[Indications for p16/Ki-67 in cervical cytology]

Abstract

Background: The p16/Ki-67 immunocytochemistry has been used for more than five years in cervical cytology to detect transforming HPV infections.

Material and methods: Based on findings in the study presented here and data in the literature, practically relevant indications for this test are to be determined. The clinical course of 1109 patients with varying primary cytology results and simultaneous immunocytochemistry is analyzed. Short-term observations considering currently present lesions and long-term follow-up evaluation aimed at the prognostic evaluation are studied separately and compared with the literature.

Results: The p16/Ki-67 immunocytochemistry effectiveness is described by the relative risk (RR) for the positive endpoint CIN2+. For short-term observations (n = 409) a RR of 3.79 (CI 95% 2.15 to 6.67) and for long-term follow-up (n = 700) after an average 34.7 months a RR of 8.72 (CI 95% 5.77 to 13.17) was found. The highest RR of 6.32 (CI 95% 3.71 to 10.76) was determined for the group IIID1/LSIL, followed by 3.98 (95% CI 1.45 to 10.91) for the group III-p (ASC-H).

Discussion: Regardless of the study designs and significant differences of the resulting statistics in the literature, there is consensus concerning the significantly higher specificity and positive prediction of the p16/Ki-67 immunocytochemistry compared to cytology or HPV DNA test results. Therefore, p16/Ki-67 immunocytochemistry is useful in cases of persistent group IIID1/LSIL and equivocal cytological findings (group III-p/ASC-H). Especially in the former group, the frequency of colposcopic examinations can be reduced. In this respect, adding p16/Ki-67 immunochemistry likely improves patient management. However, an indication for treatment solely based upon a positive immunocytochemical finding is unjustified.

Keywords: CIN; Cervical cytology; Indications; Ki-67; P16.