Ethinylestradiol is beneficial for postmenopausal patients with heavily pre-treated metastatic breast cancer after prior aromatase inhibitor treatment: a prospective study

• Published in: British journal of cancer Vol. 109; no. 6; pp. 1537 - 1542
• Main Authors: Iwase, H, Yamamoto, Y, Yamamoto-Ibusuki, M, Murakami, K-I, Okumura, Y, Tomita, S, Inao, T, Honda, Y, Omoto, Y, Iyama, K-I
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.09.2013; Nature Publishing Group
• Subjects: 692/699/67/1347; 692/700/565/238; Aged; Aged, 80 and over; Antineoplastic Agents, Hormonal - administration & dosage; Antineoplastic Agents, Hormonal - adverse effects; Antineoplastic Agents, Hormonal - therapeutic use; Aromatase Inhibitors - administration & dosage; Aromatase Inhibitors - therapeutic use; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Breast cancer; Breast Neoplasms - drug therapy; Breast Neoplasms - pathology; Cancer Research; Chemotherapy; Clinical Study; Drug Resistance; Endocrine therapy; Epidemiology; Estrogens - adverse effects; Estrogens - therapeutic use; Ethinyl Estradiol - adverse effects; Ethinyl Estradiol - therapeutic use; Female; Gynecology. Andrology. Obstetrics; Hospitals; Humans; Kaplan-Meier Estimate; Mammary gland diseases; Medical sciences; Metastasis; Middle Aged; Molecular Medicine; Multiple tumors. Solid tumors. Tumors in childhood (general aspects); Neoplasm Metastasis; Oncology; Pilot Projects; Postmenopause; Prospective Studies; Response rates; Thrombosis; Tumors; Japan; aromatase inhibitor resistance; ethinylestradiol; metastatic breast cancer; endocrine therapy; Ethinylestradiol; Human; Breast disease; Aromatase inhibitor; Hormone therapy; Estrogen; Breast cancer; Malignant tumor; Metastasis; Ovarian hormone; Prospective; Resistance; Mammary gland diseases; Cancerology; Postmenopause; Advanced stage; Contraceptive; Sex steroid hormone; Cancer
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/bjc.2013.520

Background: Oestrogens usually stimulate the progression of oestrogen receptor (ER)-positive breast cancer. Paradoxically, high-dose oestrogens suppress the growth of these tumours in certain circumstances. Methods: We prospectively examined the efficacy and safety of ethinylestradiol treatment (3 mg per day oral) in postmenopausal patients with advanced or recurrent ER-positive breast cancer who had previously received endocrine therapies, especially those with resistance to aromatase inhibitors. Results: Eighteen patients were enrolled with the median age of 63 years and the mean observation time of 9.2 months. Three cases withdrew within 1 week due to oestrogen flare reactions with nausea, fatigue and muscle-skeletal pain. The response rate was 50% (9 out of 18), and the clinical benefit rate was 56% (10 out of 18). The stable disease (<6 months) was 17% (3 out of 18) and another 2 cases were judged as progressive disease. Time-to-treatment failure including 2 on treatment was a median of 5.6 months (range 0.1 to 14.5 + ). Although vaginal bleeding or endometrial thickening was observed in patients receiving long-term treatment, there were no severe adverse events, such as deep venous thrombosis or other malignancies. Conclusion: Although the mechanism of this treatment has not been fully understood, our data may contribute to change the common view of late-stage endocrine therapy.