Human Papillomavirus (HPV) in the neck primarily refers to HPV-related oropharyngeal cancer, a type of head and neck cancer affecting the back of the throat, including the tonsils and base of the tongue. This cancer has seen a notable increase in incidence, particularly in Western countries, highlighting its growing prevalence and public health concern.
How HPV Causes Head and Neck Cancer
Human Papillomavirus is a group of DNA viruses that can infect skin and mucous membranes. Over 200 types of HPV exist, but about 40 types spread through direct sexual contact, including to the mouth and throat. High-risk HPV types, particularly HPV-16, are strongly associated with oropharyngeal cancers. HPV-16 alone causes approximately 90% of HPV-positive oropharyngeal cancers, with HPV-18 and HPV-33 accounting for most other cases.
Oral HPV often transmits through oral sex or other direct mouth-to-mouth contact. While many are exposed to oral HPV and most infections clear naturally within one to two years, some persist. Persistent infection with high-risk HPV types can lead to cellular changes over many years, typically taking decades to develop into cancer.
HPV leads to cancer by integrating viral DNA into the host cell’s genome. Once integrated, the virus expresses oncoproteins, primarily E6 and E7. These oncoproteins interfere with the cell’s natural tumor suppressor mechanisms. E6 targets and degrades the p53 tumor suppressor protein, which controls cell growth and triggers cell death. Similarly, E7 binds to and inactivates the retinoblastoma protein (pRb), another tumor suppressor regulating cell cycle progression.
By inactivating p53 and pRb, E6 and E7 proteins allow infected cells to bypass normal cell cycle checkpoints and undergo uncontrolled division. This disrupts cellular regulation, promoting genomic instability and preventing programmed cell death. Over time, these changes can progress to malignant transformation and cancer. Continuous expression of E6 and E7 is necessary to maintain the cancerous state in HPV-positive oropharyngeal cells.
Recognizing Symptoms and Diagnosis
HPV-related oropharyngeal cancer may present with various symptoms, though some individuals experience none initially. Common symptoms include a persistent sore throat, difficulty swallowing (dysphagia), or pain when swallowing. Patients might also notice ear pain (otalgia), a change in voice or hoarseness, or unexplained weight loss. A lump in the neck, often due to cancer spreading to lymph nodes, is a frequent initial symptom, especially in HPV-associated cases where the primary tumor site might be asymptomatic.
Diagnosis typically begins with a thorough physical examination, where a doctor checks the neck for lumps or swelling and examines the mouth and throat. This often includes a nasopharyngoscopy, using a flexible tube with a camera to visualize the oropharynx and larynx. If suspicious areas are found, a biopsy collects tissue samples for laboratory analysis. This can involve an endoscopic biopsy, where samples are taken during an endoscopy, or a fine needle aspiration if a neck lump is present.
After a biopsy confirms cancer, imaging tests determine the cancer’s stage and spread. These include computed tomography (CT) scans, magnetic resonance imaging (MRI) of the head and neck, and positron emission tomography (PET) or PET-CT scans. An HPV DNA test on tumor cells confirms high-risk HPV, aiding staging and treatment planning. Blood tests also assess overall patient health before treatment.
Treatment Approaches and Outlook
Treatment for HPV-positive oropharyngeal cancer is multidisciplinary and tailored to the individual patient, considering the cancer’s stage and characteristics. Primary treatment modalities include surgery, radiation therapy, chemotherapy, or a combination. For early-stage tumors, such as those 4 centimeters or smaller without lymph node metastasis, minimally invasive surgery or radiation therapy alone may be recommended to preserve organ function and reduce toxicity. Minimally invasive surgical options include transoral robotic surgery or transoral laser microsurgery.
For more advanced stages, concurrent chemoradiation therapy is a common treatment choice. Chemotherapy is administered alongside radiation to enhance its effectiveness. While induction chemotherapy has been explored, studies have not consistently shown an improvement in survival, so it is not routinely used for HPV-positive oropharyngeal squamous cell carcinoma. Immunotherapy, which helps the body’s immune system fight cancer, is also emerging as a treatment option, particularly for recurrent or metastatic disease. HPV-positive tumors tend to respond better to immunotherapy than HPV-negative ones.
The prognosis for HPV-positive oropharyngeal cancer is generally favorable compared to HPV-negative cases. This is largely due to HPV-positive tumors being more responsive to radiation therapy and chemotherapy. For localized HPV-induced oropharyngeal cancers, nearly all can be eradicated. While distant recurrence can still occur, particularly to the lungs, overall survival rates are generally higher. For instance, some studies indicate a 3-year overall survival rate of approximately 60-70% for HPV-positive oropharyngeal squamous cell carcinoma.
Prevention and Risk Reduction
The primary method for preventing HPV-related oropharyngeal cancer is HPV vaccination. The HPV vaccine protects against high-risk HPV types commonly associated with these cancers, particularly HPV-16 and HPV-18. The Centers for Disease Control and Prevention (CDC) recommends HPV vaccination for 11- to 12-year-olds, and for individuals through age 26 if not previously vaccinated. Some adults aged 27 through 45 may also consider the vaccine after consulting their doctor about their risk and potential benefits.
Beyond vaccination, practicing safe sexual behaviors, including reducing the number of sexual partners, can help reduce the risk of oral HPV infection. Other risk factors that can interact with HPV to increase cancer risk include tobacco use and alcohol consumption. These substances can independently contribute to oropharyngeal cancer, and their combined use with HPV infection can further elevate the risk.
Certain demographics may also have a higher incidence of HPV-related oropharyngeal cancer. For example, the highest burden is observed in middle-aged and increasingly older white men. Oral HPV infection prevalence is also higher among males compared to females in the U.S. These differences underscore the importance of targeted prevention efforts and awareness campaigns for specific populations.