According to research published early online in the Journal of Clinical Oncology, venlafaxine and clonidine are both effective treatments for the management of hot flushes in women with breast cancer.
The authors note that treatments for breast cancer (e.g. endocrine therapy) may result in hot flushes in both pre- and post-menopausal women; this may be one of the reasons for non-adherence to or early discontinuation of adjuvant therapies. Several agents have been investigated for their ability to modify hot flushes, which are thought to occur as a result of increased noradrenaline and serotonin release, following oestrogen withdrawal. Venlafaxine and clonidine have both been shown in clinical trials to reduce hot flushes and are recommended in clinical guidelines. The purpose of the current study was to compare the efficacy of venlafaxine and clonidine, and both to placebo, for this indication.
A total of 102 women with a history of breast cancer, who had a natural or chemotherapy-induced menopause or were pre-menopausal with suppressed ovarian function, and who experienced at least two hot flushes per day, were randomised to double-blind treatment with venlafaxine 75mg, clonidine 0.1mg, or placebo daily for 12 weeks. Concurrent use of antioestrogens and aromatase inhibitors was permitted if they had been started at least 3 months before entry onto the study. Participants were asked to record the frequency and severity of hot flushes in a diary, and they completed questionnaires assessing scores, sexual function, sleep quality, anxiety, and depression. The primary outcome was daily hot flush scores during week 12.
Baseline hot flush data were available for 95 patients (93%), and week 12 data from 80 patients (78%) were available for analysis (35 patients in the venlafaxine group, 28 in the clonidine group, and 17 patients in the placebo group). The authors report that hot flush scores were lower in the clonidine group than in the placebo group at week 12 (p=0.03); the difference between venlafaxine and placebo was not statistically significant (p=0.07), despite hot flush scores being equal in the clonidine and venlafaxine groups. The differences between both treatments and placebo over the full 12 weeks of the study were statistically significant (P<0.001 for venlafaxine vs. placebo; P=0.045 for clonidine vs. placebo). Treatment-related nausea (P=0.02), constipation (P=0.04), and severe appetite loss were higher in the venlafaxine group.
The authors note that their study was limited by the relatively small number of participants analysed at 12 weeks. They say that their findings, from the first study comparing venlafaxine and clonidine to placebo over a period of 12 weeks, agree with the results of earlier studies of both agents.
An accompanying editorial discusses these and other data regarding the non-oestrogenic management of hot flushes.