Screening of nasopharyngeal carcinoma by serology and nasopharyngoscopy and treatment outcome in endemic region

Abstract

6029 Background: To study the incidence and treatment outcome of nasopharyngeal carcinoma (NPC) detected by serology and nasopharyngoscopy in endemic region. Methods: A prospective screening program for NPC using Epstein-Barr virus-specific viral capsid antigen IgA antibody level and nasopharyngoscopy was carried out in Southern China from 1996 to 2002. Subjects without NPC at the time of enrollment were followed-up annually by serology and clinical examination irrespective of their serology status. Subjects diagnosed to have NPC at the time of enrollment or during follow-up received conventional radiotherapy using megavoltage photon. Results: A total of 42,048 adults in Zhongshan city of China were enrolled into the screening program. About 7.4% had elevated IgA titre at the time of enrollment. NPC was diagnosed at first screening in 40 subjects and during follow-up in 131 subjects. Among the 171 NPC patients, 74 were asymptomatic and the disease was detected by the screening procedures, whereas the disease was detected in 97 following onset of symptoms. Stage distribution in those diagnosed by screening program was 59.5% stage I, 8.1% stage II, 21.6% stage III, and 10.8% stage IV. The corresponding stage distribution in subjects diagnosed after onset of symptoms was 7.2%, 12.4%, 39.2%, and 41.2%. In all NPC patients the IgA titre was found elevated and there was a serologic window in which the raised titre preceded the diagnosis of NPC for a period of up to 10 years. The median interval of this serologic window was 29 months in patients with stage I NPC and 39 months in those with stage II-IV disease. The 5-year disease-specific survival rate was 90% for stage I disease, 56% for stage II, 48% for stage III, and 52% for stage IV. Conclusions: Screening by serology and nasopharyngoscopy leads to the early diagnosis of NPC in endemic region with a high survival rate after treatment for stage I disease. In view of the rapid transition of disease from stage I to more advanced stage, a screening interval shorter than 10 months is recommended for subjects entering the serologic window. No significant financial relationships to disclose.