Evaluation of the HPV ISH assay in cervical cancer

Abstract

Background: Human papillomavirus (HPV) infection can be detected by in situ hybridization (ISH), in which a punctate signal pattern indicates integrated HPV DNA and a diffuse pattern denotes the presence of episomal viral DNA. This study was conducted to evaluate the usefulness of an HPV ISH assay for invasive cervical cancer. Methods: The HPV ISH assay for high-risk HPV and immunohistochemical staining for p16INK4a, p53, bcl-2, and Ki-67 were performed in a tissue microarray of 279 cervical cancers. Results: High-risk HPV ISH was positive in 194 (69.5%) of the samples. Punctate, diffuse, and mixed signal patterns were observed in 157 (56.3%), one (0.4%), and 36 cases (12.9%), respectively. Positive results in high-risk HPV ISH were associated with p16 and bcl-2 expression (p = 0.01 and p < 0.01, respectively). According to a Cox regression analysis, HPV infection and its surrogate immunohistochemical markers such as p16, bcl-2, and Ki-67 were not independent prognostic factors, but stage and grade were independent prognostic factors. Conclusions: Our results confirm that an HPV ISH assay is reasonably sensitive for HPV infection and that it might be useful to identify integrated HPV DNA in formalin-fixed and paraffin-embedded specimens. Further study encompassing HPV type, E2/E6 ratio, and therapeutic modality is necessary to understand the clinical meaning of HPV status in cervical cancer.