Change in Serum Oestradiol and Testosterone Concentrations After Mastectomy for Breast Cancer with High Aromatase Activity Yuko Tsunoda, 1 Yukiko Shimizu, 2 Akira Tsunoda, 1 Kentaroh Kamiya, 1 Terumasa Sawada, 1 Mitsuo Kusano 1 and Hidekazu Ohta 3 From the 1 Second Department of Surgery, 2 Department of Obstetrics and Gynecology and 3 Second Department of Pathology, School of Medicine, Showa University, Tokyo, Japan Eur J Surg 2001; 167: 234–236 INTRODUCTION Oestrogen has an important effect on the growth of hormone-dependent breast cancer. The concentrations of oestradiol in malignant breast tissue in postmeno- pausal patients were reported to be much higher than expected and were similar to those in premenopausal patients, despite the large difference in serum concen- trations (10). This discrepancy resulted from local oestrogen synthesis, and androgens were converted into oestrogens by aromatase, which was present in skin, muscle, adipose tissue, and the malignant breast tissue (7). There have been many reports about aromatase activity in breast cancer, but to our knowl- edge the change in the serum concentration of oestradiol after mastectomy in patients with breast cancer and aromatase activity has not been reported previously. The present case is interesting in that the serum concentrations of oestradiol fell and testosterone rose dramatically postoperatively. CASE REPORT A 72-year-old woman presented with two masses in the upper outer quadrant of her left breast. Mammography showed two tumours with spicula, and the ultrason- ography of the breast showed two tumours with a maximum diameter of 1.5 cm, which suggested pri- mary cancer. She was treated by modied radical mastectomy. Histological examination showed inva- sive lobular cancer. Her postoperative course was un- eventful, and she had had no recurrence two years later. The surgical specimen was stored at ¡80 ° C, after which the aromatase activity and oestrogen receptor status were measured. For aromatase assays, the tissue was homogenised in four volumes of potassium phosphate buffer (20 mmol potassium phosphate and 1 mmol ethylene diamine tetra-acetic acid, pH 7.5). The homogenates were centrifuged at 1000 g for 20 minutes, and supernatants were used for the assay. The tritiated water assay (9) was used to measure aromatase activity. This assay quantitates the production of tritiated water released from 1 b ¡ [ 3 H] androstenedione after aromatisation. Oestrogen receptors were quantied by enzyme im- munoassay (EIA) from SRL Inc. Co. (Tokyo, Japan). The parafnised specimen was stained with the polyclonal antibody to aromatase (PAbR-9) described by Yoshida and Osawa (11). The immunohistochem- ical staining procedure was the avidin-biotin method. Aromatase activity in the tumours was 950 fmol/mg protein/hour and that of oestrogen receptors was 57 fmol/mg. Aromatase immunoreactivity was seen in cytoplasm of cancer cells (Fig. 1). The serum concen- trations of oestradiol and testosterone were measured preoperatively by radioimmunoassay (RIA) (2), and postoperatively on days 7, 14, and 28. The changes are shown in Fig. 2. The serum concentration of oestradiol was 6.2 pg/ml preoperatively, and postoperatively on days 7, 14, and 28 was 8.2, 2.0, and 2.0 pg/ml, respectively. The concentrations of serum oestradiol decreased during the postoperative period. On the other hand, the serum concentration of testosterone was 16.2 pg/ml preoperatively, and 13.8, 23.8, and 26.3 pg/ ml on postoperative days 7, 14, and 28, respectively. The serum concentration of testosterone increased during the postoperative period. CONCLUSION Aromatase activity measured in human breast cancer homogenates has been reported to be relatively low, at 5–80 fmol/mg protein/hour (3, 4, 8), except by Bez- Ó 2001 Taylor & Francis. ISSN 1102–4151 Eur J Surg 167 CASE REPORT