In a patient with breast cancer with negative estrogen and progesterone receptors, which agent should be added to chemotherapy?

In the context of breast cancer treatment, the presence or absence of hormone receptors significantly influences therapy decisions. For a patient with breast cancer that has negative estrogen and progesterone receptors, hormone therapies like letrozole and tamoxifen, which act on these hormone receptors, would not be effective since the cancer does not rely on these hormones for growth.

When considering treatment options, it is important to evaluate other characteristics of the cancer, particularly the HER2 status. If the cancer is HER2-positive, trastuzumab is the recommended agent to be added to chemotherapy. Trastuzumab is a monoclonal antibody that specifically targets the HER2 protein, which is overexpressed in certain breast cancers. This targeted therapy can significantly improve treatment outcomes in patients with HER2-positive disease, even in cases where hormone receptors are negative.

Therefore, in breast cancer patients with negative estrogen and progesterone receptors, adding trastuzumab is a crucial step if the cancer is also determined to be HER2-positive, as it provides a tailored approach that targets the cancer's specific molecular profile.