The submandibular glands are a pair of major salivary glands located beneath the lower jaw, on the floor of the mouth. They produce a significant portion of saliva, especially at rest. Saliva moistens the mouth, aids chewing and swallowing, initiates digestion, and maintains oral hygiene. Rarely, these glands can develop cancerous tumors.
Symptoms and Risk Factors
A persistent lump below the jawbone is the most common symptom of submandibular gland cancer, often painless, though some experience pain that may be mistaken for inflammation. Other symptoms include numbness or weakness on one side of the face, problems with swallowing, or difficulty opening the mouth completely. While suggestive, these symptoms can also be caused by non-cancerous conditions, making medical evaluation important.
The precise cause of submandibular gland cancer is frequently unknown, yet several factors may increase risk. Advanced age is a factor, with most diagnoses in individuals over 50, and slightly more men affected. Prior radiation therapy to the head and neck (e.g., for other cancers) is a known risk factor, with risk correlating to exposure. Certain workplace exposures, including nickel alloy dust, silica dust, asbestos mining, plumbing equipment, rubber manufacturing, and some types of woodworking, have also been suggested as risk factors.
Diagnosis and Staging
Diagnosing submandibular gland cancer begins with a thorough physical examination. A doctor will inspect and palpate the area under the jaw, cheeks, neck, and inside the mouth to check for lumps, swelling, or changes in facial symmetry or muscle movement. The examination also involves checking for numbness or weakness in facial areas, as these can indicate nerve involvement.
Imaging tests are often used to further evaluate any suspicious mass. Computed tomography (CT) scans use X-rays to create detailed cross-sectional images, helping to determine the tumor’s size, shape, location, and whether it has extended into surrounding tissues or lymph nodes. Magnetic resonance imaging (MRI) utilizes magnetic fields and radio waves to produce detailed images, especially useful for assessing cancer spread along nerves or to soft tissues. Positron emission tomography (PET) scans involve injecting a small amount of radioactive sugar, which cancer cells tend to absorb more actively, helping to identify distant spread or to plan treatment.
A biopsy is the most definitive diagnostic step, involving a tissue sample for microscopic examination. Fine-needle aspiration (FNA) biopsy is common, using a thin needle to withdraw cells from the lump, often guided by ultrasound. Sometimes, a surgical biopsy, removing a small tissue piece, may be performed. The pathologist’s analysis confirms the presence of cancer cells and helps determine the specific type of cancer.
Once cancer is confirmed, staging determines the disease’s extent. Staging systems, such as the TNM (Tumor, Node, Metastasis) system, classify the cancer based on the tumor’s size (T), whether it has spread to nearby lymph nodes (N), and if it has spread to distant parts of the body (M). This information assigns a stage (typically I to IV), guiding treatment planning.
Treatment Approaches
Surgery
Surgery is the primary treatment for submandibular gland cancer. The procedure, a submandibular gland excision, involves an incision in the upper neck, typically below the jawline, to remove the entire affected gland. Surgeons also remove a margin of surrounding healthy tissue to ensure all cancer cells are extracted. This requires meticulous care due to the proximity of important nerves, including the marginal mandibular nerve (influencing lower lip movement) and the lingual and hypoglossal nerves (controlling tongue sensation and movement).
If cancer has spread or is suspected to have spread to nearby neck lymph nodes, a neck dissection may also be performed. This procedure involves removing lymph nodes from specific neck areas (e.g., Level I) to prevent further disease spread. The extent of the neck dissection depends on the tumor’s size, grade, and whether lymph nodes appear enlarged or suspicious on imaging. The goal is to remove any cancerous lymph nodes while preserving as much healthy tissue and nerve function as possible.
Radiation Therapy
Radiation therapy is often used as a secondary treatment after surgery for submandibular gland cancer. This adjuvant therapy is considered if the cancer is aggressive, has a higher risk of recurrence, or if some cancer cells may have remained after surgery. Its aim is to destroy any microscopic cancer cells in the treated area, reducing recurrence.
External beam radiation is the most common form, directing high-energy rays or particles to the precise tumor area. Treatments are administered daily, five days a week, for four to seven weeks, usually beginning about six weeks after surgery. Radiation can also be used as a primary treatment if surgery is not feasible or to manage symptoms in advanced cases.
Chemotherapy
Chemotherapy is used less often for submandibular gland cancer than surgery and radiation therapy. It is primarily reserved for metastatic disease, where cancer has spread to distant body parts. Chemotherapy drugs travel through the bloodstream to target and destroy cancer cells throughout the body.
Due to the rarity of this cancer, there is no single standard chemotherapy regimen, but combinations like cisplatin, doxorubicin, and fluorouracil are sometimes used. Sometimes, chemotherapy may be given alongside radiation therapy (chemoradiation) to enhance radiation effectiveness, especially for unresectable tumors or those with a high recurrence risk. This approach aims to make cancer cells more sensitive to the effects of radiation.
Recovery and Post-Treatment Considerations
Following submandibular gland cancer treatment, patients may experience various challenges and side effects. One concern is temporary or, less commonly, permanent damage to nearby facial nerves, particularly the marginal mandibular nerve. Injury to this nerve can result in weakness or drooping of the lower lip, affecting the ability to smile symmetrically. While most nerve issues are temporary, resolving over weeks to months as nerves heal, some individuals may experience lasting effects.
Another common side effect, especially after radiation therapy, is persistent dry mouth (xerostomia). Radiation can damage salivary glands, reducing saliva production, which causes discomfort, difficulty speaking and swallowing, and an increased risk of dental problems like cavities. Management strategies for dry mouth include avoiding irritating foods and drinks, using saliva substitutes, and exploring therapies to stimulate saliva production.
Regular follow-up appointments are important to monitor for recurrence. These visits involve physical examinations of the head and neck, along with surveillance imaging tests (e.g., CT, MRI, or PET scans). Appointments are more intensive in the first two years after treatment, when recurrence risk is highest, gradually becoming less frequent, often annually after five years. Long-term follow-up is important, as some types of submandibular gland cancer can recur many years after initial treatment.