There was no fluctuation of hormone receptor expression within tumour cells during the menstrual cycle (biochemical analysis of oestrogen receptor [ER] and immunohistochemical analysis of progesterone receptor [PR]). HER2, p53, and Bcl2 but not cathepsin D were more commonly expressed in hormone-receptor-negative cases.
In patients with PR-positive cases, HER2 overexpression was seen in 20% (10/50) of tumour samples obtained from patients operated on in the follicular phase of the menstrual cycle and in only 8% (7/84) obtained during the luteal phase (P= 0.05). A similar difference in the frequency of HER2-positivity was seen for ER-positive tumours (20% vs 11%). However, no such change was seen in the PR-negative tumours or for the markers p53, Bcl2 and cathepsin D.
Of the eight cases that had previous needle cores, two cases scored HER2-positive on the specimen removed during the follicular phase and were negative on the specimens removed during the luteal phase. The remaining six cases were either positive or negative on both samples.
Southern blot analysis showed that HER2 gene amplification was present in 9 of 12 hormone-receptor-negative cases and in only 2 of 11 hormone-receptor-positive cases (P = 0.02).