HEADWATERS: Gemcitabine vs Paclitaxel in Metastatic Triple-Negative Breast Cancer in Women of African Ancestry.

The goal of this clinical trial is to learn if Gemcitabine, a chemotherapy drug that is usually used to treat breast cancer after other treatments have failed, is better at treating triple negative breast cancer in women of African ancestry than Paclitaxel, one of the chemotherapy drugs that is usually used first. People will be invited to participate in the trial if they are women of African ancestry, specifically from Jamaica, Barbados and Ghana, are 18 years or older, have had a biopsy that shows that they have triple negative breast cancer (TNBC), and are willing to take part. The main questions the trial aims to answer are: 1. Does Gemcitabine stop triple negative breast cancer from growing or spreading better than Paclitaxel? 2. Are participants more likely to get better when taking Gemcitabine or Paclitaxel? 3. What medical problems do participants have when taking Gemcitabine for breast cancer? 4. Do Gemcitabine and Paclitaxel affect Black women of African Ancestry differently than women from other regions or ethnic groups? To answer these questions, half of participants will be treated with Gemcitabine while half is treated with Paclitaxel. Both drugs are given by injection and have already been approved for breast cancer treatment. Participants will: * Take Gemcitabine for two weeks followed by a two-week break or take Paclitaxel once a week for the same time period. * Have some of the cancer tissue that was tested from their biopsy taken for more testing. * Have a physical exam and a blood test done every 3 weeks. * Have images of their cancer taken using CT (Computed Tomography) or MRI (Magnetic Resonance Imaging) every 6 weeks. * Answer a brief questionnaire about how they are feeling every 8 weeks. * Be checked on every month after treatment is finished to make sure the cancer hasn't come back.