Oral cancer presents a significant challenge within the field of oncology, silently impacting millions across the globe. It encompasses malignancies affecting various areas including the lips, tongue, gums, floor of the mouth, palate (roof of the mouth), buccal mucosa (inner part  of the cheeks), and  the oral part of pharynx. Oral cancer development is primarily associated with lifestyle choices and risk factors such as tobacco use, excessive alcohol consumption, and viral infections. Unfortunately, its insidious nature frequently leads to late-stage detection and unfavorable outcomes. Therefore, early detection  and thorough management are crucial in addressing this life-threatening condition.

Symptoms

The manifestation of oral cancer exhibits a broad spectrum, frequently resembling benign conditions, which can delay diagnosis. However, persistent symptoms warrant attention and they include;

• a persistent sore or irritation in the mouth, lip, or throat that fails to heal 

• presence of a lump or thickening within the oral cavity

• difficulty chewing, swallowing, or speaking

• numbness in the mouth or lips

• unexplained instances of bleeding

• swelling of the jaw or neck

• ear pain

• weight loss

Diagnosis

Diagnosing oral cancer requires a comprehensive approach considering factors like suspected cancer type, symptoms, age, and general health history. Tests include:

Medical history and physical examination: Medical history and physical examination are crucial steps in diagnosing oral cancer. Medical history taking involves assessing the patient's medical history, including any relevant symptoms and risk factors such as tobacco or alcohol use. Physical examination involves checking for any abnormalities or suspicious lesions in the mouth, throat, and surrounding areas. This includes palpating the neck, lips, gums, cheeks, and the area behind the nose, as well as examining the larynx (voice box) and lymph nodes of the neck for any signs of swelling or masses.

Endoscopy: It involves the use of a flexible or rigid endoscope to examine the mouth and throat. Following endoscopic examinations may be employed depending on the location of the tumor:

• Laryngoscopy to view the larynx

• Pharyngoscopy to view the pharynx, or

• Nasopharyngoscopy to view the nasopharynx.

Histopathological examination of the biopsy specimen: A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definitive  diagnosis. The type of biopsy performed will depend on the location of the lesion  and they include a fine needle aspiration biopsy (cells are removed using a thin needle inserted directly into the suspicious area) or oral brush biopsy (it uses a small brush to gather cell samples of a suspicious area during routine examination).

HPV testing: HPV testing plays a vital role in diagnosing oral cancer, particularly in cases where the human papillomavirus (HPV) is suspected to be a contributing factor. This test involves analyzing a sample of tissue, typically obtained during a biopsy, to determine if HPV DNA is present. 

Imaging modalities: Imaging modalities are crucial in diagnosing and staging oral cancer, providing detailed insights into tumor size, location, and spread. Common imaging techniques include:

• Chest and dental X-rays: Used for initial assessment of bone involvement and tumor invasion.

• Computed Tomography (CT) Scan: Produces detailed cross-sectional images of the oral cavity and surrounding structures. Provides details on tumor size and lymph node involvement.

• Magnetic Resonance Imaging (MRI): Offers detailed soft tissue imaging, particularly useful for assessing tumor extent in complex anatomical regions like the base of the tongue and tonsils, as well as detecting perineural spread.

• Ultrasonography: Helps evaluate lymph node involvement and assess tumor depth in superficial lesions, providing real-time imaging without radiation exposure.

• Positron Emission Tomography (PET) Scan: Detects metabolic activity in cancer cells, aiding in the identification of primary tumors, and metastases, and assessing treatment response.

• Barium swallow: This procedure, also known as an upper GI (gastrointestinal) series, involves a series of X-rays of the esophagus and stomach. It serves not only to detect other potential cancers but also to assess swallowing function.

Specialized tests for oral cancer:

• Autofluorescence imaging: Utilizes a blue light to illuminate the mouth, with healthy tissue emitting florescence. Areas lacking florescence may indicate potential cancerous or pre-cancerous lesions.

• Mucosal staining: Involves applying toluidine blue staining  to suspected areas. Persistent blue areas after rinsing may suggest cancerous regions.

• Chemiluminescent light: Patients rinse with a mild acid solution, and suspicious areas are examined under a special light. Cancerous cells tend to reflect light, distinguishing them from healthy cells.

Management

The management of oral cancer demands a concerted effort from an interdisciplinary team comprising oncologists, surgeons, dentists, and supportive care specialists. Treatment approaches are customized based on the size of the primary tumor, its depth of infiltration, and the location of the primary tumor, as well as the patient's overall health status and preferences. Treatment for the cancer or symptom relief may involve one or more of the following therapies.

1. Surgery

Surgery serves as the primary treatment for oral cancer, tailored to its type, extent, and stage. Various surgical techniques aim to completely remove cancer from the mouth, including the removal of affected lymph nodes. Some patients may require plastic or reconstructive surgery to restore speech, swallowing, and appearance.

Reconstruction typically occurs concurrently with cancer removal surgery. In certain cases, tissues from other parts of the body, such as skin, muscle, or bone, are utilized for oral reconstruction. Additionally, specially crafted dental prostheses or implants may be necessary to optimize function and appearance.

2. Radiation therapy

Radiation therapy employs focused energy beams to eradicate cancer cells. Various types of radiation therapy are utilized in oral cancer treatment, including:

• Intensity modulated radiation therapy (IMRT): Delivers multiple radiation beams of varying intensities directly to the tumor, maximizing the dose.

• Proton therapy: Minimizes damage to surrounding healthy tissue while delivering a potent radiation dose.

• Stereotactic body radiation therapy (SBRT): Precisely targets tumors with high doses of radiation, primarily used in specific oral cancer cases.

• Stereotactic radiosurgery (SRS): Non-invasive treatment employing numerous small radiation beams to accurately target tumors with a single high dose. Effective for treating small-area tumors in the head and neck region.

3. Chemotherapy

Chemotherapy utilizes drugs to kill cancer cells, control their growth, or alleviate disease symptoms. It may involve single or combination drug therapy, administered before or after surgery, or concurrently with radiation therapy, depending on the cancer type and its progression.

4. Chemoradiation

Chemoradiation involves administering chemotherapy concurrently with radiation therapy. This combined approach has demonstrated effectiveness in reducing the size of oral cavity and oropharyngeal tumors, particularly for individuals whose cancers are advanced but not widespread enough for surgery. However, this regimen can be challenging to tolerate, particularly for individuals in poor health. A preferred dosing schedule involves administering cisplatin every 3 weeks, totaling 2 to 3 doses, alongside radiation therapy.

5. Targeted therapy

Targeted therapy drugs are engineered to impede the growth or spread of cancer by targeting specific molecules necessary for cancer cell survival, multiplication, or spread, as well as the genes responsible for their formation. In oral cancer, targeted therapy is primarily used to treat metastatic disease. Cetuximab (Erbitux) is an FDA-approved targeted therapy, often combined with radiation therapy for this purpose.

6. Immunotherapy

Immunotherapy enhances the immune system's ability to eradicate cancer cells. In the context of oral cancer, immunotherapy is employed for recurrent or metastatic disease. One form of immunotherapy, immune checkpoint inhibitors, prevents cancer cells from deactivating the immune system, allowing it to effectively target the cancer. Pembrolizumab (Keytruda) and nivolumab (Opdivo) are two FDA-approved immunotherapy drugs for treating individuals with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC).

7. Gene therapy

Gene therapy is a promising approach for the treatment of oral cancer, although it is still in the experimental stage. This innovative treatment method involves introducing genetic material into cancer cells to target and disrupt their growth or induce cell death. Gene therapy for oral cancer aims to correct genetic mutations or manipulate cellular pathways involved in cancer development and progression.

8. Photodynamic therapy

Photodynamic therapy (PDT) begins with the administration of a light-sensitive medication known as a photosensitizer. Following this, exposure to light of a specific wavelength, corresponding to the absorbance band of the photosensitizer, is conducted. This process triggers the production of cytotoxic free radicals, induced by tissue oxygen, leading to direct tumor cell death, disruption of the microvascular structure, and inflammation at the targeted sites. PDT can serve as a standalone therapy for early lesions or as adjuvant therapy for advanced lesions.

Timely identification of oral cancer symptoms, rapid diagnosis, and systematic treatment is crucial for enhancing prognosis and decreasing mortality rates linked to this condition. Educating individuals about the signs, as well as advocating preventive actions, can substantially alleviate the impact of oral cancer and enhance patient results.