[Proportion of adenocarcinoma and the distribution of HPV genotypes in China: a meta-analysis]

Objectives: To examine the proportion and trends of cervical adenocarcinoma in cervical cancer (ICC), mainly including cervical adenocarcinoma (CADC) and squamous cervical cancer (SCC) in China, and to analyze the distribution of human papilloma virus (HPV) in CADC and SCC. Methods: Published studies reporting HPVs distribution in various histological types or relative proportions of CADC in ICC in China were identified manually and searched systematically in Medline, Embase, Cochrane Library databases, CNKI and Wanfang since the databases were established until October 2022. Meta-analysis was performed using Stata 16.0 software. And we applied the random-effects models to estimate the combined effect values due to the high heterogeneity. Results: Twenty-three studies were eligible. The relative prevalence of CADC was 9.0% (95% CI, 7.7%－10.3%). According to the diagnosis time of ICC, the patients were divided into three time periods, which is 1979-2005, 2006-2011, 2012-2022 respectively. The prevalence of CADC by time was: 6.0% in 1979-2005, 8.1% in 2006-2011, and 9.5% in 2012-2022, respectively, with no statistically significant trend in proportions over time (χ²=5.03, P=0.081). Meanwhile, the percentage of CADC also varies by regions, and the highest percentage of CADC was found in the eastern region (11.2%), followed by the western region (7.3%) and the central region (5.9%). The total prevalence of HPV infection in CADC was 72.3%, which was lower than 92.0% in SCC, and the difference was statistically significant (χ²=300.89, P＜0.01). To be specific, the top three HPV types prevalent in CADC were HPV18 (45.0%), HPV16 (22.0%), and HPV52 (7.3%), and those prevalent in the SCC were HPV16 (64.2%), HPV52 (5.6%), HPV18 (5.4%). The results of the Egger's test, and Begg's test showed that there was no publication bias in this study and sensitivity analysis showed that the results of this study were fairly stable. Conclusions: The proportion of CADC in China has increased in a limited way in the past decades, and there are regional differences in the proportion of CADC. The predominant type is HPV18 in CADC and HPV16 in SCC. To eliminate the limitations of the secondary literature, a multicenter study with consistent diagnostic levels and identical HPV genotyping tests is still needed in the future to better characterize the relative proportion of cervical adenocarcinoma and the trend of HPV changes, which will provide a basis for the improvement of HPV vaccine and screening policies.