Nasopharyngeal Carcinoma (NPC)
Nasopharyngeal Carcinoma (NPC) is one of the leading causes of cancer deaths among ethnic Asian groups. Chinese individuals from Southern China have the highest risk in developing NPC. Statistics have shown that males are affected much more frequently than females with a life-time risk for developing NPC of 1 in 53 men compared to 1 in 131 women. NPC has a peak incidence in the 50 to 54 age range, with an incidence rate that starts to climb steadily to this point after 15-20 years of age. The annual mortality, or death rate, for this cancer exceeds 50,000 annually which is a tragic statistic because NPC can be cured when detected early.
Where is NPC endemic?
NPC is highly prevalent in the southern parts of China (30-250 per 100,000) including major cities like Hong Kong and Guangdong, accounting for 18% of all cancers in China. Intermediate incidence rates are found in Southeast Asia, the Mediterranean rim countries, coastal regions of Africa, and in the aboriginal populations of Alaska and Greenland. Large population of emigrants relocating from endemic areas to non-endemic areas such as United States, Canada and Europe also maintain their elevated risk status.
Where is NPC located in the human anatomy?
NPC is the most common cancer originating in the nasopharynx, the uppermost region of the pharynx (“throat”), behind the nose where the nasal passages and auditory tubes join the remainder of the upper respiratory tract.
EBV and NPC
The Epstein-Barr virus (EBV), also called human herpesvirus 4 (HHV-4), is a virus of the herpes family, and is one of the most common viruses in humans. It is best known as the cause of infectious mononucleosis (mono or glandular fever). EBV infection normally occurs in early childhood.
The association between EBV infection and NPC is well documented and cells with EBV genome are present in virtually all NPC cells. Epstein–Barr virus (EBV) was classified by the International Agency for Cancer Research (IARC) as a Class I carcinogen for NPC in 1997. Both the World Health Organization (WHO) and American Joint Committee on Cancer (AJCC) have classified it as one of the earliest forms of cancer, carcinoma in-situ (Stage 0), with the presence of Epstein-Barr virus (EBV) DNA in the cancer cell.
Although 95% of the adult population worldwide may be infected at some time in their lives with EBV. The genesis of NPC is multifactorial; the presence of EBV is crucial to the formation of NPC but it is not the only cause. Currently, it was confirmed that many factors can result in the activation of EBV, such as environmental carcinogens, genetic and/or immune deficiency.
EBV is an extremely good marker for NPC detection. Utilizing EBV and creating a highly accurate screening test will change the landscape of NPC, especially, for people with a family history of NPC, whereby their risk of having NPC can be 20 times higher.