Treatment for women with metastatic breast cancer, that is, cancer that has spread beyond the breast and axilla, usually involves chemotherapy at some point to stop or delay cancer progression. Paclitaxel and docetaxel are chemotherapy drugs known as taxanes. Taxanes work by stopping cancer cells from dividing and reproducing, and their side effects can include nausea, vomiting as well as tingling of hands and feet. In a previous meta-analysis conducted in 2003, a team of Cochrane researchers based in Australia identified a survival benefit for women with metastatic breast cancer who had received taxane-containing chemotherapy compared to women who have received chemotherapy without a taxane. However, at this time, data were available for only 57% of the women included in the studies for the analysis. Ten years later, the team has updated the meta-analysis with data from new studies as well as previously included studies that have observed women for a longer period of time.
The updated Cochrane review includes 28 studies involving 6871 women while the previous analysis included 3643 women. Half of these studies used paclitaxel and the other half used docetaxel; generally, these drugs were given to women every 3 weeks.
The updated analysis showed that taxane-containing chemotherapy gave a modest but significant survival advantage compared to chemotherapy without a taxane; a finding that is consistent with the previous review. If the analysis was restricted to those studies where women received taxanes as the first treatment after diagnosis, this survival benefit persisted. Taxanes also extended the time without further progression of cancer and caused tumours to shrink more than chemotherapy without taxanes. However, taxanes were associated with an increased risk of neurotoxicity and hair loss but less nausea and vomiting compared to non-taxane chemotherapy. Of the studies that reported quality of life measures, there did not appear to be any difference in a woman’s quality of life when receiving taxane or non-taxane chemotherapy.
Overall, there is now sufficient evidence confirming the benefits and side effects of taxanes in the treatment of metastatic breast cancer. The Cochrane researchers do not intend to do future updates of this analysis. Senior author, Associate Prof Nicholas Wilcken highlighted that, “There is more and more emphasis on the different biological subtypes of breast cancer and there is a rapidly developing array of targeted therapies to be used in place of or as adjuncts to cytotoxic chemotherapy. If future trials examine either the role of taxanes in specific subtypes of breast cancer, or the role of taxanes together with or versus targeted therapies, then a new Cochrane review will be warranted.”
Link to the Review: http://onlinelibrary.wiley.com/enhanced/doi/10.1002/14651858.CD003366.pub3
[Cover image: foliage of the Yew tree. Taxanes were originally derived from the Yew tree]