The phase I part will enrol patients (in cohorts of 3 or 6) to determine in a step-wise approach, the OTR of lapatinib and docetaxel. Patients should not be entered at a higher dose level until all patients in the previous cohort complete the first cycle of treatment, this first cycle is used to determine OTR. Dose modification of lapatinib will be based on any observed toxicity in the treatment period. The OTR will be defined as the dose level at which £ 1 of 6 patients experiences the DLT (dose limiting toxicity).If no DLT is observed in the first 3 patients at a particular dose level during the first cycle (3 week treatment period), recruitment will start at the next dose levelIf 1/3 patients experiences a DLT at a particular dose level, additional 3 patients will be enrolled at that dose level to a total of 6 patients if no DLT occurred againIf 1/6 patients experiences a DLT at a particular dose level, recruitment will start at the next dose levelIf ³ 2/6 patients experiences the same DLT at a particular dose level, the dose level is not considered to be tolerableIf ³ 2/6 patients experiences two distinct DLT at a particular dose level, additional 3 patients will be enrolled at that dose level to a total of 9 patients. If one of the previously described DLT occurred again among the new enrolled patients, the dose level is not considered to be tolerableA total of 12 patients will be treated at the OTR.The OTR is defined as the dose level at which no more than 1 of 6 patients experiences a DLT.The DLT for this study is defined during cycle 1 for the dose escalation step as:· any grade 3-4 non hematological toxicity as defined by the Common Toxicity Criteria, version 3 (with the exclusion of alopecia, nausea, vomiting, diarrhea, infusion related that can be rapidly controlled with appropriate measures)· an absolute neutrophil count (ANC) < 0.5x109 /L lasting for > = 7 day· febrile neutropenia defined as ANC < 1.0 x109 /L and fever at least 38.5°C· thrombocytopenia < 25, 000/µl or thrombocytopenic bleeding requiring transfusion· grade 3 or higher left ventricular cardiac dysfunction or a ≥ 20% decrease from baseline in left ventricular ejection fraction (LVEF) that is also below the institution's lower limit of normal (LLN), and confirmed by a repeat evaluation 1 to 2 weeks following the first evaluation.