of surgical margins, local extent of disease, and degree of lymphatic involvement, and is associated with lower rates of surgical complications.
Revision date: July 5, 2011
Last revised: by Amalia K. Gagarina, M.S., R.D.