Review Question - QID 210813

A 54-year-old woman presents to her primary care physician complaining of a lump in her right breast. She first noticed it 1 month ago. Now she is worried that it may have grown. She claims that the lump is not painful or itchy, and she denies any abnormal nipple bleeding or discharge. She has a family history of breast cancer including both her mother and older sister. Her temperature is 98.6°F (37°C), blood pressure is 129/65 mmHg, pulse is 90/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical examination reveals a firm, immobile lump in the upper right breast. A mammogram is performed, which identifies an irregular mass with a fibrotically stranded border. A biopsy is performed that is positive for invasive ductal carcinoma. The patient is started on radiation induction therapy and scheduled for a modified radical mastectomy. Following tumor gene testing, the patient is found to be positive for the HER-2/neu oncogene. Which of the following should be started post-mastectomy to improve the patient’s prognosis?