Negative smears in women developing invasive cervical cancer

Area of Science:

• Gynecologic Pathology
• Cervical Cancer Screening
• Cytopathology

Background:

• Cervical cancer screening relies on cytological examination of cervical smears (Pap tests).
• False-negative results in Pap tests can lead to delayed diagnosis and treatment of cervical cancer.
• Screening errors encompass both interpretation mistakes and inadequate sample collection.

Purpose of the Study:

• To re-examine initially negative cervical smears from women later diagnosed with cervical cancer.
• To estimate the rates of screening error and sampling failure in cervical cytology.
• To assess the impact of different sampling methods on cytological evaluation accuracy.

Main Methods:

• Retrospective review of 56 cervical smears initially classified as Pap I.
• These smears were from women diagnosed with stage I-IV cervical cancer within 4-5 years post-cytology.
• Smears were reclassified according to the Pap system (Pap II-V).

Main Results:

• Upon re-examination, 35 out of 56 (62.5%) smears were reclassified from Pap I to Pap II-V.
• The rate of classification change was higher for population screening (70%) compared to private/hospital samples (approx. 50%).
• Sampling failure was implicated, with 14 negative slides lacking columnar cells, suggesting poor sampling of the squamo-columnar junction.

Conclusions:

• A significant proportion of initially negative cervical smears are associated with screening errors or sampling failures.
• Inefficient sampling, particularly the absence of columnar cells, is a critical factor in missed cervical cancer diagnoses.
• Improved sampling techniques are crucial for enhancing the accuracy of cervical cancer screening programs.