Could the frequency of chemotherapy treatment alter breast cancer survival?

The authors aimed to determine both the effectiveness and toxicity of a type of chemotherapy treatment for breast cancer.

Adjuvant chemotherapy is a course of chemotherapy that patients often receive after their main treatment. Chemotherapy can reduce the risk of cancer recurrence (the cancer returns) and improve overall patient survival.

Improvements upon such treatments are regularly researched. New methods include more frequent doses of adjuvant chemotherapy called dose-dense chemotherapy. Patient outcomes and safety regarding this treatment have yet to be sufficiently evaluated.

A total of 15,785 women with non-metastatic breast cancer (the cancer has not spread to other organs) were evaluated over the course of this review. These women had previously undergone surgical treatments (lumpectomy [removal of tumor and surrounding tissue only] or mastectomy [removal of entire breast]).

Overall, dose-dense chemotherapy improved the patient’s likelihood of survival as they had a 16% reduced risk of death due to breast cancer. This is compared to those treated with conventional chemotherapy regimens.

Hormone receptor status (proteins found on cancer cell surface) of the cancer was an important factor. Women with estrogen receptor negative (ER-) breast cancer had a 20% reduced risk of death following dose-dense chemotherapy, while women with ER+ breast cancer only had a 7% reduced risk. Furthermore, women with human epidermal growth factor receptor 2 positive (HER2+) breast cancer had a further 50% improved chance of survival with the addition of trastazumab (Herceptin) – this drug targets the HER2 receptor.

Assessment of the safety of dose-dense chemotherapy revealed that it was not without side-effects. Anaemia (deficiency in red blood cells) and thrombocytopenia (deficiency of platelets in blood) were both 3 times more likely to occur following dose-dense chemotherapy than with conventional chemotherapy. 

The authors concluded that dose-dense chemotherapy could improve chances of survival, particularly those with ER- breast cancer, with tolerable side-effects.

This review is based upon a limited number of previous studies.