Assessment of the Validity and Reproducibility of the Pap Smear in Mexico: Necessity of a Paradigm Shift.

BACKGROUND AND AIMS: An assessment was performed of the quality of Pap readings in 19 cytology laboratories (CLs) in Mexico from the Cervical Cancer Screening Program. METHODS: Nine CLs were affiliated with the Health Ministry (SSA), and ten were affiliated with the Mexican Social Security Institute (IMSS). Two sets of 200 cervical cytology specimens were prepared, one set for each institution. Fourteen percent of the specimens were positive and six were inappropriate for diagnosis (3%). All cervical cytology specimens were processed in the cytopathology laboratory at the General Hospital of Mexico, and histopathology was available for each positive case. RESULTS: Thirty percent of the SSA reading centers had a sensitivity of at least 80%; however, not one of the ten IMSS laboratories evaluated reached this figure. Some reading centers had a sensitivity <65%, meaning that nearly half of the specimens with a cytology consistent with cervical neoplasm were not identified. DISCUSSION: Given these results, it is a priority to effect a paradigm shift combining various screening tests to improve adherence to standards and enhanced cost-effectiveness of the early detection of cervicouterine cancer (CC) in Mexico.

Potential impact of a 9-valent HPV vaccine in HPV-related cervical disease in 4 emerging countries (Brazil, Mexico, India and China).

BACKGROUND: We estimated the potential impact of an investigational 9-valent human papillomavirus (HPV) vaccine (HPVs 6/11/16/18/31/33/45/52/58) in HPV-related cervical disease in Brazil, Mexico, India and China, to help to formulate recommendations on cervical cancer prevention and control. METHODS: Estimations for invasive cervical cancer (ICC) were based on an international study including 1356 HPV-positive cases for the four countries altogether, and estimations for precancerous cervical lesions were extracted from a published meta-analysis including 6 025 HPV-positive women from the four mentioned countries. Globocan 2012 and 2012 World Population Prospects were used to estimate current and future projections of new ICC cases. RESULTS: Combined proportions of the 9 HPV types in ICC were 88.6% (95%CI: 85.2-91.3) in Brazil, 85.7% (82.3-88.8) in Mexico, 92.2% (87.9-95.3) in India and 97.3% (93.9-99.1) in China. The additional HPV 31/33/45/52/58 proportions were 18.8% (15.3-22.7) in Brazil, 17.6% (14.2-21.2) in Mexico, 11.3% (7.5-16.1) in India and 11.9% (7.5-17.2) in China. HPV6 and 11 single types were not identified in any of the samples. Proportion of the individual 7 high risk HPV types included in the vaccine varied by cytological and histological grades of HPV-positive precancerous cervical lesions. HPV 16 was the dominant type in all lesions, with contributions in low grade lesions ranging from 16.6%(14.3-19.2) in Mexico to 39.8% (30.0-50.2) in India, and contributions in high grade lesions ranging from 43.8% (36.3-51.4) in Mexico to 64.1% (60.6-67.5) in Brazil. After HPV 16, variations in other majors HPV types were observed by country, with an under representation of HPV 18 and 45 compared to ICC. CONCLUSION: The addition of HPVs 31/33/45/52/58 to HPV types included in current vaccines could increase the ICC preventable fraction in a range of 12 to 19% across the four countries, accounting the 9-types altogether 90% of ICC cases. Assuming the same degree of efficacy of current vaccines, the implementation of the 9-valent HPV vaccine in Brazil, Mexico, India and China would substantially impact on the reduction of the world cervical cancer burden.