Submandibular Gland Cancer

~Introduction

Submandibular gland cancer is a rare but significant malignancy arising from one of the major salivary glands located beneath the lower jaw. Although salivary gland tumors constitute less than 5% of all head and neck cancers, malignancies involving the submandibular gland deserve special attention due to their unique biological behaviour, diagnostic challenges, and the critical anatomical structures surrounding the gland. These tumors can be aggressive, often presenting with advanced locoregional spread, and require a combination of clinical expertise, imaging precision, and surgical skill for optimal management.

This article provides an in-depth exploration of submandibular gland cancer, including anatomy, epidemiology, causes, symptoms, diagnostic techniques, staging, treatment options, prognosis, prevention strategies, and quality-of-life considerations.

~Anatomy of the Submandibular Gland

The submandibular glands are paired salivary glands located beneath the mandible (lower jaw), wrapped around the posterior edge of the mylohyoid muscle. They are responsible for producing approximately 70% of resting (unstimulated) saliva in the mouth, essential for lubrication, digestion, and maintenance of oral health.

Each submandibular gland has:

Superficial and deep lobes
Wharton's duct, which empties saliva under the tongue
Proximity to critical structures:
- Lingual nerve
- Hypoglossal nerve
- Facial artery and vein

The anatomical complexity makes surgical treatment of tumors in this gland challenging. Tumors can easily spread to regional lymph nodes due to rich lymphatic drainage.

~Epidemiology

Submandibular gland cancers are uncommon. Among all salivary gland malignancies:

Parotid gland tumors are the most common.
Submandibular gland cancers account for 5–15% of cases.
Approximately 40–50% of submandibular gland tumors are malignant—much higher compared to parotid tumors (20–25%).

They typically occur in individuals between 50 and 70 years, but can develop at any age. There is no strong gender predilection, though some studies suggest a slight male dominance.

~Types of Submandibular Gland Cancer

Several histological subtypes can arise from the submandibular gland. The most common include:

1. Adenoid Cystic Carcinoma (ACC)

Known for slow growth but aggressive perineural invasion.
High tendency for recurrence and distant metastasis, especially to lungs.

2. Mucoepidermoid Carcinoma

Ranges from low-grade (slower, less aggressive) to high-grade (rapid, invasive).
One of the most common salivary gland malignancies.

3. Adenocarcinoma, NOS (Not Otherwise Specified)

A group of cancers that do not fit into specific categories.
Usually high-grade and aggressive.

4. Acinic Cell Carcinoma

Less common in submandibular glands.
Generally low-grade but may recur.

5. Salivary Duct Carcinoma

Highly aggressive and often diagnosed in advanced stages.

6. Carcinoma ex Pleomorphic Adenoma

Malignant transformation of a previously benign pleomorphic adenoma.
Indicates long-standing, untreated tumors.

Understanding the tumor type helps determine aggressiveness, treatment planning, and prognosis.

~Causes and Risk Factors

The exact causes of submandibular gland cancer are not fully understood, but certain risk factors are recognized:

1. Radiation Exposure

Prior radiation therapy to the head or neck significantly increases risk.
Environmental or occupational radiation exposure may also play a role.

2. Tobacco and Alcohol

While strongly linked to oral cavity and laryngeal cancers, the association is weaker for salivary gland cancers.
However, combined heavy tobacco and alcohol use may raise overall risk.

3. Genetic Mutations

Certain chromosomal abnormalities and gene mutations (e.g., MYB-NFIB fusion in ACC) contribute to tumor formation.

4. Viral Infections

Rare associations with Epstein–Barr virus (EBV) and Human Papillomavirus (HPV) have been documented in some subtypes.

5. Occupational Exposure

Prolonged exposure to:

Nickel compounds
Asbestos
Rubber manufacturing chemicals

may increase risk.

6. Age

Incidence increases with age, especially beyond 50 years.

~Symptoms and Clinical Presentation

Submandibular gland cancer may present gradually or rapidly depending on the tumor type. Common symptoms include:

1. Lump Under the Jaw

Firm, often painless swelling near the submandibular region.
Rapid growth suggests high-grade malignancy.

2. Pain or Discomfort

Particularly significant in adenoid cystic carcinoma due to nerve involvement.

3. Difficulty Swallowing (Dysphagia)

4. Numbness or Tingling

Caused by tumor involvement of the lingual nerve.

5. Facial Weakness

Indicates tumor infiltration into nearby nerves.

6. Ulceration or Fixation of the Mass

Sign of advanced disease.

7. Lymph Node Enlargement

Spread to cervical lymph nodes is common.

8. Reduced Saliva Output or Dry Mouth

Less common but possible in large tumors obstructing Wharton's duct.

Any persistent mass in the submandibular region should be evaluated promptly.

~Diagnosis

Accurate diagnosis requires a structured approach involving clinical evaluation, imaging, and tissue sampling.

1. Physical Examination

The doctor palpates the gland, checks for:

Size, consistency
Fixation to skin or deeper tissue
Cervical lymph node involvement

2. Imaging Studies

Ultrasound

Often the first imaging modality.
Helps differentiate solid vs cystic lesions.
Useful for guiding fine-needle aspiration (FNA).

CT Scan

Evaluates tumor extent, lymph nodes, and bone involvement.

MRI

Superior for assessing perineural invasion (particularly in ACC).
Helps distinguish malignant from benign tumors.

PET-CT

Useful for detecting metastasis in aggressive cancers.

3. Fine-Needle Aspiration Cytology (FNAC)

Minimally invasive and widely used.
Provides initial cytological diagnosis.
High sensitivity for distinguishing malignant from benign tumors.

4. Core Needle Biopsy

Provides more tissue than FNAC.
Helpful when FNA results are inconclusive.

5. Histopathological Examination

Performed after surgical removal; essential for determining:

Tumor type
Grade
Margins
Perineural and lymphovascular invasion

~Staging

Staging follows the AJCC TNM (Tumor–Node–Metastasis) system:

T — Tumor Size & Extent

T1–T2: Confined within gland
T3–T4: Larger tumor, invasion of surrounding tissues

N — Nodal Involvement

Ranges from N0 (none) to N3 (extensive nodal spread)

M — Metastasis

M0: No distant spread
M1: Spread to lungs, bones, liver, etc.

Accurate staging is critical for planning treatment and predicting survival.

~Treatment Options

Management typically involves a combination of surgery, radiation therapy, and in select cases, chemotherapy.

1. Surgery (Primary Treatment)

The cornerstone of treatment for most submandibular gland cancers.

Standard Procedure: Submandibular Gland Excision

Complete removal of the gland along with the tumor.

Neck Dissection

Performed when:

Cervical lymph nodes are clinically involved
High-grade tumors with risk of metastasis

Nerve Preservation

Great care is taken to preserve:

Marginal mandibular nerve
Hypoglossal nerve
Lingual nerve

However, advanced tumors may require nerve resection.

Reconstruction

May be needed in large excisions to restore aesthetics and function.

2. Radiation Therapy

Often recommended post-surgery, especially when:

Margins are close or positive
Perineural invasion is present
High-grade histology
Lymph nodes are involved

Radiation is also used in inoperable tumors.

Advanced techniques:

IMRT (Intensity-Modulated Radiation Therapy)
Proton therapy (rare but useful in reducing collateral damage)

3. Chemotherapy

Chemotherapy has limited effectiveness but may be used:

In metastatic disease
Along with radiation (chemoradiation) in advanced cases
For palliative care

Agents commonly used include cisplatin, carboplatin, and 5-FU.

4. Targeted Therapy & Immunotherapy

Still in experimental stages but promising for certain tumors:

HER2-positive salivary duct carcinoma may respond to trastuzumab.
ACC research focuses on MYB oncogene targets.

~Prognosis and Survival Rates

Prognosis depends on:

Tumor type
Grade
Perineural invasion
Nodal involvement
Surgical margins

General survival rate estimates:

Low-grade tumors: 70–90% 5-year survival
High-grade tumors: 30–50% 5-year survival
Adenoid cystic carcinoma:
- High recurrence rates
- Long-term survival decreases significantly after 10 years

Early diagnosis greatly improves outcomes.

~Complications

1. Surgical Complications

Nerve damage (facial asymmetry, tongue weakness)
Hematoma
Infection
Scarring

2. Radiation Complications

Dry mouth (xerostomia)
Skin reactions
Difficulty swallowing
Altered taste

3. Cancer-Related Complications

Recurrence
Metastasis
Persistent nerve pain

~Prevention

There is no guaranteed prevention method, but risk can be reduced by:

Avoiding unnecessary radiation exposure
Avoiding tobacco and excessive alcohol use
Maintaining good oral hygiene
Seeking prompt evaluation of neck masses
Avoiding exposure to industrial carcinogens
Regular medical check-ups if there is a family history of head and neck cancers

~Living with Submandibular Gland Cancer

Quality of life may be affected by:

1. Dry Mouth

Patients may require:

Frequent hydration
Saliva substitutes
Sugar-free lozenges

2. Speech and Swallowing Difficulties

Speech therapy or swallowing therapy can help.

3. Emotional Stress

Psychological counseling and support groups are beneficial.

4. Long-Term Monitoring

Regular follow-up is essential because:

Recurrence can occur even after many years
ACC especially requires long-term surveillance

Follow-up includes:

Physical examination
MRI or CT scans
Chest imaging for lung metastasis

~Conclusion

Submandibular gland cancer, though rare, is a complex and potentially aggressive malignancy requiring prompt diagnosis and multidisciplinary treatment. With advancements in imaging, surgical techniques, and adjuvant therapies, patient outcomes have significantly improved. However, the prognosis depends heavily on early detection, accurate histopathological diagnosis, and appropriate surgical management.

Awareness of symptoms—particularly any persistent swelling under the jaw—is crucial for early recognition. Continued research into targeted therapy and immunotherapy offers hope for better management of advanced and recurrent cases in the future.

Thursday, November 27, 2025