P16 as a molecular biomarker of cervical adenocarcinoma John O. Schorge, MD, a Jayanthi S. Lea, MD, a Keren J. Elias, a Ramababu Rajanbabu, a Robert L. Coleman, MD, a David S. Miller, MD, a Raheela Ashfaq, MD b Laboratory of Gynecologic Oncology, Department of Obstetrics and Gynecology, a and the Department of Pathology, b University of Texas Southwestern Medical Center, Dallas, Tex Received for publication May 7, 2003; revised July 13, 2003; accepted September 18, 2003 – Objective: Cervical adenocarcinomas are increasing in incidence each year. The aim of this study was to identify a molecular biomarker to improve early detection. Study design: Fifty-five in situ and invasive cervical adenocarcinomas were compared with 5 nor- mal endocervical controls by immunohistochemical analysis of p16, p21, p27, cyclin D1, cyclin E, p53, and Ki-67. Expression was scored from 0 to 8 by using an automated imaging system. West- ern blotting and polymerase chain reaction-based human papillomavirus (HPV) testing were performed on 16 of the invasive cases having fresh-frozen tissue. Results: P16 exhibited a higher mean expression score for in situ (7.4; P ! .0001) and invasive cervical adenocarcinoma (6.6; P ! .0001) versus controls (2.0). A cutoff p16 expression score of 5 had a sensitivity of 94.5% and a specificity of 100%. Western blotting confirmed p16 protein expression. Fourteen (88%) of 16 invasive cervical adenocarcinomas were HPV-positive. Conclusion: P16 is a putative molecular biomarker of cervical adenocarcinoma. Overexpression appears to primarily reflect HPV-induced cell cycle dysregulation. Ó 2004 Elsevier Inc. All rights reserved. KEY WORDS P16 Biomarker Cervical adenocarcinoma Adenocarcinoma in situ – Cervical adenocarcinoma is increasing in incidence worldwide, particularly among younger women. 1 In the United States, adenocarcinomas currently account for 24% of all cervical cancers diagnosed each year. The proportion has increased 107% relative to all cervical cancer and 95% relative to squamous cell carcinoma over the past few decades. 2 Most cervical adenocarcinomas invade from a preexisting focus of in situ disease after a latency period of several years. 3 Although there should be ample time for screening and potential inter- vention before invasion, precursor lesions are notori- ously difficult to detect with routine Papanicolaou smears. Liquid-based cervical cytology does offer some improvement in the detection rate of glandular abnor- malities. 4,5 Molecular biomarkers are also potentially useful in distinguishing cervical adenocarcinoma from benign mimics. 6 Immunohistochemical staining of MIB1, bcl-2, p16, carcinoembryonic antigen, p53, and other putative diagnostic markers has shown potential in dis- criminating between benign and malignant endocervical glandular lesions. 7,8 Proteins that regulate the cell cycle This study was supported by the 2002 Berlex Scholar Award in Basic Science Research awarded to J.O.S. Reprint requests: John O. Schorge, MD, Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, J7.124, Dallas, TX 75390-9032. E-mail: john.schorge@utsouthwestern.edu American Journal of Obstetrics and Gynecology (2004) 190, 668e73 www.elsevier.com/locate/ajog 0002-9378/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.ajog.2003.09.038