BACKGROUNDVaginal intraepithelial neoplasia (VAIN), as a precursor of vaginal cancer, is a rare disease. Its prevalence has not been well analyzed. This research is to ascertain the risk factors for VAIN in a Chinese population.

METHODSA case-control study was conducted, including 63 VAIN cases and 64 healthy controls. In all subjects Pap smear and HPV tests were performed. A questionnaire survey was distributed, covering information on socio-demographic characteristics, smoking, past history, reproductive and sexual histories. The clinical pathological data were collected from medical records including symptoms, Pap smear results, grade of lesions, and human papillomavirus (HPV) status.

RESULTSPostmenopausal women had a 2.09 times higher risk for VAIN than pre-menopausal women (95%CI: 1.10 - 3.85; P = 0.024). The patients with previous hysterectomy had an increased risk of VAIN (OR = 4.69; P = 0.003). Patients with a history of cervical cancer or CIN were predisposed to VAIN (OR = 78.75; P < 0.0001). The rate of HPV infection in VAIN was significantly higher than in controls, and an increased risk of VAIN was observed in patients with higher viral load (OR = 126.00; P = 0.000). Multivariate analysis showed that HPV infection and a history of CIN or cervical cancer were still found to be significant in patients.

CONCLUSIONHPV infection and a history of CIN or cervical cancer are the main risk factors for the development of VAIN.