Aromatase inhibitors in post-menopausal metastatic breast carcinoma

To summarise the advances in the hormonal treatment of post-menopausal metastatic breast cancer, this paper reviews the published literature regarding the randomised trials comparing aromatase inhibitors (Als) versus tamoxifen as a first-line therapeutic choice, or Als versus megestrole acetate (MEG) as a second-line option. The pooled analysis of these authors on Al versus MEG as a second-line option for post-menopausal metastatic breast cancer suggested that Als do not add any significant benefit over MEG in terms of overall response rate (ORR) and time to progression. According to the Cochrane Database, use of an Al as a second-line therapy versus any other endocrine therapy (mostly MEG) has shown a significant benefit in terms of overall survival, but not for progression-free survival, clinical benefit (CB) or ORR. Concerning the authors' comparisons between Als versus tamoxifen as a first-line endocrine option in post-menopausal women with metastatic breast carcinoma, Als seem to be superior to tamoxifen, with a significant benefit in terms of ORR, CB and time to progression being observed in favour of Als over tamoxifen with fixed effects estimates. According to the Cochrane Database, there was an advantage to the use of Als over tamoxifen in terms of progression-free survival and CB, but not for overall survival or ORR. With regards to toxicity, Als show similar levels of hot flushes and arthralgia, increased risks of nausea, diarrhoea and vomiting, but a decreased risk of vaginal bleeding and thromboembolic events compared with other endocrine therapies. Weight gain, dyspnoea and peripheral oedema seem to be more frequent with MEG. At present, there is no proved overall survival difference in patients who are treated first with an Al and then with tamoxifen compared with the opposite sequence. In the metastatic setting, results are limited and are based on retrospective analyses.