Risk factors of cervical cancer after a negative cytological diagnosis in Polish cervical cancer screening programme.

Risk factors of cervical cancer (CC) development are well investigated, however, those influencing the risk of a potential false negative cytology preceding diagnosis of an invasive CC are not. We have aimed to explore these factors according to the data from Organised Cervical Cancer Screening Programme (OCCSP) in Poland. A total of 2.36 million of Pap tests sampled in 2010-2012 within OCCSP were merged with the Polish National Cancer Registry to identify CC cases after abnormal cytology and after normal cytology within 3 years of screening. Of 1460 invasive CCs, 1025 were preceded by abnormal and 399 by normal cytology result. Multivariate logistic analysis indicated that the presence of microorganisms in the Pap (OR = 2.18, 95% CI 1.65-2.87), evaluation by smaller (below 9000 slides processed per year) laboratories (OR = 1.60, 95% CI 1.22-2.09) and non-squamous histology of cancer increased the odds for a potential false negative result (OR = 3.39, 95% CI 2.37-4.85 for adenocarcinoma, OR = 1.99, 95% CI 1.11-3.55 for other types of carcinoma), whereas cervical ectropion, other macroscopic changes on the cervix and smoking decrease the odds for a potential false negative Pap test result preceding CC (OR = 0.61, 95% CI 0.45-0.82, OR = 0.41, 95% CI 0.25-0.67, OR = 0.60, 95% CI 0.46-0.78, respectively). Proper triage of women with microscopic signs of microorganisms in the Pap smear should be reconsidered and cytology should be assessed in laboratories processing over 9000 slides annually to decrease the odds for negative Pap test result in 2 years before CC diagnosis. Information on macroscopic changes on the cervix provided to cytomorphologist may reduce the risk of a potential false negative cytology result.