The effect of 3-week tamoxifen treatment on oestrogen receptor levels in primary breast tumours: a flow cytometric study

Abstract

Summary The effect of 3-week, preoperative tamoxifen treatment on oestrogen receptor (ER) levels, expressed by primary breast tumours, was examined. Patients (age-matched) with breast cancer, confirmed by fine-needle aspiration, were either treated with 20 mg ml-' oral tamoxifen per day or received no medication in the 3-week interval between assessment and surgery. Quantification of ER using flow cytometry was performed on the surgically removed tumour samples from tamoxifen-treated (n = 40) and control (n = 38, untreated) patient groups. The tumours were mechanically disaggregated, and saponin treatment rendered these cells permeable to antibodies. Using dualparameter labelling with a FITC-conjugated antibody (NCL-5D3) directed against cytokeratin 8/18/19 and a biotinylated antibody (DAKO-ER 1 D5) directed against the oestrogen receptor, ER quantification was determined on a number of receptors per cell basis. Using QC quantum bead standards, ER levels in the epithelial cell population, the non-epithelial cell population and the whole-cell population (ER +) were calculated. ER levels were significantly lower in the total cell population than tamoxifen-treated patients (P = 0.002) when compared with the control (untreated) group. By using a gating procedure using 5D3 antibody positivity, a significantly lower level was detected on examining the cytokeratin-positive population alone (P = 0.006). Using a complementary gating technique, ER levels were quantified in the cytokeratinnegative cell population. Examination of this group of cells showed no significant difference between the levels of oestrogen receptor found in the tamoxifen-treated and untreated groups (P = 0.4). We have demonstrated that ER levels can be monitored by flow cytometry. ER levels in patients treated with tamoxifen 3 weeks before operation are significantly lower than in a comparative group of patients who received no drug. Furthermore, the most significant difference in receptor levels is seen by quantification of total ER levels expressed by all the tissue.

Effects of tamoxifen on normal breast tissue histological composition: Results from a randomised six‐arm placebo‐controlled trial in healthy women

“…We found that both low‐ and high‐dose tamoxifen reduced the expression of mammary epithelial ER by 5% to 8% in absolute percent difference, respectively, in premenopausal women. Our findings are in line with most previous studies investigating the effects of short‐term tamoxifen in breast tumours of predominantly premenopausal women showing that tamoxifen for up to 6 weeks at various doses significantly reduces the expression of ER in tumours or adjacent tissues 12,14,30‐34 . Our study is the first showing longer‐term effects up to 6 months of tamoxifen in the normal breast epithelium.…”

“…showing that tamoxifen for up to 6 weeks at various doses significantly reduces the expression of ER in tumours or adjacent tissues. 12,14,[30][31][32][33][34] Our study is the first showing longer-term effects up to 6 months of tamoxifen in the normal breast epithelium. In contrast to the association between reduced proliferation and epithelial area, we did not find any association between lower levels of epithelial ER and epithelial area change in women treated with tamoxifen.…”

Growth dysregulation and p53 accumulation in human primary colorectal cancer

“…The cell suspension was divided into two equal portions, one for assessment of cellular DNA content and cell cycle phase fractions and one for the apoptosis assay. We have previously used cytokeratin gating in disaggregated breast cancers after saponin treatment to render cells permeable to antibodies (Brotherick et al, 1998). However, cytokeratin gating and assay of apoptosis in the same sample by the method of the present study is not possible.…”

Multidrug resistance in small cell lung cancer: Expression of P-glycoprotein, multidrug resistance protein 1 and lung resistance protein in chemo-naive patients and in relapsed disease

“…2A). A similar technique of flow cytometric detection of cytokeratin-positive cancer cells was evaluated in breast cancer cells [11,12], in small cell carcinoma [13] and for detection of lymph node metastasis in non-small cell lung carcinoma [14]. The expression of Pgp, MRP1 or LRP was quantified by the percentage of positive cells according to isotype-matched control staining, and the results were scored as the frequency of positive carcinoma cells [15].…”