Human Papilloma Virus in the Etiology of Head and Neck Cancers in Sudan; ‘ An immunohistochemical and molecular study

Abstract

Abstract Background Head and neck cancers (HN) are considered as ‘the sixth most common cause of death worldwide. In Sudan, HNCs represents 13.5% of all cancers. Tobacco_ use and alcohol consumption are the main risk factors for head and neck cancers. Other risk factor includes the viral infection, paiticularly with Human papilloma virus HPV which is responsible of about 20% of oral cancers, 70% of oropharyngeal cancers and 8% of other head and neck cancers. Aim _ The aim of this study was to investigate human papilloma virus in the etiology of head and neck cancers in Sudan, using immunohistochemistry and molecular methods. Material and methods This is a retrospective descriptive study conducted at Khartoum State during the period from January 2010 to December 2012. Two hundred tissue blocks were retrieved from different histopathology laboratories in Khartoum State. Of the 200 formalin fixed paraffm wax processed tissue blocks, 150 were obtained from patients diagnosed with head and neck cancers and 50 samples were obtained fiom patients diagnosed with benign head and neck lesions. Infection with HPV was initially determined using pl61NI“A as a biomarker immunohistochemistry (IHC) methods, and then genotyping was subsequently assessed applying PCR. Tumor DNA was amplified using polymerase chain reaction (PCR) with high risk human papilloma virus consensus and multiplex primers. The expression of epidermal growth factor receptors (EGFR), P53 and CD5 as tumor markers were assessed in HNCs as well as in benign head and neck tumors using irnmunohistochemistry. The mean count of nucleolar organizer regions (NORs) was determined in head and neck cancers and benign head and neck tumors using silver impregnation method. Results Analysis of demographical characteristics showed that the age of the study population was ranging fi'om 9 to 85 years with a mean age of 51 years. The male female ratio was 1.67:1. Approximately, 96% of HNCs were squamous cell carcinomas and 4% were adenocarcinomas. HPV was detected in 31/200 (15.5%) cases of head and neck tumors (28 (14%) cases malignant and 3 (1.5%) cases benign). Statistically, -HPV was significantly associated with head and neck cancers, the p-value=0.032. HPV was detected in the age group 31-40 years. According to relation between HPV and lesion sites, the most affected sites were oral cavity, esophagus and larynx. The genotyping of HPV with PCR revealed the presence of high risk human papilloma virus HRHPV in six cases of head and neck cancers, including 3/6(50%) cases in the oral cavity and 3/6(50%) cases in the larynx. The detected I-IRHPV were type 16, 18 and 33. The expression of epidermal growth factor receptors EGFR was found in 84% of HNCS and 12% of benign head and neck tumors. Statistically there was significant association between EGFR and head and neck cancers, the P-value= 0.000. In regard to the relation between P53 and head and tumors, we found that P53 was expressed in 19.3% of HNCs and 4% of benign head and neck tumors. Statistically, P53 was significantly associated with HNCs, the P-value=0.009. CD5 expression was only found in 14.7% of HNCs and 8% of benign head and neck tumors. Statistically no significant association between CD5 and HNCs. P-value=0.225. The association between nucleolar organizer region mean count (NORs) and head and neck cancers was statistically significant. P-value=0.000, but no significant association between (NORs) mean count and P16 expression in head and neck cancers. P-value=0.190. Conclusion In conclusion, the findings of this study provide strong association between HPV and head and neck cancers, particularly oral, esophagus and laryngeal cancers amongst Sudanese patients. On the other hand, when the confirmation of the diaghosis of head and neck squamous cell carcinoma is required, the application of EGFR immunohistochemical method should be considered. The -use of AgNORs mean count analysis in head and neck tumors is recommended in Sudan, particularly for low-income patients.