Oropharyngeal Cancer
Our 26th episode explores oropharyngeal cancer, a significant topic in head and neck oncology. Join us as we discuss its impact, key considerations in diagnosis and treatment, and what students may need to know!
Show Notes:
Hello Everyone,
Welcome to The Oto Approach! This podcast is created by a team of ENT residents, staff physicians, and medical students to help you prepare for your ENT rotations and excel during your clinical experiences.
My name is Abhishek, and I will be your host for this episode. I am currently a third-year medical student at the University of Alberta. Today, we’ll be focusing on oropharyngeal cancer, exploring a structured approach to the evaluation and management of patients with this condition. We'll discuss key topics such as risk factors, clinical presentation, diagnostic investigations, and management strategies.
Anatomy
Let's begin with a brief overview of the relevant anatomy. The oropharynx is anatomically defined by the following borders: superiorly by the soft palate, inferiorly by the hyoid bone, and anteriorly where it is continuous with the oral cavity. The oropharynx itself includes critical structures such as the base of the tongue, the vallecula, the tonsillar regions, the soft palate, and the posterior and lateral pharyngeal walls.
In terms of lymphatic drainage, the lymph nodes of the oropharynx are organized into levels based on their anatomical location relative to other structures. This includes:
Level I: Submental and submandibular lymph nodes.
Level II: Upper jugular lymph nodes above the digastric muscle.
Level III: Mid-jugular nodes between the omohyoid and digastric muscles.
Level IV: Lower jugular nodes.
Level V: Posterior triangle nodes.
Retropharyngeal nodes are also relevant for lymphatic spread in oropharyngeal cancer.
This understanding is essential because the lymphatic spread often determines the staging and prognosis of oropharyngeal cancer. The base of the tongue and the anterior tonsillar pillar are the two most common primary sites, representing 47% and 46% of oropharyngeal cancers, respectively.
Etiology
Oropharyngeal cancer can be broadly divided into two categories based on its etiology: HPV-associated and non-HPV-associated. As the rate of smoking in Canada and USA is declining, we are seeing a decrease non-HPV related head and neck cancers. HPV-associated oropharyngeal cancer has been increasing in prevalence and tends to have a better prognosis compared to its counterpart. Non HPV associated cancers are often linked to traditional risk factors such as tobacco and alcohol use. Thus, a thorough social history, including smoking, alcohol use, sexual history, and HPV vaccination status, is crucial for risk stratification. A higher frequency of oral sex and a greater number of sex partners are known to increase the risk of HPV-related head and neck cancer.
HPI
When taking a history, it’s important to ask about symptoms such as a persistent sore throat, also known as odynophagia, a sensation of a lump or foreign body in the throat, difficulty swallowing, also known as dysphagia, or changes in voice. Additionally, constitutional symptoms like unintentional weight loss, fevers, night sweats, and fatigue may suggest a more advanced disease or another pathology such as lymphoma. Patients may also present with ear pain (referred otalgia), hemoptysis, or visible lesions in the mouth or throat.
Past Medical Hx
A detailed past medical history is essential, particularly regarding prior head and neck cancers or other malignancies. It is also important to document any comorbidities, such as cardiovascular disease or diabetes, which might influence the choice of treatment or surgical candidacy.
Past Surgical Hx
Previous surgeries in the head and neck region, especially ENT surgeries or dental procedures, should be documented as they may impact surgical planning, tissue availability, or complicate radiation therapy.
Family Hx
While there is no strong hereditary link for oropharyngeal cancer, it is still worthwhile to ask about a family history of head and neck cancers or other malignancies to provide a complete risk profile.
Social Hx
Social history is a key component in assessing risk factors. Documenting the patient’s smoking status (including pack year history and whether they are currently smoking), alcohol consumption, and any history of betel nut or other tobacco use is crucial. For patients with high-risk behaviors, counseling on lifestyle modifications is also an essential part of the management plan.
Physical Exam
A thorough head and neck exam is essential. Look for visible lesions, ulcers, red or white patches, or asymmetric tonsils. Pay close attention to the base of the tongue, lateral tongue borders, and tonsillar regions. If a lesion persists, it warrants a biopsy. Assess for neck masses, which could indicate lymph node involvement. The oropharynx offers easy access for infection, and its invaginations at the mucosal surface can capture and process viral antigens. Interestingly, the common presenting sign for HPV related head and neck cancer is actually an asymptomatic neck mass typically related to cervical lymph node involvement, rather than other signs or symptoms related to the primary tumor in the oropharynx.
Investigations
Initial investigations should include:
CBC, LFTs, BUN/Creatinine, and calcium levels.
Fine needle aspiration biopsy (FNAB) of suspicious lymph nodes or masses for pathological examination.
HPV testing for the biopsy samples, particularly for HPV-16.
Imaging, such as MRI, CT, or PET scans, may be required for staging and assessing the extent of disease. Consider endoscopic evaluation (laryngoscopy and transoral ultrasound) for a comprehensive view of the lesion.
Staging
The staging of oropharyngeal cancer is based on the TNM (Tumor, Node, Metastasis) staging system, which considers the size and extent of the primary tumor (T), involvement of regional lymph nodes (N), and presence of distant metastasis (M). For oropharyngeal cancer, an additional consideration is the HPV status, as HPV-positive cancers are staged and managed differently due to their distinct biology and typically better prognosis. Generally, the clinical staging for oropharyngeal cancer is as follows:
Tumor (T) Stage:
T1: Tumor ≤ 2 cm in greatest dimension.
T2: Tumor > 2 cm but ≤ 4 cm.
T3: Tumor > 4 cm or extension to the lingual surface of the epiglottis.
T4a: Moderately advanced local disease with invasion into nearby structures like the larynx, extrinsic muscle of tongue, medial pterygoid, hard palate, or mandible
T4b: Very advanced local disease. invades lateral pterygoid muscle, pterygoid plates, lateral nasopharynx, or skull base or encases carotid artery
Node (N) Stage:
N1: Single ipsilateral lymph node ≤ 3 cm.
N2: Multiple ipsilateral nodes, bilateral or contralateral nodes, none larger than 6 cm in greatest dimension.
N3: Any lymph node > 6 cm or or metastasis in any node with clinically overt extranodal extension
Metastasis (M) Stage:
M0: No distant metastasis.
M1: Distant metastasis is present.
HPV-positive vs. HPV-negative:
HPV-positive cancers are usually downstaged compared to HPV-negative cancers due to their more favorable prognosis.
For example, an HPV-positive T1N1 tumor might be classified as Stage I, whereas an HPV-negative tumor with the same characteristics would be considered Stage III.
The staging for HPV (p16+) cancers is slightly different and can be found on the NCCN article: https://www.nccn.org/professionals/physician_gls/pdf/head-and-neck.pdf.
Management
The management of oropharyngeal cancer is dependent on staging.
Early-Stage Disease (Stages I and II)
Radiation therapy or Surgical resection have been shown to be successful in controlling stage I and II disease. The choice of treatment ultimately depends on anticipated functional speech and swallowing and cosmetic outcome of the treatment options, and the available expertise of the surgeon or radiation oncologist.
Transoral Robotic Surgery (TORS) and Transoral Laser Microsurgery (TLM) offer precision with minimal disruption to surrounding structures.
Radiation therapy is an alternative for patients with contraindications to surgery or for whom surgery might cause significant morbidity.
Considerations for choosing surgery vs. radiation:
Surgery: Preferred for accessible tumors with favorable anatomy, offers quick resolution, and allows for pathological staging.
Radiation: Non-invasive and generally associated with better functional outcomes for early lesions in sensitive areas like the base of tongue.
HPV-Positive Early-Stage Disease: Surgical management is often preferred to minimize the radiation dose, especially in younger patients, due to the favorable prognosis.
Intermediate to Locally Advanced Disease (Stages III and IVA/B)
Multimodal Therapy: Combined chemoradiation is typically the treatment of choice if the tumor is not resecable surgically, as it allows for organ preservation and improved survival rates.
Primary Surgery with Adjuvant Therapy: May be considered for resectable tumors, especially if achieving negative margins is possible.
Postoperative radiotherapy or chemoradiation is indicated for high-risk pathological features, such as:
Positive margins.
Extracapsular spread in lymph nodes.
Perineural invasion.
Lymphovascular invasion.
HPV-Positive Intermediate Disease: May be treated with de-escalated regimens (e.g., lower doses of radiation) in the context of clinical trials, given the good prognosis with standard treatment.
Advanced Disease (Stage IV and Beyond)
Definitive Chemoradiation:
Concurrent chemoradiation remains the mainstay for advanced-stage tumors.
Induction chemotherapy (e.g., TPF regimen: Taxane, Platinum, and 5-Fluorouracil) may be used in select cases to reduce tumor burden before definitive chemoradiation.
Surgical Management:
Reserved for tumors that are either resectable or for salvage surgery in cases of persistent or recurrent disease.
Radical surgical options may include mandibulectomy, maxillectomy, or composite resections depending on the extent of local spread.
Palliative Options:
For patients with unresectable or metastatic disease, palliative chemotherapy, immunotherapy (e.g., Pembrolizumab for PD-L1 positive tumors), and palliative radiation can be considered.
Symptom management is critical, focusing on pain control, airway management, and nutritional support.
Prognosis
After completing therapy, patients undergo surveillance for recurrent or metastatic disease.
Prognosis for oropharyngeal cancer is influenced by a variety of factors, including the cancer’s stage at diagnosis, HPV status, lymph node involvement, and the patient’s overall health. Generally, HPV-positive oropharyngeal cancers tend to have a more favorable prognosis compared to HPV-negative cancers. The 5-year relative survival rate for localized disease (where cancer has not spread beyond the oropharynx) is approximately 83.7%, while for regional disease (spread to nearby lymph nodes or tissues), the survival rate is around 64.2%. However, for distant metastatic disease, the 5-year relative survival drops significantly to 38.5%, highlighting the importance of early detection and treatment.
Key prognostic factors include the number of lymph nodes involved, tumor size, margin status (whether cancer cells are found at the edge of the surgically removed tissue), and spread to surrounding tissues like muscles, nerves, or bones. A positive surgical margin is associated with a higher risk of recurrence. Additionally, factors like patient age, performance status, and comorbidities (such as cardiovascular or pulmonary conditions) play a crucial role in determining overall outcomes. Importantly, patients who continue to smoke or consume alcohol during treatment tend to have poorer outcomes due to reduced treatment efficacy and increased complications.
-----------------------
A special thanks to Dr. Sarah Almas for helping write this podcast. Thank you for tuning into this podcast.
