Formestane as Treatment of Advanced Breast Cancer in Elderly Women

The estrogen suppression after sequential treatment with formestane in advanced breast cancer patients

In postmenopausal patients, estrogens have an important role in breast cancer growth and aromatase inhibitors (AI) suppress the aromatase enzyme system which converts androgens into estrogens. The aim of this study was to evaluate the effect on estrogen suppression of formestane 250 mg i.m. fortnightly, given immediately after the failure of a previous treatment with non-steroidal AI. Twenty-two advanced breast cancer patients progressing on letrozole, anastrozole and aminoglutethimide entered the study. At the beginning of the study, the serum estrogen levels were suppressed by the previous treatment with non-steroidal AI, and the following treatment with formestane moderately maintained this suppression; in four patients serum estrogen levels increased fivefold after 10 weeks. Neither complete nor partial responses were observed; 11 patients (50%) showed a stable disease lasting > or = 6 months, and the median time to progression was 6 months (range 3-9 months). No correlation was observed between clinical responses and serum estrogen suppression. Tolerability was satisfactory, and no patient withdrew from the study due to adverse events. In conclusion, formestane has demonstrated a moderate activity in estrogen suppression, and there is evidence that, at the failure of a previous treatment with non-steroidal AI, the sequential use of steroidal AI is feasible. This approach can be used in clinical practice in order to offer a disease control with a satisfactory quality of life.

Formestane is feasible and effective in elderly breast cancer patients with comorbidity and disability

Age is a major risk factor for solid tumors, including breast cancer. The majority of elderly breast cancer patients have oestrogen-dependent tumors, thus, tamoxifen is widely administered. However, it has been noted that tamoxifen-related thrombotic events are not exceptional. Due to the increasing prevalence of comorbidity, including vascular diseases, with age, such events are more frequently observed in the aged patients. Formestane, a selective steroidal aromatase inhibitor, may represent a therapeutic option after failure with tamoxifen, or in the presence of vascular diseases contraindicating its administration. The present report provides a new clinical experience on a consecutive series of 45 elderly breast cancer women affected by moderate to severe degree of comorbidity and disability measured by a Comprehensive Geriatric Assessment (CGA) scale validated on oncological patients. Formestane was given intramuscularly at the dose of 250 mg every 2 weeks. The study included 31 patients who had metastatic disease, and 14 who received formestane as an adjuvant treatment. Median age was 74 years (range 65-93), with nine patients > 80 years. Median ECOG Performance Status (PS) was one. The more frequent comorbidities observed in our series were arthrosis-arthritis (64.4% of patients), hypertension (44.4%), vascular diseases (35.5%), CNS diseases (28.8%). Twenty percent of patients presented at least one dependency in Activities of Daily Living (ADL) and 51.2% in Instrumental Activities of Daily Living (IADL). The treatment was well tolerated - only two patients interrupted formestane because of minor adverse reaction at the injection site and generalised itching. In particular Formestane was not responsible for any worsening of pre-treatment comorbidities, especially hypertension and vascular diseases. Objective responses (OR) were observed in 11.1% of advanced patients, while the disease was stabilised in 51.8% subjects. Median duration of OR was 12 months; median overall survival was 11 months. Among patients receiving formestane as adjuvant treatment, three relapsed, with a time to failure (TTF) of 12 months. Formestane is effective and minimally toxic in an elderly breast cancer population with comorbidities and disabilities measured by CGA.

Steroidal aromatase inhibitors in elderly patients

The choice of treatment for elderly breast cancer patients needs particular care because the presence of physiological functional impairments can modify the drug bioavailability in an unpredictable manner. Hormonal treatment remains one of the choices and, although tamoxifen has proved to be effective in any setting, the use of selective aromatase inhibitors is arousing. Depending on their chemical structure, aromatase inhibitors are either steroidal (such as exemestane and formestane) or non-steroidal (such as letrozole, vorozole and anastrozole). Formestane has been studied in elderly patients with breast cancer and has been found to induce an overall response rate of 51% (95% CI, 35-67%). The drug suppresses estradiol (E2) levels, and changes in other hormones (FSH, LH and SHBG) are observed, but with poor clinical significance, thus confirming its selectivity and potency. Formestane has also been demonstrated to be as effective as tamoxifen. Exemestane and non-steroidal aromatase inhibitors appear to be very promising drugs.