Objective: Data on hormone receptor and Her2/neu expression in breast cancers from Saudi Arabia and Gulf Region is sparse. We undertook this study to describe the patterns of hormone receptor and Her2/neu protein expression in breast carcinoma and compared them with the histological grade at a university hospital in Riyadh.

Material and Method: We conducted a retrospective hormone receptor and Her2/neu study on 164 histologically confirmed invasive ductal carcinoma of the breast between the year 2002 and 2008. Immunohistochemical analysis for estrogen receptor, progestrone receptor and Her2/neu was done in all the cases. Fluorescent in situ hybridization (FISH) for Her2/neu gene amplification was performed in all 2+ cases and a few equivocal 1+ and 3+cases by immunohistochemistry. The results were then compared in a blinded fashion. Correlation between Estrogen Receptor, Progesterone Receptor and Her2/neu amplification and grade of tumour were calculated.

Result: The prevalence of estrogen receptor, progestrone receptor and Her2/neu overexpression were 64.6%, 57.3% and 35.3% respectively. The expression of estrogen receptor and progestrone receptor were significantly correlated (p<0.001). There was also a significant negative correlation between expression of hormone receptor and Her2/neu amplification. The histological grade of the tumour was also significantly correlated to the expression of both estrogen receptor and progestrone receptor. However, the relationship between Her2/neu amplification and grade of tumour was not significant and many of the grade III tumours were Her2/neu negative. In addition Her2/neu gene amplification by FISH was observed in 84.6% of breast cancers that were 3+ and in 18.75% of the cases that were 2+ by immunohistochemistry.

Conclusion: The revalence of estrogen receptor, progestrone receptor expression and Her2/neu amplification in breast cancers in Saudi Arabian population is similar to that reported internationally. There is a negative correlation between hormone receptors expression and Her2/neu amplification. However, not all high-grade breast cancers showed Her2/neu positive status.