Predictive factors for response to chemotherapy in advanced breast cancer.

Most breast cancer patients receive chemotherapy at some phase of their illness but only about half of them benefit from it. Identifying the factors predicting response to chemotherapy would also assist the clinician in selection of appropriate patients for chemotherapy, thus saving others from unnecessary exposure to toxic agents. At the present time, there is no tumour biological factor available for clinical use in the prediction of chemotherapy response in advanced breast cancer apart from oestrogen receptor status, which predicts response to hormonal therapy, or the HER2 receptor, which predicts response to trastuzumab. Interestingly, they both are also targets for those therapies. Several groups have tried to find such predictive factors for chemotherapy in advanced breast cancer but the results are so far disappointing. This review collects the rapidly expanding data published so far on the predictive value of tumour biological factors for chemotherapy response in advanced breast cancer. In conclusion, none of them is yet good enough for clinical use in advanced breast cancer.