According to the results of a study published in the Annals of Oncology, women with estrogen receptor-negative breast cancer appear to derive the most benefit from adjuvant, anthracycline-based chemotherapy.
Although chemotherapy is recommended for many women with early-stage breast cancer, the benefit of chemotherapy varies. Identifying in advance those women who are most likely to benefit from chemotherapy may allow for more individualized treatment.
Based on characteristics such as estrogen receptor (ER) status and HER2-status, several subtypes of breast cancer have been identified. Because these subtypes have distinct biologic characteristics, they may respond differently to treatments such as chemotherapy.
To explore whether molecular subtype of breast cancer predicts response to adjuvant (post-surgery) anthracycline-based chemotherapy, researchers evaluated information from two breast cancer clinical trials. The trials enrolled a total of 823 patients, and compared outcomes among patients who did and did not receive chemotherapy.
Breast cancers were classified into four subtypes: 1) HER2-positive and ER-negative; 2) basal-like (in addition to other characteristics, basal-like breast cancers are ER-negative, PR-negative, and HER2-negative); 3) HER2-negative, ER-negative, nonbasal; and 4) luminal-like (ER-positive). A majority (66%) of the breast cancers were ER-positive.
- Compared to no chemotherapy, treatment with adjuvant, anthracycline-based chemotherapy significantly improved disease-free survival among women with ER-negative breast cancer (risk of relapse or death was cut in half). In contrast, anthracycline-based chemotherapy did not significantly improve disease-free survival among women with ER-positive breast cancer.
- The benefits of chemotherapy were similar among the three groups of women with ER-negative breast cancer (HER-positive and ER negative; basal-like; and HER2-negative, ER-negative, nonbasal).
The researchers conclude that information about estrogen receptor status provides important information about the likely benefit of adjuvant, anthracycline-based chemotherapy. Women with ER-negative breast cancer appear to derive the most benefit.
Reference: Conforti R, Boulet T, Tomasic G et al. Breast cancer molecular subclassification and estrogen receptor expression to predict efficacy of adjuvant anthracyclines-based chemotherapy: a biomarker study from two randomized trials. Annals of Oncology. 2007;18:1477-1483.
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