Evaluation of HER2 and p53 expression in predicting response to docetaxel-based first-line chemotherapy in advanced breast cancer.

Background: The human epidermal growth factor receptor 2 (HER2) and p53 pathways may be involved in chemotherapy sensitivity and/or resistance. We explore the value of HER2 and p53 status to foretell docetaxel sensitivity in advanced breast cancer.

Methods: HER2 and p53 expression was analysed in 36 (median age 55 yrs; range 37-87) metastatic breast cancer patients receiving docetaxel-based first-line chemotherapy. HER2 was determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), p53 was tested by IHC. We correlate the expression of study parameters with pathologic parameters, RECIST response and survival. The standard cut-off value of 2 was used to determine HER2 overexpression while p53 mean expression level was used to divide low/high expressors tumors.

Results: Median time to progression and overall survival were 9 (range 2-54) and 20 (range 3-101) months. Overall response rate was 41.6%. Nine cases showed HER2 overexpression. HER2 was more frequently overexpressed in less differentiated (p=0.05) and higher stage (p=0.003) disease. Mean FISH-HER2 values were significantly higher in responder than in non-responder pts (8.53±10.21 vs 2.50±4.12, p=0.027). Moreover, HER2 overexpression correlates with treatment response at cross-tabulation analysis (p=0.046). p53 expression was only associated with higher stage disease (p=0.02) but lack of any significant association with HER status or docetaxel response. No significant relation with survival was observed for any parameter.

Conclusion: Our data seem to indicate that FISH-determined HER2 status but not p53 is associated with docetaxel sensitivity in metastatic breast cancer.