Comparasion of Pap test reporting rates in conventional smear and liquid-based cytology

Abstract

Objective To compare the reporting rates in conventional Pap smears (CPS) and liquid-based cytology (LBC), and to show the efficiency of the two methods in the cervical screening. Methods From 2008 to 2015, 100 066 cases of CPS and 997 162 cases of LBC were obtained from more than 900 hospitals and medical centers in Shandong province, and sent to the department of pathology, Jinan Kingmed Diagnostics for Pap staining and cytological diagnosis. The Pap reports and histopathologic follow-up results were retrospectively analyzed. Results The positive results reported with in CPS and LBC were similar in 2008 and 2009, and this might be due to the small sample size of CPS. The total reporting rates of LBC in 2010, 2011, 2012, 2013, 2014 and 2015 were 1.6, 2.66, 2.47, 2.72, 2.52 and 1.63 times higher than those of CPS, respectively (χ2=8.32, 128.02, 131.43, 525.88, 578.59, 209.82, all P<0.01). Comparison among the average ages of different cytologically interpretated lesions demonstrated obvious differences (F=193.28, P<0.001). Post hoc analysis showed that the average age of the patient with high grade squamous intraepithelial lesions (HSIL) was 3.9 years older than that with low-grade squamous intraepithelial lesions (LSIL) (P<0.05), and the average age of the patient suffer cervical cancer was 8.2 years older than that with LSIL (P<0.05), and 4.3 years older than that with HSIL (P<0.05). Except for the cancer cases, the rates of atypical squamous cells of unknown significance (ASC-US), atypical squamous cells that cannot exclude HSIL (ASC-H), LSIL, HSIL, atypical glandular cells (AGC) and the total positive rate of LBC were 2.0, 1.6, 2.9, 2.9, 5.0, 2.2 times higher than those of CPS, respectively (χ2=784.82, 33.01, 447.28, 217.66, 3.79, 26.3, P<0.001). The ASC/SIL ratio of CPS and LBC were 3.16, 2.14, respectively. The distribution of ASC and SIL was significantly different when using the two methods (χ2=60.91, P<0.001). Histopathologic CINⅡ, CINⅢ and invasive cervical carcinoma were diagnosed in 57.22%(103/180)、84.70%(393/464) and 100%(17/17) of the patients with cytologic interpretation of ASC-H, HSIL and carcinoma, respectively. No follow-up histopathologic diagnosis was documented in cytology-abnormal patients with CPS test. Conclusions The present study show that the Pap reporting rates of LBC are much higher than those of CPS. LBC method should be the first choice for cervical cancer screening. Key words: Cervical cancer; Liquid-based cytology; Conventional Pap smears; Screening