Learn About Nasopharyngeal Cancer(NPC)

There are around 900 rising cases of NPC in Hong Kong every year. NPC is, currently, becoming one of the local common cancers. The incidence rate of NPC for males is 3 times higher than that for females. In 2015, NPC was the 6th commonest cancer in men and 14th in women. The peak age for NPC incidence is around 50 to 60 which is younger than that of other cancers.

 

Although NPC is one of the common cancers, its impact on human is being reduced as a result of technological advances. From the cancer registry statistics, it reads that the incidence rate and mortality rate of NPC have been showing a decreasing trend in recent years. The higher cure rate is found if NPC is discovered at the early stage. The cure rate of stage I NPC can reach over 90%, implying high treatment efficacy of NPC.

 

Source: Hong Kong Cancer Registry(2015).

 

Structure of Nasopharynx

Nasopharynx locates at the central region of the head. It is the space above the soft palate and at the back of the nose and connects the nose to the mouth. The surrounding tissues involve brainstem, pituitary gland, cranial nerves and Eustachian tube. Since its location is hidden, the endoscopic assessment is required for checking the structure. NPC is the carcinoma originated from nasopharynx. The carcinoma will duplicate and oppress neighboring organs. Cancer cells may even travel to other parts of body through the bloodstream or the lymph system.

 

 

Cause of NPC

NPC comes with malignant transformation of surface cells in the nasopharynx but the exact cause is not readily apparent. Multiple factors confer to the NPC risk are commonly agreed by medical professionals.

 

Heredity: First degree relatives of NPC patients such as biological parents, siblings and children are exposed to a higher risk of suffering from NPC than others.

 

Epstein-Barr Virus(EBV): People with EBV infection may show no symptoms or only show symptoms similar to that of common cold. Several studies have reported that a high level of EBV antibodies are found in blood serum of patients with NPC, but the further investigation is required.

 

Diet: Geographically, NPC is prevalent in Southern China and more common there than in many other countries. It is, therefore, also named as “Guangdong Cancer”. It is believed that the high prevalence is related to the dietary habits of consuming salted fish and other pickled food which contain nitrosamine carcinogens.

 

Other factors: Exposure to the working environment with high level of wood dust, formaldehyde or chemical perfume, frequently burning joss sticks and inhaling the fume, and defeated immune system may probably increase the risk.

 

Symptoms of NPC

Since the location of nasopharynx is hidden, symptoms may not be apparent at the early stage. However, the following symptoms may be present with the enlargement and metastasis of cancer cells. Swelling of neck lymph nodes is the common symptom of NPC.

 

Other symptoms:

Stuffiness and running nose

Nose bleeding

Blood stained sputum

Tinnitus

Hearing loss

Headache

Double vision

Facial paralysis

Hoarseness

Swallowing difficulty

 

NPC Prevention

Having a healthy lifestyle such as limiting processed food or pickled food intake can help prevent NPC. Wearing appropriate protective equipment, including dust facial mask can reduce direct contact with carcinogens. You should seek help from medical professionals if you suspect yourself having early symptoms of NPC. Regular body check is strongly suggested if you are in high risk groups.

 

Diagnosis

Regular body checking and seeking help from doctor can help diagnose and treat NPC at the very early stage. Earlier NPC being detected, higher the cure rate. The following shows the examinations of NPC.

 

Nasal endoscopy: Doctor will insert an endoscope with fiberoptic camera through nostrils into nasopharynx. It can help check any visible abnormality of the structure.

 

Biopsy: If doctor finds the abnormal area in nasopharynx through nasal endoscopy, doctor may remove a little piece of biopsy sample for laboratory investigation on the pathology.

 

Blood test: To detect the level of EBV antibodies in blood serum.

 

Once paitents are diagnosed with NPC, the following investigations will be arranged for determing the cancer stage, locating the accurate tumor site and metastasis.  

 

MRI

CT scan

Ultrasound scan

Chest X-ray

PET scan

 

Staging of NPC

Staging of NPC is used to present the extent of metastasis and predict the cure rate for doctors to tailor a suitable treatment plan for individual patient. The staging used is cited from American Joint Committee on Cancer(AJCC).

 

Stage 0

Tumor is in situs and only in the top layer of cells lining the inside of the nasopharynx.

Stage I

Tumor is localized in nasopharynx.

Stage IIA

Tumor might have grown into oropharynx and nasal cavity. The tumor has not spread to distant parts of the body.

Stage IIB

The tumor has grown into the tissues of the either sides of the upper part of the throat. OR the tumor has spread to lymph nodes on the neck. The tumor has not spread to distant parts of the body.

Stage III

The tumor is found in lymph nodes in the neck.The tumor has not spread to distant parts of the body. OR the tumor has grown into the sinuses or the bones nearby.

Stage IVA

The tumor is found in skull and/or cranial nerves, but the cancer has not spread to distant parts of the body.

Stage IVB

The cancer has spread to distant parts of the body.

 

Survival Rate

Around 80% to over 90% of survival rate for stage I to III NPC. Around 70% for stage IV.

 

Treatment

Due to the hidden area of NPC, the surgical excision of tumor is rarely performed to treat the disease. The appropriate treatment of NPC is, otherwise, always radiotherapy. Patients with stage IV, III and sometimes II NPC may be suggested to undergo radiotherapy and chemotherapy at the same time, in order to enhance the sufficient therapeutic effect. Sometimes, radiotherapy followed by chemotherapy or vice versa may be suggested accordingly.

 

Radiotherapy

Radiotherapy uses high doses of radiation to destroy cancer cells. Patients will not feel painful during the procedure. No anaesthesia or admission to hospital or isolation for radiation is needed. The whole treatment course takes around 6 to 8 weeks and patients will have radiotherapy session nearly every day.

 

Nowadays radiotherapy uses three-dimensional conformal and intensify modulated technology to treat NPC. Before the radiotherapy, since radiation will affect salivary secretion, patients will have oral examination and tooth problems will be fixed beforehand if any. Radiotherapist will make a plastic mould of patients’ head for use of holding head and concentrating radiation beams at the tumor accurately. Patients also need to undergo CT for presenting the tumor and nearby tissues in 3D images. Highly precise intensity and shooting angle of radiation will be calculated for concentrating radiation at the tumor and minimizing impact on nearby tissues and side effects.    

 

Patients undergoing radiotherapy may show side effects of nausea, dry mouth, mouth sore, change in taste, decreased appetite, dry skin and hair loss. In long term, patients may have ear inflammation which can have potentially serious consequences such as hearing loss. Patients can also experience jaw stiffness and hormone imbalance. 

 

 

Chemotherapy

Some medication will be given by intravenous injection, allowing medicine travelling to different body parts and killing cancer cells. Difference in order of performing radiotherapy and chemotherapy can vary in treatment efficacy. Giving radiotherapy and chemotherapy at the same time works better. Doctor will tailor treatment plan according to each patient’s need.

 

 

 

References

http://www21.ha.org.hk/smartpatient/SPW/en-us/Disease-Information/Cancer-In-Focus/Details/?guid=03bd3c50-ca5a-4399-a929-7445b96c4696

http://www3.ha.org.hk/cancereg/

https://www.chp.gov.hk/en/healthtopics/content/25/54.html

(Chinese only) https://www.hkacs.org.hk/ufiles/NasopharyngealCarcinoma.pdf