Cancer Type

nasopharyngeal cancer Introduction

According to data from the Hong Kong Cancer Registry, approximately 70% of new nasopharyngeal carcinoma cases in 2018 were diagnosed at stage III or IV. Understanding the pathological classification, causes, symptoms, stages, spread rate, and latest treatment methods of nasopharyngeal carcinoma is crucial for early detection and treatment.

Introduction to nasopharyngeal cancer

Nasopharyngeal carcinoma is a malignant tumor formed by the abnormal growth of cells located in the nasopharynx. It is a common head and neck cancer in Hong Kong.
According to the latest data from the Hong Kong Cancer Registry, there were 831 new cases of nasopharyngeal carcinoma in Hong Kong in 2018, of which 634 were male and 197 were female, with a male-to-female ratio of approximately 3:1. The total number of deaths was 295, and the median age of onset was between 50 and 60 years old. Treatment for nasopharyngeal carcinoma primarily involves radiotherapy (electrotherapy), with the latest treatments including advanced techniques such as intensity-modulated radiotherapy (IMRT).

I. Pathological classification of nasopharyngeal cancer

The World Health Organization classifies nasopharyngeal carcinoma according to cell type:

Squamous cell carcinoma (squamous cell carcinoma)
Keratinizing undifferentiated carcinoma (keratinizing undifferentiated carcinoma)
Non-keratinizing undifferentiated carcinoma (non-keratinizing undifferentiated carcinoma)

Studies show that keratinizing undifferentiated carcinoma and nonkeratinizing undifferentiated carcinoma are most closely related to the Epstein-Barr virus (EBV), and these two types of nasopharyngeal carcinoma are also the most common types among Chinese people. Squamous cell carcinoma is more associated with smoking.

ii Causes and symptoms of nasopharyngeal cancer

Causes of nasopharyngeal cancer

The exact causes of nasopharyngeal carcinoma are still under active investigation by the medical community, but based on epidemiological studies, the following risk factors have been identified:

Family inheritance
Has been infected with EB (Epstein-Barr) virus
Eat too much salted fish, smoked or pickled food
smoking

Symptoms of nasopharyngeal cancer

Common symptoms of nasopharyngeal cancer include：
- Unilateral tinnitus, earplugs or hearing loss
- Unknown mass in the neck
- Blood in the nose, runny nose, or sputum and salivation
If the disease progresses to the middle or late stages, the tumor may invade adjacent tissues of the nasopharynx, causing symptoms such as headache, facial numbness, difficulty swallowing, hoarseness, and diplopia (repeated images in vision).

III. Staging of nasopharyngeal cancer

The American Joint Committee on Cancer (AJCC) 8th edition staging system (2018) classifies nasopharyngeal carcinoma into stages 0 to IV based on TNM status, with stage IV further subdivided into IVA and IVB.

T (tumor): refers to the size of the tumor and its spread to surrounding tissues.

Tumor size

Tx	The primary tumor cannot be evaluated
Tis	Carcinoma in situ
T0	No primary tumor could be found, but EB virus-positive cervical lymph node metastasis was confirmed.
T1	The tumor is confined to the nasopharynx or extends to the oropharynx or nasal cavity, but without parapharyngeal invasion.
T2	The tumor spread from the nasopharynx to the parapharyngeal or adjacent muscles.
T3	The tumor has invaded the skull base, cervical vertebrae, pterygoid structures, or sinuses.
T4	Tumors invading the intracranial cavity, cranial nerves, hypopharynx, orbit, parotid gland, or lateral pterygoid muscle.

N (lymph nodes): Indicates the extent and degree of tumor spread to regional lymph nodes.

Condition and extent of lymph node involvement

Nx	Cervical lymph nodes cannot be assessed
N0	No cervical lymph node dissemination
N1	No primary tumor could be found, but EB virus-positive cervical lymph node metastasis was confirmed.
N2	The tumor is confined to the nasopharynx or extends to the oropharynx or nasal cavity, but without parapharyngeal invasion.
N3	The tumor spread from the nasopharynx to the parapharyngeal or adjacent muscles.
T3	The tumor has invaded the skull base, cervical vertebrae, pterygoid structures, or sinuses.
T4	Tumors invading the intracranial cavity, cranial nerves, hypopharynx, orbit, parotid gland, or lateral pterygoid muscle.

M (metastasis): Indicates whether the tumor has spread to distant organs, such as bones and lungs.

Spread of remote organs

staging
0	Tis	N0	M0
I	T1	N0	M0
II	T0 or T1	N1	M0
II	T2	N0 or N1	M0
III	T0, T1 or T2	N2	M0
III	T3	N0, N1 or N2	M0
IVA	T4	any N	M0
IVA	Any T	N3	M0
IVB	Any T	any N	any N

Early-stage nasopharyngeal carcinoma has an extremely high cure rate, with a five-year survival rate of over 90% for stage I and II patients. However, because early-stage nasopharyngeal carcinoma lacks obvious symptoms, most patients are diagnosed at an intermediate or advanced stage. According to the latest data from the Hong Kong Cancer Registry, in 2018, approximately 40% of new nasopharyngeal carcinoma cases were diagnosed at stage III, and approximately 30% were diagnosed at stage IV.

Nasopharyngeal carcinoma spread rate

The rate of spread of nasopharyngeal carcinoma is related to the patient's condition and treatment. Generally, the closer to the late stage, the faster the spread of nasopharyngeal carcinoma. This is because when cancer cells grow to a certain size, they can invade nearby structures such as the throat, brain, and bones, but there is also a chance of spreading to other parts of the body. It is important to note that nasopharyngeal carcinoma develops very quickly, so early detection and treatment are crucial for improving the cure rate.

Once diagnosed, patients may need to undergo magnetic resonance imaging (MRI) to determine the extent of tumor involvement. Doctors may also arrange other appropriate imaging examinations, such as X-rays, CT scans, PET scans, and bone scans, depending on the individual patient's condition, to detect whether cancer cells have spread to other organs, thus enabling a detailed staging assessment. There are many treatment methods for nasopharyngeal carcinoma in Hong Kong. Before undergoing treatment, it is crucial to have the latest, most comprehensive, and accurate examinations, which are key to achieving the best treatment outcome.

Examination and diagnosis of nasopharyngeal carcinoma

Because of its hidden location, doctors need to use an endoscope to examine the nasopharynx for any abnormalities. If an abnormality is found, the doctor will take a tissue sample for pathological examination to determine if the abnormal tissue is nasopharyngeal carcinoma. This is called a "tissue biopsy." In addition, in Hong Kong, doctors also take blood samples from patients when treating nasopharyngeal carcinoma to measure the amount of EB virus antibodies and DNA in the serum.

IV. Treatment Methods

Radiotherapy

Radiotherapy is the primary treatment for nasopharyngeal carcinoma, applied regardless of the stage of the disease. It is a localized treatment that uses high-energy radiation to irradiate the tumor, killing the cancer cells. Early-stage nasopharyngeal carcinoma can be treated with radiotherapy as a radical cure, while later-stage carcinoma can be treated to alleviate symptoms caused by the spread of cancer cells, such as bone pain.

Radical radiation therapy typically lasts six to seven weeks, with patients usually receiving five treatments per week (Monday to Friday). The process is painless and requires no anesthesia or hospitalization. Before treatment, the radiation therapist creates a plastic mold based on the shape of the patient's head and face to stabilize the head and neck, ensuring accurate targeting of the radiation.

Radiation therapy technology

With advancements in technology, the latest radiotherapy techniques for nasopharyngeal carcinoma have evolved from conventional 2D radiotherapy to 3D conformal radiotherapy, and further to intensity-modulated radiotherapy (IMRT). IMRT is highly precise, delivering irregular radiation doses to the head and neck area. Doctors use computer programs to outline the tumor and adjacent organs and tissues to be avoided, such as the brainstem, spinal nerves, and salivary glands. They then calculate the optimal angle of incidence and radiation intensity, concentrating radiation on the tumor and minimizing damage to surrounding healthy tissues. The benefits of IMRT include a higher radiation dose to the tumor, improving treatment effectiveness, while minimizing the dose to surrounding tissues, thus reducing treatment-related side effects.

Side effects of radiation therapy

Side effects of radiation therapy can be categorized as short-term and long-term. Generally, short-term side effects tend to subside over time; however, long-term side effects may appear months or even years after treatment and may not subside, even worsening over time. Therefore, if patients are troubled by side effects that affect their daily lives, they should consult their doctor for relief and remedial methods to prevent the condition from continuing to deteriorate.

Chemotherapy

Chemotherapy typically delivers chemical drugs into the body via intravenous injection or oral administration. The drugs circulate throughout the body via the bloodstream, killing cancer cells; it is a systemic treatment. Chemotherapy is often combined with radiotherapy for mid-to-late-stage nasopharyngeal carcinoma to increase local control rates, reduce the chance of cancer cell spread, or delay the spread of cancer cells. Furthermore, for patients with local recurrence or those whose cancer cells have already spread, chemotherapy can control the tumor and alleviate symptoms.

The most commonly used chemotherapy drugs for nasopharyngeal carcinoma are cisplatin, carboplatin, and gemcitabine (5-FU), which can be used alone or in combination.

Preventive chemotherapy

Several weeks before radiation therapy, chemotherapy drugs are administered to shrink the tumor, which is then followed by radiation treatment. This is typically used for patients with large tumors to improve the success rate of local control and reduce the risk of cancer cells spreading to other organs.

Synchronous chemistry and radiation therapy

Radiation therapy combined with chemotherapy can enhance the local control rate of nasopharyngeal carcinoma and improve the survival rate of patients; however, the side effects of the treatment may be more severe.

Adjuvant chemotherapy

Chemotherapy is administered after radiotherapy to reduce the risk of cancer cells spreading to other organs and to reduce the chance of recurrence.

Surgery

Unlike other cancers, surgery is not the preferred treatment for nasopharyngeal carcinoma. This is because the nasopharynx is located deep in the center of the skull, very close to the base of the skull and many adjacent vital structures, such as the brain, cranial nerves, cerebral blood vessels, and the pituitary gland. Surgery could damage facial appearance and brain function. Furthermore, due to limitations imposed by brain structure, surgery may not achieve a sufficient safe margin, or, if there is concurrent deep lymph node metastasis, it may be difficult to completely remove cancer cells. Therefore, for nasopharyngeal carcinoma, surgery is only suitable in certain special cases, such as early local recurrence and recurrence in cervical lymph nodes.

For patients experiencing recurrent episodes, since they have already received a high dose of radiation during their initial episode, further radiation therapy could cause severe damage to local tissues, leading to more serious side effects and complications. In such cases, salvage surgery can save the patient from receiving further radiation therapy and the potential risks associated with it.

Surgical methods for nasopharyngeal carcinoma

The surgical approach for nasopharyngeal carcinoma depends on the location and size of the tumor. Smaller tumors located at the top of the nasopharynx can be removed using minimally invasive endoscopic surgery. Larger tumors require a maxillary swing approach, commonly known as "face-lifting surgery" in Hong Kong. This allows doctors to clearly observe the tumor and more easily access the nasopharynx with instruments, increasing the success rate of complete tumor removal. Currently, the maxillary swing approach is quite advanced; sutures are removed about a week after surgery, and most patients have no noticeable scars on their face. Post-surgery, patients need to receive physical therapy to stretch their oral muscles and massage their face to help speed up recovery. They should avoid eating hard foods and chewing vigorously with the teeth near the wound for six to eight weeks after surgery to prevent hindering wound healing.

For patients with recurrent cervical lymph nodes, radical neck dissection is necessary. In cases of extensive lymph node recurrence, after-loading brachytherapy is recommended after radical neck dissection.

In summary, although surgery is not the preferred treatment for nasopharyngeal carcinoma, it still plays a decisive role in saving patients who have failed local treatment or whose disease has recurred.

Notes after treatment

(1) Regular follow-up visits： After completing treatment, patients need regular checkups to monitor for recurrence and to manage any treatment-related chronic side effects promptly. Generally, doctors will perform regular blood tests and endoscopy, and schedule scans as needed. It is important to note that the symptoms of nasopharyngeal carcinoma recurrence are diverse and may differ significantly from the initial diagnosis; however, early local recurrence has a high cure rate, making timely and regular follow-up appointments crucial.

(2) Regular dental examinations： Because radiation therapy may damage the salivary glands, patients may experience reduced saliva production, which can easily lead to periodontal disease and cavities. Therefore, it is recommended that patients have regular dental checkups and maintain oral hygiene.

(3) Return to normal life as soon as possible： Although nasopharyngeal carcinoma treatment can be exhausting for patients, from a mental health perspective, returning to normal work and rest as soon as possible, where feasible, will benefit both the patient's physical and mental well-being.

(4) Regular work and rest to avoid overwork： After treatment, patients should maintain a normal work and rest schedule and try to avoid staying up late to keep their bodies in a balanced and healthy state.

(5) Perform rehabilitation exercises： Radiation therapy can cause fibrosis of the jaw and neck muscles, leading to jaw tightness and neck stiffness. Patients should consistently perform oral and neck rehabilitation exercises to improve their condition.

(6) Clean the nasopharyngeal cavity： Wash your nose regularly with saline or physiological saline to keep your nasopharynx clean and avoid rhinitis or sinusitis caused by unclean secretions.

If you need to find a nasopharyngeal carcinoma doctor in Hong Kong or learn about the latest treatment methods for nasopharyngeal carcinoma, please contact the United Cancer Centre Hong Kong.

FAQ

1. What are the main causes of nasopharyngeal cancer?

The exact cause of nasopharyngeal carcinoma is still unclear, but risk factors include family history, EB virus infection, excessive consumption of salted fish and pickled foods, and smoking.

2. What are the common symptoms of nasopharyngeal cancer?

Common symptoms include unilateral tinnitus, neck swelling, and bloody nasal discharge; in later stages, headaches and difficulty swallowing may occur.

3. Why is nasopharyngeal cancer spreading rapidly?

Because early-stage nasopharyngeal carcinoma has no obvious symptoms, most diagnosed patients are already in the middle or late stages, namely stages III and IV. Nasopharyngeal carcinoma spreads faster in later stages, making it a cancer that we need to pay special attention to.

4. What is the latest treatment for nasopharyngeal cancer?

The latest treatment for nasopharyngeal carcinoma is intensity-modulated radiotherapy (IMRT), which has the advantage of precisely delivering radiation to the tumor site and can enhance the effect when combined with chemotherapy.