Sensitivity and specificity of the Pap smear for glandular lesions of the cervix and endometrium

Abstract

Objective: To investigate the sensitivity and specificity of the Pap smear for detection of adenocarcinoma in situ of the cervix (AIS), endocervical adenocarcinoma (ECAC) and endometrial adenocarcinoma (EAC) as well as the overall specificity of the smear for detection of glandular lesions in general.

Study design: Computer records of the laboratory of the QE II Health Sciences Center, Halifax, were searched for patients who had AIS, ECAC or EAC diagnosed on histology between June 1, 1999, and May 31, 2001 and who had had a Pap smear within the preceding year. Computer records were also searched for patients who had a Pap smear result consisting of suspicious or positive for AIS or adenocarcinoma (AC) with subsequent tissue diagnosis during the same time. The histologic and cytologic findings were correlated.

Results: One hundred percent of patients with AIS, 80% with ECAC and 22% with EAC on histology had positive findings on a Pap smear performed within a year of the histologic diagnosis. One hundred percent of patients with a Pap smear result consisting of suspicious or positive for AIS or AC and follow-up histology had a lesion on histology: 13% AIS, 13% ECAC, 37% EAC, 23% other AC, 10% high grade squamous lesion and 0.3% low grade squamous lesion.

Conclusion: This study confirmed the good overall specificity of the Pap smear for glandular lesions in general. It also confirmed the good sensitivity for glandular lesions of the cervix and the poor sensitivity for glandular lesions of the endometrium. It thus confirmed that the Pap smear is not an effective screening tool for endometrial AC, and that the quest for alternative screening methods should continue.