Low nuclear grade but not cell proliferation predictive of pathological complete response to docetaxel in human breast cancers

Purpose Predictive factors for response to docetaxel in human breast cancers have yet to be identified. The aim of the present study was to investigate the relationship of various clinicopathological and biological parameters with pathological response to docetaxel in the neoadjuvant setting. Methods The study population comprised 78 patients with primary breast cancers who were treated with docetaxel [60 mg/m(2); four (median) cycles, range 3-6; q3w] as neoadjuvant therapy and subsequently treated with mastectomy or breast conserving surgery. Tumor samples obtained before chemotherapy were subjected to histological examination and immunohistochemistry of HER-2 and Ki-67. Results The pathological complete response (pCR) rate was significantly (P = 0.04) higher for tumors with low nuclear grade (NG-I or -II) (21%) than for tumors with high NG (NG-III) (5%). The pCR rate (20%) of small (<= 5 cm) tumors was marginally significantly (P = 0.05) higher than that of large (> 5 cm) tumors (5%). Combined analysis of NG and tumor size showed that low-NG small tumors have a higher response rate (30%) than high-NG small tumors (11%; P = 0.13), low-NG large tumors (11%; P = 0.15), and high-NG large tumors (0%; P = 0.009). No statistically significant association was observed between pCR rate and menopausal status, lymph node status, ER, PR, HER-2, or Ki-67. Conclusions Low nuclear grade, but not cell proliferation determined by Ki-67, is associated with a good pathological response to docetaxel. Combination of low nuclear grade and small tumor size may be useful for the selection of breast tumors with a high pCR rate (30%).