Decreasing cervical cancer mortality in Mexico: effect of Papanicolaou coverage, birthrate, and the importance of diagnostic validity of cytology.

BACKGROUND The reduction in cervical cancer mortality in developed countries has been attributed to well-organized, population-based prevention and control programs that incorporate screening with the Papanicolaou (Pap) smear. In Mexico, there has been a decrease in cervical cancer mortality, but it is unclear what factors have prompted this reduction. METHODS Using data from national indicators, we determined the correlation between cervical cancer mortality rates and Pap coverage, birthrate, and gross national product, using a linear regression model. We determined relative risk of dying of cervical cancer according to place of residence (rural/urban, region) using a Poisson model. We also estimated Pap smear coverage using national survey data and evaluated the validity and reproducibility of Pap smear diagnosis. RESULTS An increase in Pap coverage (beta= -0.069) and a decrease in birthrate (beta=0.054) correlate with decreasing cervical cancer mortality in Mexico. Self-reported Pap smear rates in the last 12 months vary from 27.4% to 48.1%. Women who live in the central (relative risk, 1.04) and especially the southern (relative risk, 1.47) parts of Mexico have a greater relative risk of dying of cervical cancer than those who live in the north. There is a high incidence of false negatives in cervical cytology laboratories in Mexico; the percentage of false negatives varies from 3.33% to 53.13%. CONCLUSIONS The decrease in cervical cancer mortality observed in Mexico is proportional to increasing Pap coverage and decreasing birthrate. Accreditation of cervical cytology laboratories is needed to improve diagnostic precision.