Research Continues to Show Benefit of Chemotherapy After Breast Cancer Surgery

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After surgery to remove early-stage breast cancer, many women are treated with a combination of chemotherapy medicines. If a woman is postmenopausal and the cancer is hormone-receptor-positive, she'll also take hormonal therapy (tamoxifen or an aromatase inhibitor) for 5 years. Treatments given after surgery are called adjuvant therapies and are given to lower the risk of the cancer coming back (recurrence).

Results from studies presented at the 2009 San Antonio Breast Cancer Symposium continued to show the benefits of adjuvant treatments.

One study showed that postmenopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer that had spread to the lymph nodes who got adjuvant chemotherapy AND adjuvant hormonal therapy had a lower risk of recurrence and were more likely to be alive than women who got only hormonal therapy.

The study also showed that starting hormonal therapy after chemotherapy was done was better than giving hormonal therapy and chemotherapy at the same time.

A second study showed that a type of genetic test, called a genomic assay, can help figure out if women diagnosed with early-stage, hormone-receptor-positive breast cancer that has spread to the lymph nodes will benefit from adjuvant chemotherapy. Other research has shown that genomic assays can help figure out if women diagnosed with early-stage, hormone-receptor-positive breast cancer that hasn't spread to the lymph nodes will benefit from adjuvant chemotherapy.

In the first study, 1,477 postmenopausal women diagnosed with hormone-receptor-positive, early-stage breast cancer that had spread to the lymph nodes got one of three adjuvant treatment plans after surgery:

  • tamoxifen alone (no chemotherapy)
  • chemotherapy followed by tamoxifen after chemotherapy was done (sequentially)
  • chemotherapy and tamoxifen given at the same time (concurrently)

The chemotherapy combination was Cytoxan (chemical name: cyclophosphamide), Adriamycin (chemical name: doxorubicin), and methotrexate -- called CAF for short. Most of the women were followed for about 9 years and some were followed for as long as 13 years.

The researchers found that women who got both adjuvant chemotherapy and adjuvant tamoxifen were 24% less likely to have a recurrence than women who got only adjuvant tamoxifen:

  • 57% of the women who got both adjuvant chemotherapy and tamoxifen were alive and with no recurrence compared to 48% of the women who got only adjuvant tamoxifen

Overall survival (with or without a recurrence), was 16% better in the women who got both adjuvant chemotherapy and adjuvant tamoxifen compared to women who got only adjuvant tamoxifen:

  • 65% of the women who got both adjuvant chemotherapy and adjuvant tamoxifen were alive compared to 60% of the women who got only adjuvant tamoxifen

Still, this difference in survival rates wasn't statistically significant, which means it could have been due to chance and not because of the difference in treatment.

Women who got tamoxifen after chemotherapy was done were 16% less likely to have a recurrence compared to women who got tamoxifen at the same time as chemotherapy. This difference also wasn't statistically significant, which means it could have been due to chance and not because of the difference in treatment.

To see if a genomic assay could help figure out if women diagnosed with early-stage, hormone-receptor-positive breast cancer that had spread to the lymph nodes would benefit from chemotherapy after surgery, the researchers tested these types of cancer from 367 women involved in the first study with a genomic assay.

The researchers found:

  • The genomic assay was good at predicting which women who got only adjuvant tamoxifen were more likely to have a recurrence and so would have benefited from adjuvant chemotherapy.
  • The genomic assay also was good at predicting which women who got both adjuvant chemotherapy and adjuvant tamoxifen were less likely to have a recurrence and so could have avoided adjuvant chemotherapy.

So it seems that a genomic assay can help decide if women diagnosed with early-stage, hormone-receptor-positive breast cancer that had spread to the lymph nodes would benefit from chemotherapy after surgery. This is important because it allows women with a low risk of recurrence to avoid chemotherapy and its possible side effects.

If you've been diagnosed with early-stage, hormone-receptor-positive breast cancer, your doctor will probably recommend hormonal therapy (either tamoxifen or an aromatase inhibitor) for at least 5 years after any other treatments are done. You and your doctor also will have to decide if chemotherapy makes sense for your unique situation. If the breast cancer spread to the lymph nodes, this study suggests that you may benefit from chemotherapy before hormonal therapy to lower your risk of recurrence.

Still, if your risk of recurrence is low -- even though the cancer has spread to the lymph nodes -- you and your doctor may want to avoid chemotherapy. As you work through your decision, ask your doctor about the reasons for and against chemotherapy and if a genomic assay could help you make that decision. Armed with the most accurate and up-to-date information about the breast cancer and treatment, you and your doctor can decide on a treatment plan that makes the most sense for you and your unique situation.

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