Human papillomavirus in non-small cell lung cancer in never smokers in east Asia: A systematic review of the literature.

Abstract

e18128 Background: Non-small cell lung cancer (NSCLC) in never-smokers has emerged as a global health concern, but its cause is undetermined. Epidemiological studies have shown that the disease is frequently observed in East Asia. Human papillomavirus (HPV) infection has been widely investigated in NSCLC, particularly in Asia. However, few studies have focused on regional differences in the prevalence of HPV in NSCLC tissue from never smokers. Methods: We performed a systematic search of PubMed for articles of HPV infection in human subjects with NSCLC between Jan. 1993 and Dec. 2011. We included studies that used polymerase chain reaction (PCR) as the primary HPV detection method. Because smoking status was not fully reported in all studies, we contacted the authors by e-mail to supplement this information. Differences in the distribution of patients with and without HPV infection were tested with the Chi squared test. Results: We identified 42 eligible articles, including 21 from Asian countries (N=2095 NSCLC cases), 17 from European countries (N=1430) and 4 from North and South America (N=160). The HPV prevalence was 28.0% (95% confidence interval (CI): 26.1-30.0%), 8.7% (95% CI: 7.3-10.3%) and 21.2% (95% CI: 15.2-28.4%), respectively. Seven studies from East Asia (N=939) and 4 from Europe (N=569) provided information on smoking status. The number of never smoker was 314 patients (33.4%) in East Asia and 54 patients (9.5%) in Europe. The HPV prevalence in East Asian countries was similar between never and ever smokers (38.2% vs 39.5%, P=0.94) and was significantly higher compared with European countries, where the prevalence was14.8% in never smokers (P<0.001) and 2.9% in ever smokers (P<0.001). In East Asia, the HPV prevalence was particularly high in Taiwan, the central part of China and Okinawa, south of mainland Japan. Conclusions: The prevalence of HPV is high in NSCLC tumor tissues from East Asia. Although the numbers of never smokers from European studies are very small, the different patterns of HPV prevalence from Asian and European countries is intriguing and deserves further study.