Objective: To investigate the associations between the hormone receptors, Ki67 expression and response to neoadjuvant anthracycline-based chemotherapy in breast cancer patients.
Methods: One hundred sixty-eight primary breast cancer patients received anthracycline-based neoadjuvant chemotherapy. The expression of estrogen receptor (ER), progesterone receptor (PR), and Ki67 were determined by immunohistochemistry assay in core-needle biopsy specimens prior to the chemotherapy, and pathologic response was assessed by Miller & Payne grade (G1 to G5).
Results: 40% (67/168) of the patients had a good pathologic response, defined as complete pathologic response (pCR or G5) and minimal residual disease (G4). Among the patients, 20% (33/168) had a complete pathologic response (G5). ER or PR status was significantly associated with pathological response. Patients with PR-negative tumors had a higher pathological response rate or pCR than those with PR-positive tumors (17/67 vs 45/90, P=0.002; 6/67 vs 25/90, P=0.003, respectively), whereas patients with ER-negative tumors had a higher pathological response rate than those with ER-positive tumors. Moreover, Patients with both ER- and PR-negative tumors exhibited a remarkable pathological response as compared with those with any single factor (36/17 vs 26/86, P=0.009). No association between Ki67 expression and pathological was found in this cohort of patients. There was a linear correlation between the expression of Ki67, ER or PR status and pathologic response.
Conclusion: There is a significant association between the hormone receptors and pathological response to neoadjuvant anthracycline-based chemotherapy in breast cancer patients, and patients with PR-negative tumors are more likely to respond to chemotherapy.