Pathological Characteristics of Prostate Carcinoma in Archival Tissues at the Africa Inland Church Kijabe Hospital, Kiambu County – Kenya

Abstract

Prostate carcinoma (PCa) is the leading cancer among middle and elderly men worldwide. It accounts for 15% of all cancer cases and 6.6% of all cancer associated-deaths in men. PCa is a leading cause of cancer burden among men in Africa with Kenya reporting an incidence of 16.6/100,000. The exceedingly high burden of PCa is largely due to lack of population-based screening and delayed diagnosis in the background of genetic and environmental predisposing factors. Histopathological features of PCa offer prognostic indicators while immunohistochemical (IHC) staining provide insights into the molecular characteristics of PCa which have both prognostic and predictive value in the management of PCa. The androgen receptor (AR), Human epidermal growth receptor (HER2/neu), and protein p53 genes are among the most important genes regulating PCa pathogenesis. IHC staining patterns of these gene products have been associated with different therapeutic and prognostic outcomes. This cross-sectional study determined the histopathological and AR, HER2 and p53 IHC expression on archival simple prostatectomy specimens (n=210) at AIC Kijabe Hospital, a tertiary faith-based health facility in Kiambu County, Kenya. Patient demographic and gross characteristics of the prostatectomy specimens were obtained from the patient files. The tissue blocks (n=210) were retrieved, sectioned and stained using standard H&E and immunohistochemical staining protocols. The slides were then examined using light microscopy and histopathological and immunohistochemical features recorded. Data analyses showed that the median age of the subjects was 74.0 years (44.0 – 99.0). Ethnic groups were represented as follows; Bantu (68.0%), Nilotes (31.0%) and Cushites (1%). Histopathologically, 97.6% of the PCa were of acinar adenocarcinoma type with the rest being of ductal adenocarcinoma type. Perineural invasion (PNI) was present in 57.6% of the PCa while 25.2% had lymphovascular invasion (LVI). Low grade PCa (Gleason score <8) constituted 56.6 % of the cases while high grade PCa (Gleason score ≥8) constituted 43.4% of the cases. The frequencies of the different ISUP grade groups were as follows; ISUP grade 1 (23.3%), grade 2 (16.2%), grade 3 (17.1%) grade 4 (10.5%) and grade 5 (32.9%). This study showed that 34.8% of the PCa were AR negative, 4.5% had HER2 over-expression while 19.7% of the cases showed p53 protein over-expression. Binary logistic regression analyses revealed that Gleason score ≥8 was associated with higher odds for PNI (OR, 40.407; 95% CI, 11.036-147.949; P<0.0001) and gland involvement of ≥50% (OR, 30.447; 95% CI, 7.220-128.397; P<0.0001), but lower odds for AR expression (OR, 0.109; 95% CI, 0.019-0.621; P=0.013). In addition, PCa pathological grade III was associated with PNI (OR, 37.710; 95% CI, 8.762-162.288; P<0.0001), LVI (OR, 33.531; 95% CI, 13.757-81.729; P<0.0001), and gland involvement of ≥50% (OR, 2.291; 95% CI, 1.040-50.500; P=0.040). Likewise, p53 expression was associated with a lack of PNI (OR, 0.157; 95% CI, 0.032-0.778; P=0.023). Altogether, this is the first PCa study outlining the pathological characteristics of PCa in Kenya. This is the first African study that has used ISUP grade groups for PCa. These findings will influence the diagnosis, treatment and prognosis of PCa and might become the standard of care in the country. Further studies to compare patient characteristics, biochemical test results and pathological findings of PCa are recommended.