Prognostic utility of epidermal growth factor receptor (EGFR) expression in prostatic acinar adenocarcinoma

ABSTRACT

Background: Epidermal growth factor receptor (EGFR) is potential prognostic biomarker expressed in many human cancers. Prognostic significance of EGFR immunohistochemical expression has not been established in prostatic acinar adenocarcinoma, therefore we aimed to evaluate the frequency of expression of EGFR in prostatic adenocarcinoma and its association with other prognostic parameters. Methods: The study included 123 cases of biopsy proven prostatic acinar adenocarcinoma treated at Liaquat National hospital, Karachi from January 2013 till December 2017. Paraffin blocks of all cases were retrieved; sections were cut and stained with haematoxylin and eosin. Pathologic characteristics including tumor quantification, WHO grade group, gleason score, perineural and lymphovascular invasion were evaluated. EGFR immunohistochemistry (IHC) was performed on all tissue blocks. Results: Mean age of the patients included in the study was 69.05±8.68years. High gleason scores i.e. 8 & 9 were noted in 22% (27 cases) and 22.8% (28 cases) respectively. Similarly, 22.8% (28 cases) showed WHO grade group 5. 52.8% (65 cases) had > 50% tissue involvement by carcinoma and perineural invasion was seen in 37.4% (46 cases). Positive EGFR expression was noted in 18.7% (23 cases), while 81.3% (100 cases) showed negative EGFR expression. Significant association of EGFR expression was noted with gleason score (p-value = < 0.001), WHO grade (p = < 0.001), tumor quantification (p =0.007) and perineural invasion (p = < 0.001). Moreover, significant association of EGFR expression was also seen with disease recurrence and Her2neu over expression. Patients with low gleason scores (score 6 and 7) and lower grade group (1, 2 & 3) were less likely to have positive EGFR expression as compared to patients with high gleason score (score 9) and higher grade group (5). Similarly, patients with perineural invasion were more likely to have positive EGFR expression. Conclusion: We found a relatively low EGFR expression in our patients with prostatic adenocarcinoma; however, its association with poor prognostic parameters like high gleason score, higher grade group, perineural invasion, higher tissue involvement by cancer and disease recurrence signifies its importance as a prognostic parameter in prostatic acinar adenocarcinoma (AU)