Oropharyngeal Cancer
The oropharynx is the middle section of the throat, located behind the mouth, and includes the base of tongue, the tonsils and the middle third of the swallowing tract known as the pharynx. The pharynx is a tubular structure that starts at the back of the nose and ends at the top of the esophagus and voice box (larynx). The physiology of the pharynx is highly complex due to the fact that it is a common passageway for both food and air. The coordination of swallowing requires that food is directed through this common channel to make its way to the esophagus without entering the trachea and the lungs.
Risk factors for oropharyngeal cancer include smoking, chewing tobacco, heavy alcohol use, chewing betel nut, a diet low in fruits and vegetables, and being infected with the human papilloma virus (HPV). The majority of oropharyngeal cancers are squamous cell carcinoma, which originate in the lining of the throat. The next most common type of cancer arises from the minor salivary glands, which are located underneath the mucosal lining of the pharynx.
A variety of symptoms may be reported in patients with oropharyngeal cancer which include a sore throat that does not go away, difficulty swallowing, ear pain, unexplained weight loss, a foreign body sensation in the back of the throat and a change in voice. An unexplained lump in the neck can also be a sign of metastatic oropharyngeal cancer.
Diagnosis of a new oropharyngeal cancer starts with a detailed history of present illness, assessment of potential risk factors and a physical examination (examination of the neck for swollen lymph nodes, visual examination of the oropharynx including palpation of the base of the tongue and a fiberoptic examination of the throat). Imaging (CT with contrast or MRI) of the throat and neck from the base of the skull to the clavicles is an important part of assessing the extent of the tumor. Recently, PET/CT imaging has become an important part of the workup of a newly diagnosed oropharyngeal cancer. This whole body scan is an extremely sensitive method of looking for disease that has spread to the lymph nodes of the neck or to the rest of the body. Finally, an examination under anesthesia with directed biopsies is necessary for mapping out the extent of the tumor and for establishing a tissue diagnosis.
Prognosis is determined based on the stage and grade of the tumor, the location of the tumor, and whether the tumor is HPV-positive. Studies have shown that prognosis is better in HPV-associated oropharyngeal carcinoma by correlating HPV positivity with lower recurrence rates, plus longer overall and disease-free survival.
Treatment options: The oropharynx is an area within the throat that traditionally required a complicated surgical approach. Surgical access to this area was difficult, requiring a lip splitting incision and a bone cut through the lower jaw in order to move the lower jaw out of the surgical field. This radical approach required a tracheotomy for airway protection and a feeding tube for nutrition.
Open surgery was the standard of care for cancer of the oropharynx until the early 1990s, when the era of organ preservation emerged from advances in application of external beam radiation therapy and chemotherapy. It became clear that the oncologic and functional outcomes in patients treated with primary radiation and chemotherapy were equal to or better than the outcomes that resulted from open surgical treatment. Chemoradiation has been the standard treatment for oropharynx squamous cell carcinoma for the last 20 plus years.
In recent years, minimally invasive surgical approaches to the oropharynx have been developed in an attempt to provide a safe, effective and less morbid alternative to chemoradiation. Transoral laser microsurgery (TLM) and Transoral Robotic surgery (TORS) are the two important treatment options.
In 2009, the FDA cleared the da Vinci surgical system for TORS for benign lesions and early malignancies of the throat (oropharynx, hypopharynx and larynx). Since 2010, there has been a rapid expansion in the number of cancer centers that have incorporated TORS into their treatment algorithm for head and neck cancer. Mount Sinai Beth Israel is currently one of only a handful of facilities offering this state-of-the-art procedure.
The role of TORS in the management of oropharynx cancer is rapidly evolving. The current approach is to surgically remove the primary tumor and lymph nodes in the neck either simultaneously or in a staged fashion (less than three weeks after the TORS procedure). The information provided by pathologic analysis of the lymph nodes is extremely important in determining the role of and need for postoperative external beam radiation therapy with or without chemotherapy.
When oropharynx cancer is treated and recurs, the standard approach is an open salvage surgery. This most commonly involves a lip-splitting incision, bone cut in the lower jaw and wide extirpation of the disease. The defect created by removal of the tumor is most commonly reconstructed with regional or free tissue in order to rebuild the lining of the throat and restore bulk to the base of tongue.
Intra-operative radiation therapy (IORT) is a unique application of radiation therapy used in the setting of recurrent oropharynx cancer that boosts the oropharynx with radiation in a safe, effective and controlled setting.