Comprehensive Analysis of Ki67 Proliferative Index in Basal Cell Carcinoma: Correlation with Clinical and Histopathological Subtypes

Abstract

Background: Basal cell carcinoma (BCC) is the most common type of non-melanoma skin cancer in the whole world with about 75 percent of all skin-related cancers. It has a close pathogenesis associated with cumulative exposure to ultraviolet (UV) radiation, and major variation in clinical behaviour based on the histopathological subtype. Ki67, a nuclear proliferation, has already become one of the useful markers in differentiating between biologically aggressive and indolent BCC subtypes, but its systematic evaluation among the population of Iraq is still minimal.

Objective: The study aims to examine the clinical pathology features of BCC among patients who visit hospitals of the Wasit Health Directorate and specifically to explore the Ki67 proliferative index of the histological types and the possible application as a prognostic marker.

Methods: A prospective cross-sectional study was carried out in the period between May 2022 and May 2024 at the hospitals of the Wasit Health Directorate. Eighty BCC cases were recruited histopathologically. Demographic information (age, sex, occupation), the location of the tumor and histopathological subtypes were noted. Hematoxylin and eosin (H&E) tissue sections were used. The immunohistochemical assay of Ki67 was done by investigating with MIB-1 monoclonal antibody clone; Ki67 was considered low (less than 10% nuclear staining) and high (greater than 10% nuclear staining) staining. Fisher exact test was used to measure statistical significance.

Results: BCC was higher among the male population (57.5% vs. 42.5 per cent), although the highest incidence was found in the group of patients of 61 years and above (45 per cent). The risk factor of outdoor occupational UV exposure was very high and was found in 42.5% of male patients and 17.5% of female patients. The most prevalent histopathological subtype was nodular (55%), then there were superficial (22.5%), pigmented (8.75%), basosquamous (7.5%), and infiltrative (6.25%). Nine percent percent of aggressive subtypes (basosquamous and infiltrative combined) had high Ki67 expression, versus 16 of non-aggressive subtypes (nodular, superficial, and pigmented, p = 0.001). Most affected anatomical sites were at the nose (55%) and the medial canthus (25%).

Conclusion: The Ki67 immunohistochemical marker expression has proved to be statistically significant regarding BCC histopathological aggressiveness, making it possible to objectively distinguish between indolent and aggressive subtypes. Ki67 analysis included in standard pathology of BCC can help to improve the generalization of prognosis and adjust treatment choices. Such results also highlight a necessity of special attention to effective public health strategies to deal with UV exposure among the occupationally vulnerable Iraqi population.