Expression of human epidermal growth factor receptor 2 (HER2) in colorectal cancer and its correlation with clinicopathological characteristic among Jordanian patients

Abstract Introduction/Objective Human epidermal growth factor receptor 2 (HER2/neu) is a well-established therapeutic target in breast and gastric cancers. Currently HER2 expression is being considered in other solid tumors including colorectal cancer (CRC). We aimed to investigate HER2 expression in CRC among Jordanians and its association with clinicopathological variables. Methods/Case Report Formalin-fixed, paraffin-embedded tissue blocks of 69 CRC cases were retrieved with their clinicopathological data. Tissue microarray (TMA) were constructed and immunostained using anti-HER2/neu 4B5 monoclonal antibody (Ventana, Tucson, AZ). HER2 scoring was performed by two experienced pathologists using the HERACLES criteria (HER2 positivity: cases of (3+) in ≥10% of cells and FISH-positive equivocal cases). Fisher’s exact/Chi-square test was used to investigate the association between HER2 s and clinicopathological data such as age, gender, histological differentiation, node and metastasis (NM) stage, and tumor site. Survival analysis was evaluated using Kaplan–Meier curves. Results (if a Case Study enter NA) Any degree (score) of HER2/neu expression was seen in 43.5 % of the cases. In 25 (36.2%), 4 (5.8%) and 1 (1.5%) the HER2 score was 1+, 2+ and 3+ respectively. The rest of the cases, 39 (56.5%) were scored as 0. Two of the four cases with a score (2+) required ISH testing to confirm amplification which was not performed. No significant association was found between HER2/neu expression and clinicopathological parameters or with survival. However, survival analysis showed that combined 2+/ 3+ group tend to have worse overall (OS) and event -free survival than the (0/1+) group. Conclusion The prevalence of HER2 overexpression in CRC is low among Jordanian patients, with only 1.5% of the study sample exhibiting definite HER2 overexpression. This rate is lower than the 3-5% rate reported in general, however the small sample size and lack of FISH confirmation might have contributed to this low rate. There was a trend towards worse OS and EFS in HER2 positive cases