Objective: To investigate the relationship between changes in high-risk populations and screening detected nasopharyngeal carcinoma (NPC) during the three-year follow-up of high-risk and moderate-risk groups at initial EB virus serology screening.
Methods: We tested EB virus VCA-IgA and EBNA1-IgA antibody to identify the probability of suffering from NPC of the crowd. The high-risk and moderate-risk groups at initial screening in one county during 2009 to 2010 were followed-up once a year with EB virus serology testing. All the high-risk people during initial screening and follow-up were conducted with nasopharyngeal fiber endoscopy. Through the follow-up of three years, we analyzed changes in the number of high-risk group, detection rate of NPC in high-risk group, and tumor staging. Firstly detected NPC by screening was defined as screening group, and detected by following-up was defined as following-up group.
Results: A total of 404 participants were at high-risk and 1 041 participants were at moderate-risk group, 1 445 persons were in the group. All 404 persons were at high-risk at initial screening, the number of high-risk people during follow-up decreased from 371 to 187, 853 people of the all high-risk group were conducted with nasopharyngeal fiber endoscopy, and 38 cases of NPC were detected. NPC detection rate of high-risk group was 6.2% (25/404), 3.2% (12/371), 0.5% (1/188) and 0 (0/187) during the initial screening and three years follow-up respectively. The cumulative incidence of NPC in the high-risk and moderate-risk group were 7.7% (31/404) ,0.8% (8/1 041) . The early diagnosis rate of NPC in screening group and following-up group was 80% (20/25)and 11/13, respectively. With the primary tumor, the rate of T1 in screening group was higher than following-up group (80% to 38%, 20/25 to 5/13; P = 0.028). However, compared with following-up group, the rate of regional lymph node metastasis in screening group was higher (19/25 to 5/13; P = 0.035 ).
Conclusion: Along with the high detection rate of early staging NPC in screening group and following-up group, the detection of NPC in high risk people is mainly at initial screening and the first year following-up and NPC detection rate thereafter is dropping significantly.