Although salivary gland cancer is rare, the mortality rate is extremely high. Because the initial symptoms are not obvious, by the time patients develop symptoms such as unknown lumps on the face and difficulty swallowing, it is often already in the advanced stage.

We take you through the symptoms, causes, examination and treatment of salivary gland cancer.

What are salivary glands?

Salivary glands are responsible for producing saliva and releasing enzymes into the mouth that can help digest food. Saliva contains special enzymes and immunoglobulins, which have antibacterial functions. In addition, saliva can also maintain a stable pH value in the mouth, thereby protecting tooth enamel. , prevent tooth decay.

The salivary glands of the human body include four parts: parotid gland, submandibular gland, sublingual gland and minor salivary gland:

1. Parotid gland: The largest salivary gland, located in front and below each ear; about 80% of salivary gland tumors originate from this gland, about 20% of which are malignant.
   
2. Submandibular gland: Located under the jaw, about 10 to 15% of salivary gland tumors originate from here. About 50% of mandibular gland tumors are malignant.
   
3. Sublingual glands and minor salivary glands: Located at the bottom of the mouth under the tongue, they are small in size and have a low chance of developing tumors. However, if tumors occur, more than 50% of them are malignant.

Salivary gland tumors account for about 3% of all head and neck tumors. It is worth noting that the smaller the size of the salivary gland, the higher the probability of malignancy after the tumor develops.

What is salivary gland cancer?

Salivary gland cancer is the formation of cancer cells in salivary gland tissue. It is a very rare disease, accounting for less than 1% of cancer cases and about 3 to 5% of head and neck cancers. It is a rare head and neck malignant tumor with a low incidence rate.

Research shows that salivary gland cancer is most common between the ages of 60 and 70, and the incidence rate in men is three times higher than in women. Clinically, cervical lymph node and distant metastasis often occur, with extremely high recurrence and low survival rate.

Causes of Salivary Gland Cancer

The cause of most salivary gland cancers is unknown. Possible risk factors include:

1. The Elderly: Although salivary gland tumors can occur at any age, they are most common in the elderly.
   
2. Workplace exposure to certain substances: Work involved in rubber manufacturing, asbestos mining, and pipework can increase cancer risk.
   
3. Lymph gland disease: Studies have found that people who have had lymph gland disease are at a greater risk of developing salivary gland tumors.
   
4. The head and neck have been exposed to X-rays: X-rays to the head and neck, and children receiving radiation therapy are important risk factors.

Since the cause of salivary gland cancer is currently unknown, having risk factors does not necessarily mean that you will develop cancer; having no risk factors does not mean that you will not be at risk of cancer. If you think you may be at risk, please consult your physician immediately for advice.

Metastasis and staging of salivary gland cancer

Studies have pointed out that about 60 to 80% of patients with salivary duct cancer will have lymph node metastasis, and 30 to 60% will have distant metastasis. The most common is lung metastasis, followed by liver metastasis and bone metastasis.

Salivary gland cancer can be divided into four stages:

1. Early stage of salivary gland cancer: The tumor is no larger than 2 centimeters, and the cancer cells have not yet reached the lymph nodes.
   
2. Stage II salivary gland cancer: The tumor is larger than 2 cm but not larger than 4 cm, and has not metastasized to lymph nodes.
   
3. Stage III salivary gland cancer: The tumor is larger than 4 centimeters, or the cancer cells have spread to the lymph nodes in the neck.
   
4. Stage IV Salivary Gland Cancer: This is the final stage and the tumor may be of any size and has spread to the following areas:
   
5. nearby soft tissue
   
6. Skin, jawbone, ear canal, facial nerve, skull base, or carotid artery
   
7. Distant parts of the body other than the head and neck
   
8. Large lymph nodes (more than 3 cm) on the same side of the neck as the tumor
   
9. Multiple lymph nodes of any size on the same side of the neck as the tumor
   
10. A lymph node of any size on the opposite side of the neck from the tumor

Salivary gland cancer symptoms

Symptoms of salivary gland cancer include a lump or difficulty swallowing, but it may not cause any symptoms and be discovered during a regular dental or physical exam.

Common symptoms of salivary gland cancer include:

1. A lump (usually painless) in the ear, cheek, chin, lip, or mouth
   
2. The pain in my face won’t go away
   
3. Fluid leaking from the ears
   
4. Facial numbness or weakness
   
5. Difficulty opening mouth
   
6. Hard to swallow

If you have any of the above conditions, please consult your doctor for further advice.

How to check for salivary gland cancer

If an abnormal mass is found, it is recommended to go to the otolaryngology clinic for professional diagnosis first. The examination methods for salivary gland cancer include:
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1. Physical examination and health history: Check for lumps and unusual features, and ask about health habits and past illnesses and treatments.
   
2. MRI (Nuclear Magnetic Resonance)
   
3. CT scan (computed tomography)
   
4. PET scan (positron radiation tomography)
   
5. Endoscopy
   
6. Biopsy
   • Fine needle aspiration (FNA): Using a fine needle to obtain tissue, it is the most common testing method.
   • Slice: Removal of part of a lump or tissue sample that looks abnormal.
   • Surgery: If cancer cannot be diagnosed on FNA or biopsy, you may consider removing the mass and checking for cancer cells.

Because salivary gland cancer is difficult to diagnose, it is recommended that a professional doctor with experience in diagnosing salivary gland cancer perform the examination.

3 major treatments for salivary gland cancer

1. Surgery
   Surgical resection is a common treatment method for salivary gland cancer. Doctors will remove the tumor and surrounding tissue, and sometimes combine it with lymph node dissection in order to completely remove the cancer cells.
   
   After surgery, some patients may need to receive radiation therapy to kill residual cancer cells that cannot be removed by surgery. After surgery, adjuvant therapy may be performed to reduce the risk of cancer recurrence.

2. Radiotherapy
   High-energy X-rays or other radiation are used to kill cancer cells or prevent their growth. Salivary gland cancers are mostly squamous flat epithelial cell carcinomas that are sensitive to radiation, so they are often used as primary therapy or as adjuvant therapy for surgical resection. The course of radiotherapy is usually 7 weeks, and side effects will begin after the first week: decreased saliva, Dry mouth, difficulty softening food, and difficulty chewing.
   
   Long-term side effects of radiotherapy include dry mouth and difficulty in taking care of teeth, etc. You should maintain oral hygiene and regular dental follow-up examinations in a timely manner to reduce the occurrence of tooth decay. The neuromuscular tissue that has been irradiated is prone to fibrosis or early degeneration. Depending on the irradiation site, there may be difficulty opening the mouth, stiffness of the shoulder and neck tissue, difficulty in swallowing, and deterioration of vision and hearing. Although some side effects can be alleviated by medications, the most important thing is to carry out early and moderate rehabilitation, exercise and perseverance, which can reduce and prevent the occurrence of serious chronic side effects.

3. Chemotherapy
   Drugs are used to kill cancer cells or prevent their growth. Chemotherapy drugs can be taken orally or injected into veins or muscles. In the late stage of salivary glands, chemotherapy and radiation can be combined for treatment. However, chemotherapy is not currently included in the standard treatment for salivary gland cancer, so it is still It is necessary to make a professional diagnosis by a doctor before deciding whether to proceed.

Salivary gland cancer mortality and survival rates

Most patients with salivary gland cancer die within 5 years, with a mortality rate of 60% to 75%, and it is extremely malignant. Research shows that the average 5-year survival rate of salivary gland cancer in the first stage is 86%, the average 5-year survival rate in the second stage is 66%, the third stage is 53%, and the fourth stage is 32%.