MECCS

MEXICAN CERVICAL CANCER SCREENING STUDY

Our work in Mexico initially  involved the “The Mexican cervical cancer screening study” (MECCS) which took place between September 2002 and October 2004 in the State of Michoácan. Primary screening was by self-sampling for high-risk human papillomavirus (HR-HPV). 8,621 women (ages 30-50) were screened and 14.3% were positive for HR-HPV. Secondary screen was unaided visual inspection (VIA). The objectives of this study were to estimate the percent reduction in colposcopy rate, and determine the risk of invasive cancer in women who were self-sampling positive for high-risk HPV and VIA negative therefore potential candidates for ablation of the transformation zone without biopsy confirmation. As a corollary, this protocol estimated the risk of over-treatment with cryotherapy (one or two HPV positive test results with negative cervical histology), or under-treatment (large pre-cancerous lesions or cancer treated with cryotherapy) in the study population. All patients who were colposcoped were evaluated by our standard biopsy protocol. In this trial, the referral to colposcopy rate with colposcopy based on a VIA secondary triage plan for lesions diagnosed as unsuitable for cryotherapy (4 true positives and 5 false positives) was 9/1229 (0.73%). It was noted that if one time HR-HPV positive/ VIA positive, and dual HR-HPV positivity are the criteria for cryotherapy, there would be 129 women who had normal biopsies and 67 women with CIN I who would be treated 196/295 (66.4%). If cryotherapy was used to ablate the transformation zone in women who were one time HR-HPV positive and VIA positive or twice self-test HR-HPV positive 3.4% (11/326) with undetected large CIN II-III, endocervical disease, adenocarcinoma-in-situ, or invasive cancer would likely be inadequately treated. We concluded from MECCS that the study algorithm likely would decrease the rate of colposcopy from 14.3% to <1.0%, but has drawbacks of the need to recall the 14.3% of the population that were self-test HR-HPV positive, a delay in diagnosis of invasive cancer, and possible ineffective ablation of the transformation zone in 4.1% of women. Based on this study, we were encouraged to explore a more sensitive and specific “real time” diagnostic modality that could allow a “see and treat” protocol. In addition it could eliminate the need for patient recall and therefore the problem of lost to follow-up which is so problematic in underserved populations in all parts of the world including the United States. MECCS II was then designed to study  the new POI/NIH self-sampler and some new HPV technology.

View the MECCS photo gallery.