Nasopharyngeal cancer

Overview

The nasopharynx is a tiny, tubular structure that links the nose to the oropharynx above the soft palate. Nasopharyngeal carcinoma (NPC), formerly known as lymphoepithelioma, is a kind of cancer that develops from the nasopharyngeal epithelium.

What is Nasopharyngeal cancer?

Nasopharyngeal carcinoma is a rare tumor that develops from the nasopharyngeal epithelium. It accounts for around 1% of all pediatric cancers. Whereas practically all adult nasopharyngeal tumors are carcinomas, only 35-50 % of pediatric nasopharyngeal cancers are. Additional nasopharyngeal cancers in children include rhabdomyosarcomas and lymphomas.

The clinical course of nasopharyngeal carcinoma depends on its histological subtype. Based on histology, the World Health Organization (WHO) has divided nasopharyngeal cancer into three subgroups. Type 1 is keratinizing squamous cell carcinoma, which is linked with EBV infection in around 70% to 80% of cases.

Type 2 nasopharyngeal cancer is differentiated non-keratinizing carcinoma, while kind 3 nasopharyngeal cancer is undifferentiated nonkeratinizing carcinoma, which is the most prevalent type. The latter two categories are also the most amenable to therapy. Almost all type 2 and type 3 cases are EBV-related and occur in areas where EBV is prevalent.

Nasopharyngeal carcinoma with basaloid characteristics is a newer, uncommon histologic group that has been linked to aggressive behavior. Treatment is not differentiated based on histologic subtypes. In general, nasopharyngeal cancer mortality has decreased in the recent decade as a result of earlier identification and treatment breakthroughs.

Anatomy of Nasopharynx

The upper part of the pharynx (throat) behind the nose is known as the nasopharynx. The pharynx is a 5-inch-long hollow tube that begins below the nose and finishes at the top of the trachea (windpipe) and esophagus (the tube that goes from the throat to the stomach). On their path to the trachea or the esophagus, air and food travel via the pharynx. The nostrils are the entrance points to the nasopharynx. An ear is reached by an aperture on each side of the nasopharynx. Most nasopharyngeal cancers begin in the squamous cells that border the nasopharynx.

How prevalent is nasopharyngeal carcinoma?

Nasopharyngeal carcinoma (NPC) is quite common among Southern China, Malay and Indonesian populations, as well as Southeast Asians. The rate ranges from fewer than one per 100,000 people in non-endemic areas to a maximum of 25 to 30 and 15 to 20 men and girls per 100,000 people in endemic areas, respectively.

What are causes of Nasopharyngeal carcinoma?

The disease's origin involves an interaction of environmental variables, genetic structure, and EBV infection. Environmental variables, such as smoking in the Western population and nitrosamine-containing dietary ingredients, have been implicated. Second, the genetic structure of the populations involved is important, as seen by the high prevalence in the Chinese community. Finally, EBV infection, in conjunction with genetic vulnerability, has demonstrated a significant significance to the illness. 

Nasopharyngeal cancer Symptoms

Patients can have variable presentations depending on the area of involvement of the disease.

• Nasal symptoms: Nasal symptoms range from nasal blockage, blood-tinged nasal discharge, and post-nasal drip to denasalization of voice and cacosmia in a subgroup of individuals. The severity of symptoms is proportional to the size of the growth and the level of local involvement. Approximately 80% of those suffering from the condition have nasal symptoms.
• Otological symptoms: Patients appear with conductive hearing loss, effusions and fullness, and tinnitus as a result of eustachian tube obstruction. During the illness, half of the patients with NPC have some sort of otological complaint caused by the increasing mass impeding the outflow of the eustachian tube.
• Neurological symptoms: Intracranial extension affects 8% to 12% of the population, with various kinds of cranial nerve involvement presenting with the related symptom. The abducens nerve is the most usually affected nerve. 
• Nodal involvement: An enlarged neck node is one of the most prevalent presenting characteristics. Initially, the lymph nodes at the apex of the posterior triangle and the upper jugular are most usually affected. Supraclavicular nodes are the last to be affected and indicate severe illness. 

Distant metastasis and paraneoplastic syndrome:

Symptoms of distant spread are seldom seen by the main caregiver. The liver and lungs are the most often affected organs. When metastatic pulmonary lesions emerge, it might be difficult to determine the initial location of the cancer. A PET scan can help distinguish between the two. Second, a few instances manifest with dermatomyositis symptoms. The disease may develop as a result of the malignant tumor or after the first diagnosis of NPC.

Nasopharyngeal cancer Diagnosis

Imaging procedures of the nose and throat aid in the diagnosis of nasopharyngeal cancer. The process of determining whether cancer cells have spread to other places of the body is known as staging. Before beginning therapy, tests and procedures to identify, diagnose, and stage nasopharyngeal cancer are performed.

The following tests and procedures may be used:

• Physical exam and health history: An examination of the body to look for general symptoms of health, such as enlarged lymph nodes in the neck or anything else that appears strange. A history of the patient's health habits, as well as previous diseases and treatments, will be collected.

• Neurological exam: A sequence of questions and tests to assess the function of the brain, spinal cord, and nerves. The test assesses a person's mental state, coordination, and ability to walk normally, as well as the function of the muscles, senses, and reflexes. This is also known as a neuro exam or a neurologic exam.

• Biopsy: The excision of cells or tissues so that a pathologist may examine them under a microscope for symptoms of malignancy. The tissue sample is extracted using one of the following methods:
  • Nasoscopy: A technique that examines the interior of the nose for abnormalities. Through the nose, a nasoscope is inserted. A nasoscope is a narrow, tube-like tool with a viewing light and lens. It may also include an instrument for extracting tissue samples, which are then examined under a microscope for symptoms of malignancy.
  • Upper endoscopy: An examination of the interior of the nose, throat, esophagus, stomach, and duodenum (first part of the small intestine, near the stomach). An endoscope is placed into the esophagus, stomach, and duodenum through the mouth. An endoscope is a narrow, tube-like tool with a viewing light and lens. It might also include a tool for removing tissue samples. Under a microscope, the tissue samples are examined for symptoms of malignancy.

• Magnetic resonance imaging (MRI): A technique that use a magnet, radio waves, and a computer to create a sequence of detailed images of locations within the body. This method is also known as nuclear magnetic resonance imaging (NMRI).

• CT scan: A method that takes a series of detailed photographs from various perspectives of locations within the body, such as the chest and upper abdomen. A computer coupled to an x-ray machine creates the images. To make the organs or tissues more visible, a dye may be injected into a vein or ingested. This is also known as computed tomography, computerized tomography, or computerized axial tomography.

• PET scan (positron emission tomography scan): A method of locating malignant tumor cells in the body. In a vein, a little quantity of radioactive glucose (sugar) is injected. The PET scanner revolves around the body, capturing images of where glucose is utilized. Because malignant tumor cells are more active and take up more glucose than normal cells, they appear brighter in the image. PET scans can detect nasopharyngeal cancer that has migrated to the bone. A PET scan and a CT scan are sometimes performed at the same time. This raises the likelihood that cancer may be discovered.

• Ultrasound exam: High-energy sound waves (ultrasound) are rebounded off organs in the abdomen, creating echoes. The echoes combine to generate an image of bodily tissues known as a sonogram. The image can be printed and viewed later.

• Chest x-ray: An x-ray shows the internal organs and bones of the chest. An x-ray is a form of energy beam that may go through the body and onto film to create an image of places within the body.

• Blood chemistry studies: A method in which a blood sample is examined to determine the levels of specific compounds produced into the blood by the body's organs and tissues. A chemical in an unusual (higher or lower than normal) concentration might be a symptom of the disease.

• Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
  • The number of red blood cells, white blood cells, and platelets.
  • The amount of hemoglobin in the red blood cells.
  • The portion of the blood sample made up of red blood cells.

• Epstein-Barr virus (EBV) test: A blood test to look for antibodies to the Epstein-Barr virus and Epstein-Barr virus DNA markers. These are discovered in the blood of EBV-infected people.

• HPV test (human papillomavirus test): A laboratory test that checks a tissue sample for particular forms of HPV infection. This test is performed because HPV can cause nasopharyngeal cancer.

• Hearing test: A process for determining whether quiet and loud noises, as well as low and high-pitched sounds, may be heard. Each ear is examined individually.

Nasopharyngeal cancer Management

Because the non-keratinizing form is extremely radiosensitive, radiation is the basis of treatment for NPC in locoregional lesions. In advanced stages, surgical intervention is limited to salvage surgeries in recurring illnesses, whereas chemotherapy is favored together with radiotherapy.

• Radiotherapy

Radiation is the preferred treatment for a loco-regional lesion. Except for distant metastases, radiotherapy is successful in all instances from stage I to stage IVB. NPC has a proclivity for rapid regional spread, especially because the nasopharynx is a tiny cavity, making dissemination to paranasopharyngeal spaces, muscles, and nodes frequent. Furthermore, gradual involvement of the contralateral side is not uncommon. As a result, a dosage of roughly 65 Gy for main tumors and 50 to 55 Gy for nodal negative necks is required.

Intensity modulation, often known as intensity-modulated radiotherapy, is a new advancement in the radiation delivery method (IMRT). The technology includes a CT scanner that takes slices of the affected region. The physician determines the beam's targeted region and controls the strength of the beam used.

Brachytherapy is another novel approach to focused radiation. The gold grains or iridium implants are inserted through a soft palate split incision and jacketed for targeted irradiation. The procedure is beneficial for circumscribed tumor masses with minimal cerebral extension. The method avoids any local organ damage.

When a treatment fails or a recurrence occurs, radiotherapy is used. It has been shown to be effective in both local recurrence and nodal failures. In such circumstances, brachytherapy is considered while keeping the friability of the local tissue, the patient's overall state, and the influence on essential organs in the region in mind.

• Chemotherapy

NPC is extremely vulnerable to radiation and chemotherapy. Concomitant chemoradiotherapy is the basis of treatment for locally advanced regional illness. The illness responds better to induction, and concomitant treatment has a considerable impact on tumor bulk reduction. Cisplatin is the most often utilized drug as the first line of chemotherapeutic intervention. A dosage of 100 mg every third week is the mainstay of therapy.

When distant metastasis is present, chemotherapy is also a possibility. Palliative chemotherapy is given to NPC with distant polymetastasis. Cisplatin and 5-fluorouracil are the preferred agents. With recent breakthroughs, various chemotherapeutic drugs are now accessible for treatment continuation. The median survival rate, however, is less than a year.

Surgical Intervention

Surgical intervention is only used as a last resort. Because the nasopharynx is a tiny and deep region that is difficult to access, surgical approaches to it are sometimes challenging and unsuitable. Patients should be given the option of surgical surgery if they have the locally recurrent illness. Surgery, in combination with radiation and radio ablation, is also an important modality of treatment for distant oligometastasis.

Transoral laser microsurgery can be used if the tumor is tiny. The laser is mounted atop a tiny metal scope (tube). Before the procedure, the patient is given anesthetic. The laser is put into the mouth, and the laser beam is utilized to remove the tumor as well as one centimeter (2.5 inches) of tissue surrounding it.

Because the patient cannot eat until the surgical region heals, a tiny nasogastric feeding tube (NG tube) is put via the nose and into the stomach. Healing time is around two weeks. During this period, the patient will be fed through an NG tube with liquid meals. Three to five days following surgery, the patient can go home with the NG tube in his or her nostril.

Larger tumors necessitate a typical scalpel incision. Before the procedure, the patient is given an anesthetic. To find and remove the tumor, the surgeon makes an incision in the neck, beneath the chin. The exposed region is subsequently closed by a flap of skin or muscle from the arm or another portion of the body.

If the lymph nodes in the neck are impacted, they may need to be removed by neck dissection.

Staging

The American Joint Committee on Cancer (AJCC) has reevaluated the staging procedure due to advancements in imaging tools and improved results linked with optimal treatment. According to the most recent recommendations, TNM staging is stated as follows:

Primary Tumor (T):

• Tx: Inability to assess the tumor.
• T1: Nasopharyngeal involvement sparing the parapharyngeal spaces
• T2: Extension into the parapharyngeal spaces and may or may not extend into regional muscles (Pterygoids and prevertebral)
• T3: Invasion of skull and sinuses
• T4: Intracranial extension with the involvement of Cranial nerves, pterygoids, and orbit.

Nodal metastasis (N):

• NX: Inability to assess nodal involvement
• N0: No involvement
• N1: A unilateral spread not exceeding 6 cm in maximum dimensions confined above supraclavicular fossa
• N2: A bilateral spread not exceeding 6 cm in maximum dimensions confined above supraclavicular fossa
• N3: Metastasis
• N3a: involvement greater than 6 cm
• N3b: supraclavicular fossa involvement

Distant Metastasis (M):

• MX: Inability to assess metastasis
• M0: No distant involvement
• M1: Distant Involvement.

Stage grouping:

• Stage 0: T1s-N0-M0
• Stage I: T1-N0-M0
• Stage II: T1-N1-M0 and T2-N0-M0 
• Stage III: T1, T2-N2-M0 and T3-N0, N1, N2-M0
• Stage IVA: T4-N0, N1, N2-M0
• Stage IVB: Any T-N3-M0
• Stage IVC: Any T-Any N-M1

Prognosis

Since the introduction of subtleties in radiation procedures, the overall prognosis and 5-year survival rate have improved. In the last decade, the mortality and morbidity associated with sickness have declined dramatically, from a reported 5-year survival rate of 25% to 40% to roughly 70%.

Nasopharyngeal cancer Complications

Local consequences of lesions include occlusion of the Eustachian tubes, which causes otitis media with effusion (OME), chronic nasal obstruction, and obstruction of the oropharyngeal airway. The mass effect that causes oropharynx obstruction impedes swallowing and, if left uncontrolled, may lead to airway blockage. Intracranial extension and cranial nerve involvement are debilitating and can result in permanent impairment even after treatment.

Conclusion 

Nasopharyngeal cancer (NPC) is A kind of head and neck cancer. It begins in the nasopharynx, which is the top region of the throat behind the nose and close to the base of the skull. NPC is distinct from other head and neck cancers in terms of incidence, etiology, clinical behavior, and therapy. It is far more frequent in specific parts of East Asia and Africa than elsewhere, and it is thought to be caused by viral, nutritional, and genetic factors. 

It is an undifferentiated squamous cell cancer. Squamous epithelial cells are flat cells found in the skin and the membranes that border some bodily cavities. Differentiation refers to how distinct cancer cells are from normal ones. Undifferentiated cells are those that lack mature characteristics or functions.