Nasopharyngeal carcinoma (NPC) is a malignant tumor of the nasopharynx and one of the most common carcinomas in China, the incidence of which is increasing year by year, seriously endangering people’s health.
1.Epidemiological characteristics Obvious geographical differences. The incidence of nasopharyngeal cancer is high in southern China and Southeast Asia, while it is rare in Europe and America, accounting for only 1%-2% of systemic malignant tumors. The incidence rate of nasopharyngeal cancer in China is higher in the south than in the north, and higher in coastal than in mountainous areas. Guangdong, Guangxi, Fujian, Jiangxi, Hunan, Guizhou and Taiwan provinces have high incidence rates, especially in the Pearl River Delta and Xijiang River basin in Guangdong, and Zhaoqing is a high incidence area in Guangdong Province, accounting for the top of malignant tumors, while the north occupies the eighth place. Obvious racial differences. Nasopharyngeal cancer is more common in yellow race, such as Chinese, Indonesians, Malaysians, Thais, Vietnamese, Filipinos, etc.. It is rare in Caucasians, and rare in Blacks except Kenyans. The incidence is also much higher among foreign Chinese and mixed-race children of Chinese ancestry than among locals. There is a clear tendency for it to occur in families. According to a typical family, 9 out of 49 people in three generations had nasopharyngeal cancer, all of whom were maternal relatives. Obvious gender differences. There are more men than women, about 3-6:1, whether it is related to more men smoking is yet to be studied. The age of onset is reported to be 3-86 years old, and 2/3 of the cases occur in people aged 30-49 years old, less than 20 years old or more than 60 years old, but in recent years, the age of onset has a tendency to be younger.
2.Etiology The exact cause is not known, but the following factors may be related: ① Genetic factors. Nasopharyngeal cancer has racial and familial susceptibility, which is presumed to be related to genetics, racial specificity and anatomical characteristics of nasopharynx.
②Environmental factors. The geographical distribution of nasopharyngeal cancer seems to be related to the natural environment, water quality, living conditions, people’s habits and dietary habits of the region. Some people fed mice with Guangdong salted fish with high content of dimethylnitrosamine, which induced nasal carcinoma in mice after 1 year. Nickel is a recognized carcinogenic substance and its role in the etiology of nasopharyngeal cancer needs further study.
(iii) Biological factors. The viral theory of nasopharyngeal carcinoma has been widely emphasized. In 1970, Henle’s found 100 nm diameter particles in nasopharyngeal carcinoma cells, similar to Epstein-Barr adenovirus. It has been widely reported that the titer of anti-EB virus shell antigen immunoglobulin A (VCA-IgA) in the serum of almost 10,000 patients with nasopharyngeal carcinoma was significantly increased. This suggests a close relationship between nasopharyngeal carcinoma and EBVs, but it is inconclusive whether EBVs are oncogenic factors or “transient symbionts”.
④Smoking. The health hazards of smoking have become a worldwide concern. The stimulation of large amount of burning smoke and the benzene ratio in the tar of tobacco can cause mucosal congestion, edema, epithelial thickening and squamous metaplasia, which may be the basis of carcinogenesis.
3.Clinical manifestations Nasopharyngeal pain usually occurs in the pharyngeal fossa, the bulge of pharyngeal tube and the posterior wall of nasopharyngeal apex. Few of them are at the posterior edge of nasal septum, back of soft consternation and lateral wall of nasopharynx.
Seven symptoms of nasopharyngeal cancer: ① Retracted snot with blood. It is often the only early symptom. Retracted snot with blood means snot with blood exhaled from the nasopharynx after nasal aspiration. In early stage of nasopharyngeal cancer, there may be erosion or ulcer on the surface, and a small amount of blood is leaked out. Bleeding from acute inflammation of the nasopharynx mostly occurs when coughing vigorously in the pharynx; bleeding from the nasal septum in the Richter area is mostly caused by nose digging; bleeding from sinus tumors or mycobacterial infections is mostly blood mixed with pus snot when blowing out; however, nasopharyngeal cancer can also bleed heavily in the advanced stage, which requires extra attention.
② Symptoms of non-suppurative otitis media. The cancer in the pharyngeal fossa or the bulge of the eustachian tube can cause negative pressure in the middle ear, resulting in ipsilateral tinnitus, ear congestion and conductive deafness, sometimes accompanied by ear pain, and otoscopic examination can reveal tympanic membrane invagination or tympanic chamber effusion.
(3) Headache Almost every patient with nasopharyngeal carcinoma has different degrees of headache. In the early stage, the cancer tumor stretches or compresses the trigeminal nerve endings in the nasopharyngeal mucosa, causing continuous vague pain in the temporoparietal-occipital area on one side (the same side as tinnitus).
(4) Upper neck mass. Nasopharyngeal carcinoma can metastasize to the deep upper cervical lymph nodes at an early stage, and the incidence is as high as 27%-83%. This group of lymph nodes is located on the deep surface of the superior sternocleidomastoid muscle or below the tip of the mastoid process. They can also be located in the deep posterior abdominal layer of the biceps muscle and the anterior border of the oblique muscle. In advanced stages, there may be supraclavicular lymph node metastases. The metastasis is often to one side of the neck, and in cases where the primary focus is in the midline of the nasopharynx, bilateral cervical lymph node metastasis may occur. The mass is painless, hard, and poorly mobile, and may rapidly increase in size and fuse into a large mass and become fixed.
⑤ Nasal congestion. Except for the early nasal congestion of carcinoma around the posterior nostril, nasal congestion is usually a symptom in the middle stage, which is caused by the growth of carcinoma blocking the posterior nostril.
(6) Symptoms of cranial nerve involvement.
4.Diagnosis Early diagnosis and early treatment of many patients can obtain unclamped effect.
Diagnostic methods: Electronic nasopharyngoscopy, CT of nasopharynx, MRI, nasopharyngeal biopsy, screening can be sent for EBV antibody test, and final diagnosis requires nasopharyngeal biopsy.