Sequential cyclic combined hormonal therapy for metastatic breast cancer

Chains of evidence, mosaics of data: does estrogen 'cause' breast cancer? How would we know?

There appears to be a broad consensus that estrogen is a cause of breast cancer. Proof of cause and effect in clinical medicine requires a different approach for an epidemiological exposure (a 'mosaic' approach) than for an infectious agent suspected of causing a particular disease (a 'chain of evidence' approach). This paper discusses the differences between these two approaches in determining the relationship between a risk factor and a disease, and assesses the strength of the data linking estrogen with breast cancer. Analysis of existing data, including findings from the Women's Health Initiative, finds that all nine of the criteria necessary for confirming the epidemiological strength of a risk factor are not met in the case of estrogen, raising serious questions about the validity of this widespread assumption.

Comparison of the effects of continuous combined and sequential combined medroxyprogesterone acetate-estradiol treatment on the proliferation of MCF-7 cells

OBJECTIVE

The aim of the study was to examine the effects of two different, clinically relevant, hormone replacement therapy (HRT) regimen types, continuous combined and sequential combined, on breast cancer cells by means of an in vitro model. The study was carried out using the C21-progestin medroxyprogesterone acetate (MPA) in combination with estradiol, and with the proliferation of MCF-7, a human breast cancer cell-line, as end-point.

METHODS

Proliferation of MCF-7 cells was measured by means of a crystal violet staining technique. Growth was triggered using a constant estradiol concentration of 10(-10) mol/l, while varying the MPA concentration from 10(-11) to 10(-6) mol/l.

RESULTS

The continuous combined model of treatment led to the inhibition of estradiol-induced growth of MCF-7 with MPA concentrations of 10(-10) mol/l and upwards, compared with estradiol-alone-induced growth. The sequential combined model showed a greater inhibition at the higher MPA concentrations of 10(-8)-10(-6) mol/l, with reduced sensitivity to inhibition at the lower MPA concentrations tested, of 10(-11)-10(-9) mol/l. The different treatment types resulted in significantly different sensitivities of the MCF-7 cells to inhibition of estradiol-induced proliferation at the higher MPA concentrations of 10(-8)-10(-6) mol/l.

CONCLUSIONS

The results demonstrate the importance of considering in vivo factors in an in vitro model with regard to improving the cell culture techniques used, to obtain a clearer picture of the possible mechanisms involved in the potential breast cancer risk with different HRT regimens.

Sequentially administered ethinyl estradiol and medroxyprogesterone acetate in the treatment of refractory epithelial ovarian carcinoma in patients with positive estrogen receptors

The activity of sequentially administered hormonal therapy was investigated over 25 days in 25 patients with epithelial ovarian carcinoma who had estrogen receptor (ERc)-positive tumors. Patients received ethinyl estradiol (EE) (50 micrograms/d) on days 1 to 7 and medroxyprogesterone acetate (MPA) (400 mg/d) on days 8 to 25. Twenty-three patients completed one or more courses of treatment. There were no complete responses (CR). Four partial responses (PR) with durations of 9, 4, 3, and 1 months were seen. Two incomplete responses with durations of 6 and 4 months were also seen. Six patients had stable disease (SD), and 11 patients had progression. The overall response rate was 17% and may represent a modest improvement in response over those in previously published studies conducted with MPA alone. No significant toxic effects were noticed, and some patients reported an improved sense of well-being. However, two patients experienced depression with this treatment. The mean ERc values in responders, patients with SD, and nonresponders were 70.0, 36.7, and 47.9 fmol/mg cytosolic protein, respectively. Future studies of hormonal therapy in patients with ovarian carcinoma should attempt to identify more reliable indices for determining sensitivity to these agents.

Alternating sequential endocrine therapy: tamoxifen and medroxyprogesterone acetate versus tamoxifen in postmenopausal advanced breast cancer patients

The effects of tamoxifen (TAM) versus the alternating sequential combination of TAM plus medroxy-progesterone acetate (MPA) has been evaluated in 20 postmenopausal patients with advanced breast cancer in a randomized controlled trial. In the TAM arm, patients received 20 mg b.i.d. of TAM. In the TAM-MPA arm, patients received only 20 mg b.i.d. of TAM for 7 days and, on the following 7 days. TAM plus an oral daily dose of 500 mg of MPA, in alternating sequence. Objective tumor reduction was achieved in 22 (41%) of the 54 patients in the TAM arm and in 25 (43%) of the 58 patients in the TAM-MPA arm. With regard to the stabilization of disease, a significant difference was observed between patients treated with the TAM-MPA combination and those treated with TAM alone (47% vs 22%). The percentage of nonresponders was also significantly higher in the TAM group (37%) than in the TAM-MPA group (10%). The time to progression was significantly shorter for the TAM arm than for the TAM-MPA arm (median, 7 vs 15 months), but the duration of remission was not significantly different for either treatment.