The oropharynx is the part of the throat that lies just behind the oral cavity and in the back of the mouth. The tonsil, tongue-base and soft palate are the most well-known areas of this region of the throat, which can only be visualized using special endoscopes or mirrors.
In 2014, an estimated 44,000 patients were estimated to be diagnosed with oral and pharyngeal cancer. More than 90% of oropharyngeal cancers are squamous cell carcinomas—so called because the tumors arise from the thin, flat “squamous” cells that cover the lining of the throat.
In the past, tumors arising in the oropharynx were uncommon and associated with heavy tobacco use. Over the past decade, there has been a dramatic change in the epidemiology of oropharyngeal cancer (OPC). A striking association has been made between oropharyngeal cancer and prior infection with the human papillomavirus (HPV).
Using the Surveillance, Epidemiology, and End Results (SEER) repository, investigators have shown that from 1988 to 2004, the incidence of HPV-positive oropharyngeal cancers increased by 225 percent. (doi = 10.1200/JCO.2011.36.4596)
Patients with OPC related to HPV tend to present earlier in life as compared to those with tobacco-associated OPC. The primary tumor is often difficult to see, hidden within the folds of the throat (tongue-base and tonsil.)
As a result, OPC cases typically are not diagnosed until the tumor metastasizes to the neck.
Numerous questions—about how to identify this disease earlier, how to prevent it, and which individuals are at greatest risk—continue to challenge researchers in the field. Yet, one thing is clear: multidisciplinary teams must transform therapy to keep pace with this “new” disease. Given these sweeping changes in the epidemiology of head and neck cancer, and in particular, the precipitous rise in HPV associated OPC, improvements in screening, prevention, and treatment must be made quickly.
Diagnosis and Clinical Evaluation
An essential part of the diagnosis and evaluation of oropharyngeal cancer is a thorough history and physical examination by a head and neck specialist. Symptoms relating to swallowing, breathing, and overall health are surveyed. A comprehensive survey is made of the patient’s past medical problems, treatment, habits and family history.
Head and neck specialists can directly examine the throat and oropharynx for signs of the primary tumor and its extent. This examination can be done through the mouth with an angled dental mirror and headlight or through the nose with a flexible fiberoptic endoscope.
Although the tumor may arise within the throat, nearly 80% of all patients with oropharyngeal cancer present with some kind of spread to the lymph nodes of the neck. Therefore, the neck is examined for signs of enlarged or abnormal lymph nodes.
After the physical examination, imaging is often obtained to more fully evaluate the extent of the tumor. A variety of imaging studies can be used: CT scan (or CAT scan), MRI (magnetic resonance imaging) or a PET scan (positron emission tomography.
A biopsy is necessary to confirm the suspected diagnosis. Sometimes, a piece of the tumor can be taken through the mouth in the office under only local anesthesia and minimal discomfort. Other times, a brief surgical procedure is required called an exam under anesthesia or direct laryngoscopy or pharyngoscopy. A patient undergoes general anesthesia and a head and neck surgeon can more carefully examine the throat and the tumor’s extent. A small surgical instrument can gently remove tissue from the tumor to confirm the diagnosis.
Often though, a diagnosis can be made by performing a “fine needle aspiration” (FNA) biopsy. In this procedure, a physician administers local anesthesia and then using a small caliber needle withdraws tissue from an enlarged lymph node in the neck.
Regardless of the route, tissue from the tumor or lymph node metastasis is then given to a pathologist. A pathologist is a physician who can perform a variety of tests and examine this tissue under a microscope to confirm or to rule out cancer.
The multidisciplinary team of doctors of the Stanford Head & Neck Cancer Program are highly experienced in using state-of-the-art cancer treatments. The program’s multispecialty team consists of head and neck surgeons, medical oncologists, radiation oncologists, speech language pathologists, registered dieticians, and a host of other individuals supporting each patient through his or her care journey.
Treatment for oropharyngeal cancer relies on using either surgery or radiation, with or without chemotherapy. Treatment must be administered to the area of the throat where the tumor arises but also lymph nodes in the neck that might be involved.
The Stanford Head & Neck Cancer Center aims to reduce the toxicity and side effects associated with treatment for HPV-associated OPC through precision medicine: using robotic surgery, intensity-modulated radiation therapy and molecular targeted chemotherapy.
Robotic head and neck surgery provides patients with an option for a minimally invasive approach to remove oropharyngeal cancer and quickly return patients to daily life. Instead of facing seven weeks of radiation therapy and chemotherapy, patients undergo a single surgical procedure that may eliminate the need for further treatment or reduce the dose—and associated side effects—of post-operative radiation.
“RapidArc" intensity-modulated radiotherapy (IMRT) can increase the delivery of radiation to the tumor while minimizing collateral damage to critical structures in the head and neck.