A pilot study of HPV DNA and cytology testing in 50,159 women in the routine Mexican Social Security Program.
BACKGROUND
We present a large feasibility evaluation of high-risk HPV (HR-HPV) DNA testing and cervical cytology as a primary screening strategy for cervical cancer precursor lesions in Mexican women, as part of a routine cancer control program (CCP).


METHODS
A community-based study was carried out in 50,159 women aged 20-70 years who visited the CCP in 12 federal entities located in Northern, Central, and Southern Mexico, including a total of 48 primary health care units of the Instituto Mexicano del Seguro Social (IMSS). Cervical specimens for cytology and HR-HPV tests were collected at baseline. Women with cytological abnormalities (ASCUS or greater) were referred to colposcopy for further evaluation and treatment if necessary. A subset of HR-HPV-positive women without cervical lesions, in Morelos state, were tested again for HR-HPV DNA within a year, and repeat-positive women were referred to colposcopy.


RESULTS
HR-HPV prevalence among all women was 8.6% (95% CI: 8.3-8.9). Prevalence by age group was 12.2% (95% CI: 11.0-13.3) before 30 years of age and decreased to 7.4% (95% CI: 6.7-8.0) between 46 and 50 years of age. A second minor prevalence peak (8.1%; 95% CI: 7.2-9.0) was observed in women more than 55 years of age. Overall prevalence of cytological abnormalities was relatively low (2.2%; 95% CI: 2.0-2.3) with the highest frequency of abnormal cytology (ASCUS or greater) in the 41-45 year age group (2.5%: 95% CI 2.1-2.7). No correlation between cervical abnormalities and HR-HPV prevalence, by region, was observed. A total of 370 (0.7%) women had an abnormal cytology as well as a positive HR-HPV result; 736 (1.5%) had an abnormal cytology and a negative HR-HPV test; 3,941 (7.9%) women had a positive HR-HPV test and a normal cytology; and 45,112 (89.9%) women were negative in both tests. The first two groups were immediately referred to colposcopy, 72.7% of the women from the cytology-positive and HR-HPV-positive group and 58.0% from the cytology-positive and HR-HPV-negative group successfully completing evaluation. Among the 269 cytology-positive and HR-HPV-positive women, 53 (19.7%) CIN2/3+ cases were detected, whereas among the 427 cytology-positive and HR-HPV-negative participants, only 13 (3.0%) CIN2/3+ cases were documented. In Morelos state, a sample of 287 women with a negative cytology smear and a positive HR-HPV test at baseline were re-screened after ~12 months, by means of cytology and HR-HPV testing. Among these women, 106 (36.9%) were again HR-HPV positive and were referred to colposcopy. Of whom, 76 (71.7%) were successfully evaluated; among these women, 9 CIN2/3+ (11.8%) were documented. Sensitivity of cervical cytology for detecting histologically confirmed CIN2/3+ cases was only 40.0% (95% CI 38.5-41.4) compared to 93.3% (95% CI 92.5-94.0) for HPV DNA testing considering the additional cases detected among women with persistent HPV infection. The specificity of cytology was 97.0 vs. 89.2% for the HPV DNA test.


CONCLUSIONS
Population-based programs using HR-HPV testing can improve cervical cancer prevention and control in Mexican and other populations where cytological screening is inadequate for detecting precursors of cervical cancer.
Lazcano-Ponce
Eduardo
E
Center for Population Health Research, National Institute of Public Health, Cuernavaca, Morelos, Mexico. elazcano@insp.mx
Lörincz
Attila T
AT
Salmerón
Jorge
J
Fernández
Irma
I
Cruz
Aurelio
A
Hernández
Pilar
P
Mejia
Ivonne
I
Hernández-Avila
Mauricio
M
D000328:Adult; D000368:Aged; D003127:Colposcopy; D003581:Cytodiagnosis; D004279:DNA, Viral / Q000302:isolation & purification*; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods; D008800:Mexico; D008875:Middle Aged; D027383:Papillomaviridae / Q000235:genetics; D030361:Papillomavirus Infections / Q000175:diagnosis*; D010865:Pilot Projects; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012943:Social Security; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000821:virology*; D014626:Vaginal Smears; D055815:Young Adult; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis / Q000821:virology
D004279:DNA, Viral