Buzdar says that because these two breast cancer subtypes behave in dissimilar ways, they also respond differently to chemotherapy treatment. "Estrogen negative cancers are more poorly differentiated and tend to be more sensitive to chemotherapy drugs, and are easier to kill with chemotherapy," he says. "Estrogen receptor-positive breast cancers are differentiated and tend to be less responsive to chemotherapy.

"These results support what has been suspected. Breast cancer patients with estrogen receptor-positive disease may have better likelihood of response to endocrine therapies but the role of chemotherapy in this set of patients needs to be further defined," continues Buzdar. "In the future, we may be able to tell which patients should receive chemotherapy, which should have endocrine treatments, and which might benefit from both."

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4-Dec-2003