Etiology and early detection of nasopharyngeal carcinoma : an epidemiological approach

• Main Author: Liu, Zhiwei
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Inst för medicinsk epidemiologi och biostatistik / Dept of Medical Epidemiology and Biostatistics 2016
• Subjects: Arctic
• Online Access: http://hdl.handle.net/10616/45210

Nasopharyngeal carcinoma (NPC) is a rare malignancy worldwide, but it is endemic in a few areas including southern China, Southeast Asia, North Africa, and the Arctic. The underlying mechanisms behind this remarkable geographic distribution remain unclear. Although Epstein-Barr virus (EBV) infection has been suggested as a necessary cause of undifferentiated NPC, EBV itself is not sufficient to cause this malignancy. Other co-factors, such as environmental risk factors, and/or genetic susceptibility, may interact with EBV to play a role in the carcinogenesis of NPC. Survival rates differ significantly between NPC patients in early stages and late stages. Due to the close associations between EBV infection and NPC risk, EBV-related biomarkers have been used for early detection and screening for NPC has been conducted in a few high-incidence areas. However, the cost-effectiveness of this approach has not been demonstrated. Pilot efforts have highlighted that identification of additional biomarkers is needed to improve early detection rate and reduce the mortality rate of NPC in high-incidence populations. The aim of this thesis is to study the association of early-life social environment, oral hygiene, and family history with the risk of NPC, and to utilize an affinity proteomic approach to identify biomarkers that can potentially facilitate the early detection. In Study I, we investigated associations between childhood family structure, in terms of sibship size and number of older/younger siblings, and the risk of NPC or infectious mononucleosis (IM, another EBV-associated disease) in Sweden, an NPC low-incidence area. For each outcome, a nested case-control study was conducted within the Swedish national health and population registers, including 251 NPC cases, 11,314 IM cases, and five population controls per case matched by sex and year of birth. Clearly contrasting findings were observed between NPC and IM risk. We detected a monotonically increased risk of NPC with a larger sibship size (P trend = 0.006), ...