Predictors of lapatinib responce in her2(+) metastatic breast carcinoma: a retrospective analysis

In patients with HER2(+) metastatic breast carcinoma, there are two options after progression on trastuzumab. First one is changing the cytotoxic agent in thecombination and to continue with trastuzumab, the other is changing the treatment with another anti- HER2 agent lapatinib. There are studies in the literature suggesting that both options are effective but there is no consensus on which one or which patient. In this study we aimed to evaluate factors effecting on lapatinib response, to choose patients who will get benefit from lapatinib.Ninety-four patients treated with lapatinib for metastatic breast carcinoma was included in our study. Retrospective data including pathology, treatments and treatment results, metastatic sites and laboratory tests were collected.There were no factors associated with response to lapatinib, but time to first brain metastasis had a trend to significance. Progression free survival (PFS) was 9,1 months. Histologic subtypes other than invasive ductal carcinoma and liver metastasis was inversely related with PFS. Overall survival (OS) was 22,1 months, and patients with histologic subtypes other than invasive ductal carcinoma and who progress with brain metastasis had a worse prognosis. Clinicians should give attention to histologic subtype and metastatic sites when choosing patients for lapatinib treatment.Key words: Lapatinib, predictors of response, trastuzumab resistance, HER2(+) breast carcinoma