A Survey in Liangshan, Sichuan Showed Higher Human Papillomavirus Infection Rate and Cervical Cancer Risk for Yi Chinese Compared to Han Chinese

Background: Human papillomavirus (HPV) is a sexually transmitted virus reported to be strongly correlated to the development of cervical cancers. An ethnic minority in Liangshan, Sichuan known as Yi Chinese were reported to be more susceptible to sexually transmitted virus, such as the human immunodeficiency virus. However, the prevalence of HPV and cervical cancers in Liangshan state remains unclear and corresponding prevention system had not been established. To provide suitable cervical cancer prevention protocols and facilities, a screen for cervical cancer to develop basic understanding of the current prevalence was urgently required in Liangshan, Sichuan. Methods: A 3-year survey in natural population was conducted in Liangshan, where female residents were recruited from 3 main resident sites and tested for infection of 15 HPV variants using polymerase chain reaction (PCR)-reverse dot hybridization and cytologic abnormality with ThinPrep cytologic tests (TCTs). Personal information on the resident identification cards and contacts were collected for identifying ethnicity and following up in this survey. Those with high-risk HPV infection and/or abnormal TCT results were further diagnosed with colposcopy guided cervical biopsies. Follow-up visits were conducted every 12 months for those with lesion not worse than cervical intraepithelial neoplasia (CIN) grade 1 (CIN1) until progressing to CIN grade 2 (CIN2) or the end of survey. HPV infection rates of Han and Yi Chinese were calculated with age strata and compared. Cancer risks were estimated and compared with data of first and final year and between Han and Yi Chinese. Results: There were 4,723 valid participants including 3,813 Han Chinese, 786 Yi Chinese and 124 of other ethnic minorities involved in this study. At the beginning of the survey, 515 participants (10.90%) were tested positive for HPV, 298 participants (6.31%) were found abnormal in TCTs and throughout the survey 63 cases with severe cervical lesions (CIN2 or worse) were reported. Of those with severe lesions, most patients were infected by HPV 52, 16 and 58. The HPV infection rates in the first screen were 10.46% for Han Chinese but 13.10% for Yi Chinese which was significantly higher with a P value of 0.03, resulting severe cervical lesion rates of 1.29% and 1.68% respectively. Conclusions: Significantly higher HPV infection rate and severe lesion rate were reported on Yi Chinese, suggesting more attention should be paid to Yi Chinese in developing cervical cancer prevention schemes. Compared to other HPV variants, HPV16 was mostly found associated with severe cervical lesions while HPV52 was the most prevalent. Fortunately, both variants are covered by HPV vaccines indicating vaccination should be considerably effective in Liangshan state.