The purpose of this study is to determine whether there is greater activity for carboplatin than a taxane standard of care (docetaxel) in women with ER-, PR- and HER2- breast cancer. The trial aims to recruit between 370 and 450 patients.

Inclusion Criteria:

• Histologically confirmed ER-, PR-, primary breast cancer
• Histologically confirmed HER2- primary breast cancer
• Measurable confirmed metastatic or recurrent locally advanced disease unsuitable for local therapy but suitable for taxane chemotherapy
• Patients with stable, treated bain metastases will be eligible providing informed consent can be given and that other sites of measurable disease are present.
• Patients with bone metastases currently receiving bisphosphonates for palliation will be eligible providing informed consent can be given and that other sites of measurable disease are present
• ECOG Performance Status 0, 1, or 2
• Adequate haematology, biochemical indices (FBC, U & Es)
• LFTs = Normal bilirubin, AST and/or ALT = 3 x ULN if Alk Phos >5 x ULN (or an isolated elevation AST/ALT of ≤5 x ULN
• Adequate renal function - Creatinine clearance of >25mls per minute
• Written informed consent, able to comply with treatment and follow up

Exclusion Criteria:

• Original primary tumour or subsequent relapse known to be positive for any of ER, PR, or HER2 receptors
• Patients unfit for chemotherapy or those with neuropathy >grade 1 (sensory or motor)
• Known allergy to platinum compounds or to mannitol
• Known sensitivity to taxanes
• Patients with inoperable locally advanced disease suitable for local radiotherapy or an anthracycline containing regimen
• Previous chemotherapy for metastatic disease other than an anthracycline as in inclusion criteria above
• Previous exposure to a taxane in adjuvant chemotherapy within 12 months of trial entry
• Previous treatment with a taxane for recurrent locally advanced disease
• Previous treatment with a platinum chemotherapy drug
• LFTs = Abnormal bilirubin (> ULN), AST and/or ALT >3 X ULN and Alk Phos >5 x ULN (or an isolated elevation AST/ALT of >5 x ULN)
• Patients with a life expectancy of less than 3 months
• Previous malignancies other than adequately treated in situ carcinoma of the uterine cervix or basal or squamous call carcinoma of the skin, unless there has been a disease free interval of at least 10 years
• Previous or synchronous second breast cancer (unless also confirmed ER-, PR- and HER2-)
• Patients with bone limited disease
• Other serious uncontrolled medical conditions or concurrent medical illness likely to compromise life expectancy and/or the completion of trial therapy
• Pregnant, lactating or potentially childbearing women not using adequate contraception