Abstract
Objective To provide a scientific basis for the prevention and treatment of cervical intraepithelial neoplasia grade 1 (CIN1). This study evaluated the impact of human papillomavirus (HPV) infection on the natural history of CIN1. Methods Electronic databases of Cochrane Library, EMBASE, PubMed, CNKI, CBM, and Wanfang were searched in April 2016. The eligibility criteria were documented by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We used the Newcastle-Ottawa scale (NOS) to assess study quality. Results Thirty-eight studies out of 3,246 identified papers were eligible for inclusion. The risk of CIN1 progression (relative risk [RR]: 3.04; 95% confidence interval [CI]: 2.41–3.83; P < 0.00001) and persistence (RR: 1.48; 95% CI: 1.17–1.87; P = 0.001) was higher in the HPV-positive group than HPV-negative group. Specifically, the risk of CIN1 progression (RR: 13.91; 95% CI: 3.46–55.90; P = 0.000) was higher among persistent high-risk HPV-positive patients and the ratio of CIN1 regression (RR: 0.65; 95% CI: 0.59–0.71; P < 0.00001) was lower in the HPV-positive group than HPV-negative group. Conclusion HPV infection resulted in an increased risk of CIN1 progression and decreased disease reversibility. Persistent high-risk HPV infection resulted in a further increased risk of CIN1 progression.
Highlights
Cervical intraepithelial neoplasia grade 1 (CIN1) is a precancerous lesion closely related to cervical cancer and characterized by a shorter and less observable clinical course
We systematically reviewed published studies according to the following inclusion criteria: studies examining the impact of Human papillomavirus (HPV) infection on the natural history of CIN1 disease; studies including at least HPV-negative and HPV-positive; results at the start and end of follow-up including cervical histology or cytology, a diagnosis consistent with the CIN classification system or atypical hyperplasia and the carcinoma in situ (CIS) classification system; patients diagnosed with CIN1 who did not undergo interventions including cryosurgery, electrocoagulation therapy, laser therapy, microwave therapy, cold knife conization, loop electrosurgical excision procedure, and trachelectomy; follow-up observation for at least 6 months; complete information so that each document contained sufficient information to calculate statistical indicators of relative risk (RR) or 95% confidence intervals (CIs)
Twenty-five studies examined persistent CIN1 and 36 articles evaluated the progression from CIN1 to highgrade cervical intraepithelial neoplasia and cervical cancer (CIN2+)
Summary
Cervical intraepithelial neoplasia grade 1 (CIN1) is a precancerous lesion closely related to cervical cancer and characterized by a shorter and less observable clinical course. 90% of CIN cases and over 99% of cervical cancer cases occur in HPV-positive patients [2]; HPV testing has become a major component of cervical disease screening, diagnosis, and follow-up. The association between CIN1 and HPV remains controversial. The results of several studies suggest that CIN1 is mainly caused by low-risk HPV infection [3,4,5]. There is evidence that high-risk HPV is strongly associated with CIN1 [6, 7]. Differences in the risk of HPV infection and CIN1 disease outcome [8, 9] may be due to regional differences in populations. There are scarce independent systematic reviews on the effects of HPV infection and CIN1. This study evaluated the impact of HPV infection on the natural history of CIN1 by conducting a literature review in order to provide a scientific basis for the prevention and treatment of CIN1
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