Immunohistochemical expression of oestrogen receptor-α and progesterone receptor in salivary gland tumours

Abstract

Background: The mammary and salivary glands are tubulo-acinar exocrine glands, sharing similar morphological characteristics and tumour histology. It is logical to postulate that they may have similar tumour biology. This study was carried out to define the expression of oestrogen-α (ER-α) and progesterone (PR) in salivary gland tumours (SGTs) presenting at the University College Hospital, Ibadan.

Methods: Formalin-fixed, paraffin-embedded tissue samples of different salivary gland neoplasms were processed for antibodies to ER-α and PR using the specifications of the manufacturer. Two independent investigators reviewed the slides scoring the pattern and intensity of staining as follows: negative (0), weakly positive (+1), moderately positive (+2) and strongly positive (+3). Data were analysed using version 16 of the Statistical Package for Social Sciences (SPSS16). The level of significance was set at P < 0.05.

Results: A total of 40 SGTs from 19 males (47.5%) and 21 females (52.5%) were utilised. There were 15 benign and 25 malignant SGTs. ER expression in benign SGTs was 6.7%, while in malignant SGTs, it was 28.0%. There was no statistically significant difference in the gender and mean age distribution between patients with or without positive ER-α expression (χ(2) = 0.37, P = 0.59 Fisher's exact test; t = 0.054, P = 0.96, respectively). About 66.7% of high-grade SGTs was positive for ER while only 20% of the low-grade lesions were positive.

Conclusion: This study showed that ER-α was expressed more in the high-grade malignant SGTs compared with the low-grade malignant SGTs and the benign SGTs.

Keywords: oestrogen receptor; progesterone receptor; salivary gland tumours.