Incidence of Human Papillomavirus Infection in Esophageal Squamous Cell Carcinoma Among Young Individuals in Kenya - a Retrospective Look

Abstract

Background: Esophageal cancer is the fourth most common cancer and the third leading cause of cancer mortality in Kenya. Human papillomavirus (HPV) types 16 and 18 are known to cause majority of squamous cell carcinomas of the cervix, vulva, anus, and oropharynx. East Africa has a high incidence of squamous cell carcinoma of the esophagus similar to the Asian esophageal belt without clear etiology. There is limited information on the association of HPV and esophageal carcinoma in Kenya and the topic remains controversial. Broad objective: To determine the frequency of HPV infection in ESCC in young individuals through p16 staining. Methods: This was a retrospective, cross-sectional study conducted on patients with biopsy proven squamous cell carcinoma of the esophagus at Kenyatta National Hospital. After IRB approval, we reviewed the charts of a young population, 20-50 years old, who received therapy for esophagus cancer at the cancer treatment center from 2016 to 2020. Patients with nonsquamous histology, incomplete medical records, or those without available tissue specimen were omitted. P16 immunohistochemistry staining was performed on slides created from paraffin embedded tissue blocks obtained from tissue repository. Statistical analysis was done in SPSS version 21.0. Chi square and T-test were used to assess statistical significance of distribution by tumor site and other factors in demographics. Incidence presented as percentage and baseline characteristics and distribution of tumor by location and geography presented using tables, pie charts and bar graphs. Results: A total of 51 participants met inclusion with available specimen for review. The majority of patients were from Eastern and Central Provinces of Kenya with the majority of patients not having a history of tobacco use (60.8%) or alcohol consumption (66.7%). The median age was 46 years (range, 20-50) and male to female ratio of 1.7:1. Most patients had tumors located in the middle thoracic esophagus on endoscopy (37.3%). All patients had T3 (46.5%) or T4(53.5%) disease. The node positive rate was 55.8%. 9.8% of the participants stained positive for P16 on immunohistochemistry. There was no statistical difference in patient and tumor characteristics for patients with p16 positive vs. negative tumors. Conclusion: While the availability of biospecimens was limited, we observed 9.8% incidence of positive P16 esophagus squamous cell carcinoma from a young patient population in Kenya. Our report is the first that shows positive staining for p16 amongst esophagus cancer patients in Kenya