© 2019 Discovery Publication. All Rights Reserved. www.discoveryjournals.org OPEN ACCESS ARTICLE Page42 RESEARCH Prevalence of human papillomavirus in oral and laryngeal squamous cell carcinoma: A comparative study by polymerase chain reaction Sadiq Musa Ahmed 1 , Sami Khalef Jabar 2 Squamous cell carcinoma (SCC) is the most common malignant histological type in Oral cavity and Larynx. Human papillomavirus (HPV) is one of the most common causes of sexually transmitted disease in both men and women worldwide. It is associated with a variety of clinical conditions that range from innocuous lesions to cancer. Human papillomavirus (HPV) has been confirmed the primary etiological factor that transforms cervical epithelia into cancer. The presence of HPV in oral and laryngeal cancers suggests that HPV may play a similar role in transforming the oral epithelia. The study aimed to determine the prevalence of human papillomavirus infection in oral and laryngeal squamous cell carcinoma in Iraqi patients with high risk typing 16,18. Total of 80 cases oral and laryngeal squamous cell carcinoma are enrolled in this study, forty cases for each. The study sample analyzed by PCR to determine the HPV positive and negative cases using consensus probe. Genotyping of HPV was performed using a specific probe for high oncogenic-risk HPV genotypes16, 18. Demographic data of the study sample showed that males were more than females (62.5 %, 37.5%) respectively. No statistical difference in age groups was found among the study groups, while there was a significant difference in grading among study them (P-value = 0.04). Polymerase chain reaction revealed positive HPV in 12 cases (15%). High- risk HPV16 was detected in 9 cases (2.5% laryngeal SCC and 20% were oral SCC). No significant relation was found between HPV in respect to the histopathological grade, gender and age group in the total sample. The high-risk HPV16 detection in 20% of oral squamous cell carcinoma cases it might play a role in transforming the oral epithelia. There was no significant association between HPV-16 DNA and the demographic data of OSCC. INTRODUCTION Cancer is the common term for numerous distinct diseases characterized by the uncontrolled growth of abnormal cells as a result of mutations in specific genes (1). Specific infections represent other major cancer risk factors with an estimated 2.1 million (16.4%) of the 12.7 million new cases in 2008 attributable to infection. The most important infectious agents are Helicobacter pylori, Hepatitis B and C viruses and Human papillomaviruses (2). Furthermore, genetic changes have been linked to environmental factors such as physical carcinogens - ultraviolet (UV) and ionizing radiation chemical carcinogens: asbestos and tobacco smoke, biological carcinogens - viral infections (Hepatitis B or Human Papilloma Virus HPV), bacteria (Helicobacter pylori) (2). Human papillomavirus (HPV) is a non- enveloped double-stranded, circular DNA virus that has been implicated in a variety of anogenital and aero- digestive diseases, ranging from common warts to laryngeal papilloma to cervical cancer (3). The first isolation of these virus particles was performed in 1933 in rabbit papillomatosis (2). These viruses infect cells in the basal layer of squamous epithelium and the different types have been traditionally separated based on tropism for cutaneous and mucosal sites, as well as high, intermediate, and low risk, depending on their association with malignancy (4). In 1950, the carcinogenic potential of the human papillomavirus (HPV) was discovered in patients with epidermodysplasia verruciformis (5). Although the first suggestion that HPV may play a role in the development of oral cancer was proposed only many years later a number of molecular and epidemiological studies have provided a strong correlation between high-risk HPV infection of the oral mucosa (specifically the oropharyngeal region) and the development of HNSCC (6). The International Agency for Research on Cancer (IARC) in 2003 determined that the infection of HPV is highly likely to play an etiologic role in HNSCC (7). Polymerase chain reaction is a method of amplifying target sequences from a DNA specimen, thus providing a higher degree of sensitivity and specificity than traditional hybridization methodologies. Polymerase chain reaction requires relatively small amounts of DNA (25–500 ng); consequently, the technique can be applied to DNA extracted from formalin-fixed paraffin-embedded tumor tissues (8). MATERIALS AND METHODS The study sample included 80 Formalin-fixed, paraffin embedded (FFPE) tissue blocks which were diagnosed as oral and laryngeal squamous cell carcinoma (40 cases for each) obtained from archival RESEARCH 23(95), January - February, 2019 Medical Science ISSN 2321–7359 EISSN 2321–7367 1 Lecturer, Surgeon, Department of Surgery, Faculty of Medicine, University of Misan, Misan, Iraq; 2 Assistant Professor, Department of Anatomy, Faculty of Medicine, University of Misan, Misan, Iraq  Corresponding author: Dr. Sadiq Musa Ahmed, Affiliation: Misan University, Faculty of Medicine, Address: Iraq, Misan, Amarah city, Postal code: 62001, Tel: 009647733962400, E-mail: medicalresearch11@yahoo.com; ORCID ID: https://orcid.org/0000-0003-1998-9667