NEW YORK (Reuters Health) Oct 21 - Dual-stained cytology with the biomarker combination p16/Ki-67 improves the detection of cervical cancer precursors, especially in younger women, according to results from the PALMS study conducted in Europe.
"There is growing data and evidence that specifically combining p16/Ki-67 dual-stain cytology with HPV testing may provide an attractive option to efficiently screen for cervical cancer precursor lesions," Dr. Ruediger Ridder from Ventana Medical Systems, Inc., Tucson, Arizona told Reuters Health by email.
"The combination of both tests may rule out disease (negative prediction) and identify women with existing cancer precursors (positive prediction) very efficiently," Dr. Ridder said.
Overexpression of p16 reflects transforming HPV infections and precancerous cervical lesions, and presence of Ki-67 in the same cell is a hallmark of cell-cycle deregulation. Normal cells do not simultaneously express p16 and Ki-67.
Dr. Ridder and colleagues compared the p16/Ki-67 dual-stained cytology approach with Pap cytology testing in a routine European cervical cancer screening population of 6,798 women ages 18 to 29 and with HPV testing in 20,450 women age 30 or older.
The overall prevalence of positive dual-stained cytology was 5.4%, similar to the prevalence of atypical squamous cells of undetermined significance (5.2%) and half the prevalence of HPV (10.7%), according to a report online October 4th in the Journal of the National Cancer Institute.
Based on 181 cases of biopsy-confirmed cervical intraepithelial neoplasia of grade 2 or higher (CIN2+), the sensitivity of dual-stained cytology was 86.7%, significantly higher than that of Pap cytology (68.5%). Specificity was similar for dual-stained cytology (95.2%) and Pap cytology (95.4%).
Dual-stained cytology was significantly more sensitive than Pap cytology in both age groups (18-29 years and 30 years and over), but HPV testing was significantly more sensitive (93.3%) than dual-stained cytology (84.7%) in the older group, although it was significantly less specific (93.0% versus 96.2%, respectively).
Because women under 30 with negative results (except for HPV) were not referred to colposcopy, longitudinal data will be needed to assess the risk of developing high-grade CIN after a negative dual-stained cytology result.
"In women of increasing age, dual-stain cytology can be used to select women with positive HPV test screening results who may benefit most from immediate referral to colposcopy for further diagnostic follow-up," Dr. Ridder said. "In younger women, dual-stain cytology can be used as a primary screening test, and HPV testing may be used for further triaging positive dual-stain cytology test results."
"With dual-stain cytology, the medical community will have a new option that may further improve the way we screen women to prevent cervical cancer," Dr. Ridder concluded. "The best combination of tests needs to be evaluated at the national level and may vary, based on existing screening programs and algorithms in individual countries."
"Clinical implementation of p16/Ki-67 testing would require resolution of several issues, including the feasibility of performing the stain routinely, the need for training and certification of cytologists, and clinical validation," write Dr. Mahboobeh Safaeian and Dr. Mark E. Sherman from National Cancer Institute, Bethesda, Maryland in an editorial.
"As more vaccinated women undergo screening," they add, "the performance of testing may change, and re-evaluation of these approaches may be required. Nonetheless, developing simple effective screening algorithms will be important."
Roche mtm laboratories funded the study, employed two of the 17 authors, and provided funding of various sorts to most of the remaining authors and/or their institutions.
SOURCE: http://bit.ly/19Xhmii
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