p16INK4a/Ki-67 dual stain cytology for cervical cancer screening in Thika district, Kenya

Caroline Wangari Ngugi, Dietmar Schmidt, Karanja Wanyoro, Hamadi Boga, Peter Wanzala, Anne Muigai, John Mbithi, Magnus von Knebel Doeberitz, Miriam Reuschenbach

The identification of suited early detection tests is one among the multiple requirements to reduce cervical cancer incidence in developing countries. We evaluated p16(INK4a)/Ki-67 dual-stain cytology in a screening population in Thika district, Kenya and compared it to high-risk human papillomavirus (HR-HPV) DNA testing and visual inspection by acetic acid (VIA) and Lugol's iodine (VILI). Valid results for all tests could be obtained in 477 women. 20.9 % (100/477) were tested positive for HR-HPV DNA, 3.1 % (15/477) had positive VIA/VILI and 8.2 % (39/477) positive p16(INK4a)/Ki-67 cytology. Of 22 women that showed up for colposcopy and biopsy, 6 women were diagnosed with CIN3 and two with CIN2. All women with CIN2/3 were negative in VIA/VILI screening and positive by HR-HPV DNA testing. But HPV was also positive in 91.7 % (11/12) of women with normal histology. p16(INK4a)/Ki-67 cytology was positive in all 6 women with CIN3, in one of the two CIN2 and in only 8.3 % (1/12) of women with normal histology. p16(INK4a)/Ki-67 cytology is an interesting test for further studies in developing countries, since our findings point to a lower fraction of false positive test results using p16(INK4a)/Ki-67 cytology compared to HPV DNA testing in a Kenyan screening population. VIA/VILI missed all histology-proven CIN2/3.