Expression of ARID1A in Penile Squamous Cell Carcinoma and its association with age, histological subtypes and grades in the Pathology Department, Makerere University.

Abstract

Background: About ninety-five percent (95%) of penile carcer arise in the squamous epithelium, giving rise to squamous cell carcinoma. Worldwide, the incidence and global health burden of penile cancer is in the range of 0.1-7.9 per 100,000 males where it accounts for approximately 1% of male malignancies. Uganda has one of the highest worldwide incidence rates of about 4.4 per 100,000; nationwide it is also the second most commonly diagnosed male genital cancer after prostate cancer in Kyadondo county (1). Age is an independent risk factor for penile SCC with diagnosis commonly seen in males between the ages of 50 to 70 years (2); (3). Histological subtype and grade are prognostic indicators of penile SCC. Adenine-thymine rich interactive domain 1A(ARID1A) protein is expressed in penile cancer and associated with histological grade (4). This study assessed the immunohistochemical expression of ARID1A protein in penile squamous cell carcinoma (SCC) and its association with clinicopathologic features of penile SCC. Methods and Results: This was a retrospective cross-sectional study using archived paraffin embedded tissue blocks of patients histologically diagnosed with Penile SCC from January 2010 to December 2019. A total of eighty-six (86) confirmed cases of penile squamous cell carcinoma were analyzed with H and E and Immunohistochemistry. The mean age was 58.5 years with 50% of cases between the ages of 51 to 70 years and 72.1% of cases above the age of 50 years. Distribution of histological subtypes showed Usual SCC to be 75/86;(87.2%); Verrucous 9/86;(10.5%); Basaloid 1/86;(1.2%) and Sarcomatoid 1/86;(1.2%). Histological grades were distributed as follows: well differentiated 52/86;(60.5%); moderately differentiated 21/86;(24.4%) and poorly differentiated 13/86;(15.1%). Adenine-thymine rich interactive domain 1A was expressed in 77/86 cases accounting for 90% of all cases. Chi square test showed no association between ARID1A expression and age, histological subtype and histological grade; p=0.701, p=0.371 and p=0.820 respectively. The Kruskal-Wallis and Cuzick tests also showed no associations and trend amongst ordered groups, respectively. Conclusion: 90% of cases expressed ARID1A, with no association with age, histological grade or subtype. This is unlike a 100% expression and association with histological grade seen in a previous study. With such varying results and taking into consideration the association between histologic grade and prognosis, future studies on the subject matter is warranted with focus on the predictive value of ARID1A expression in penile SCC.