After surgery for early-stage breast cancer, chemotherapy often is given to destroy any breast cancer cells that may remain in the body and reduce the risk of the cancer coming back (recurrence). Doctors call this type of treatment adjuvant chemotherapy. A number of chemotherapy medicines, given alone or in combination, are used as adjuvant chemotherapy, including a class of medicines called taxanes. Taxol (chemical name: paclitaxel), Taxotere (chemical name: docetaxel), and Abraxane (chemical name: albumin-bound or nab-paclitaxel) are all taxanes.
A study found that taxanes reduce the risk of recurrence of only certain molecular types of breast cancer. So using a taxane to treat the other types of breast cancer doesn't offer any real benefits. The results were reported at the 2009 ASCO Breast Cancer Symposium.
The researchers looked at more than 2,000 early-stage breast cancer tumor specimens using advanced molecular biology technology. Each specimen was put into one of five categories:
- Luminal A tumors are hormone-receptor-positive, HER2-negative, and slow-growing. They were the most common type of tumor (42%).
- Core basal tumors are hormone-receptor-negative, HER2-negative, and positive for other genetic abnormalities (Ki67, CK5/6 and EGFR). They were the second most common type of tumor (24%).
- Luminal B tumors are hormone-receptor-positive, HER2-positive, and fast-growing. They were the third most common type of tumor (18%).
- HER2-positive cancers were the fourth most common type of tumor (12%).
- Aggressive non-basal tumors are hormone-receptor-negative, HER2-negative, and negative for other genetic abnormalities. They were the least common type of tumor (5%).
The researchers reviewed the medical records of the women from whom the specimens were obtained to see if including a taxane in adjuvant chemotherapy reduced the risk of breast cancer recurrence.
Taxanes didn't provide any benefits to women diagnosed with the most common (luminal A) and least common (aggressive non-basal) types of breast cancer. These two types made up 47% of the breast cancers evaluated in the study.
Taxanes offered some benefit to women diagnosed with the other three types of breast cancer (luminal B, core basal, and HER2-positive -- these three types made up 53% of the breast cancers evaluated in the study.) For example, women diagnosed with core basal breast cancer had a 25% lower risk of recurrence when they received a taxane.
These results, along with similar findings from other studies, suggest that a cancer's tumor type should help guide decisions about using taxanes. While some of the tests used in this study aren't routinely done, the information that's typically in a pathology report may be enough to identify the cancer type and help you and your doctor make taxane decisions. Women who are unlikely to benefit from a taxane can avoid the possible side effects, which include nerve pain and other sensory problems (neuropathy).
If chemotherapy will be part of your treatment plan, talk to your doctor about the results of this study. Ask if the cancer's type can be identified using the information in your pathology report and if that cancer type is likely to respond to a taxane. If the information needed to determine cancer type isn't available, ask if you can get that information before any chemotherapy decisions are made. Using all the information available about your specific situation and the best available medical evidence, you and your doctor can make the best choices for you.