Poor chemotherapy response does not always mean poor breast cancer prognosis
Women with one type of advanced breast cancer who do not seem to benefit from pre-surgical chemotherapy may still fare better in the long-term than women with a more common form of the disease who do respond to chemotherapy, results of a US study indicate.
"This is a striking finding, the first to find that in a type of breast cancer, response to chemotherapy seems to have little to do with long-term treatment success," explained lead researcher Dr Massimo Cristofanilli from the University of Texas.
The findings suggest that the second most common type of advanced breast cancer, called invasive lobular cancer, which develops in the glands that make breast milk, may be a different kind of disease to invasive ductal cancer, the most common form of advanced breast cancer, which develops in the milk ducts between the lobules and the nipple.
Dr Cristofanilli and his team conducted a study of six clinical trials involving more than 1000 women with invasive lobular or ductal cancer who were treated with chemotherapy to reduce their tumours before undergoing surgery.
They found that only 3% of lobular cancer patients had a beneficial response to chemotherapy compared with 15% of ductal cancer patients.
However, 5 years after treatment, breast cancer had not returned in 80% of women with lobular cancer, compared with 66% of ductal cancer patients. Furthermore, survival rates after five years were 91% for the lobular cancer patients compared with 72% in women with ductal cancer.
"We always have thought that a poor response to chemotherapy always indicated a worse prognosis, but that is not true for every woman with breast cancer," said Dr Cristofanilli. "In fact, this study suggests women with invasive lobular carcinoma have a different kind of disease, and that they may benefit from a treatment that is more adequately tailored to the biology of their cancer."
He added that further research is now needed to clarify the unique biological features of invasive lobular cancer so that the most effective treatment can be identified and applied to women with the disease.
The research is published in the Journal of Clinical Oncology.
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