Background & objective: At present, the incidence of cervical cancer is still high in less developed areas of China; one of the reasons is that cytology in screening for cervical cancer is not feasible in these areas. The aim of this study was to analyze the sensitivity and specificity of acetic acid smear test as a cervical cancer screening test, and evaluate the value of this method for cervical cancer screening.
Methods: Acetic acid smear test was performed on 1997 previously unscreened women aged 35-45 years in Xiangyuan County, Shanxi Province. All women had cervical cytology, testing for high-risk types of human papillomavirus DNA, colposcopy, an endocervical curettage and at least five cervical biopsies. Biopsies were done at the lesions, or one biopsy at 2, 4, 8, 10 o'clock at the squamocolumnar junction in each normal quadrant.
Results: According to histological diagnosis, 43 women had CIN II, 31 had CIN III, and 12 had invasive carcinoma. In two women only the endocervix was positive. Smear test yielded normal results in 1445 women (72.4%), low-grade squamous intraepithelial lesions (LSILs, CIN I) in 525 (26.3%), high-grade squamous intraepithelial lesions (HSILs, CIN II- III) in 21 (1.1%), and cancer in 6 (0.3%). With abnormal visual inspection defined as LSILs or worse, the sensitivity of acetic acid smear test for HSILs or worse was 70.9% (61 of 86), the specificity was 74.3% (1420 of 1911). The sensitivity was 64.9% for smaller lesions (37 of 57), and 88.9% for larger lesions (24 of 27) (P=0.03). The sensitivity of colposcopy for high-grade SILs or worse was 81.4% (70 of 86), the specificity was 76.5% (1462 of 1911).
Conclusion: This study showed the high specificity and sensitivity of acetic acid smear test as a primary screening test for cervical cancer. Acetic acid smear test and colposcopy have similar specificity profiles for CIN II or more severe lesions. Acetic acid smear test as a primary screening test will be possible and effective with the benefits of low-cost and simple test in low-resource settings.