Long-Term Complete Response with Single-Agent Capecitabine in Her-2-neu-Positive Metastatic Breast Cancer-A Rare Case Report.

The standard treatment approach for metastatic breast cancer with HR- and Her-2-neu + disease is trastuzumab with systemic therapy. But in patients having severe cardiac dysfunction, trastuzumab is avoided. Various combination regimens are available in that setting, but no study has shown better efficacy of capecitabine monotherapy in this setting. We hereby present a case report of using capecitabine monotherapy in first-line setting, and the patient had complete resolution of lung metastasis from the last 2 years. A 64-year-old postmenopausal lady with a known case of breast carcinoma in the left side diagnosed in the year 2016 with hormone receptor-positive, Her2-negative disease completed chemoradiation and on is aromatase inhibitor from the last 5 years. She complained of breathlessness and fatigue lasting for 1 month in July 2021. On evaluation, chest CT scan revealed multiple bilateral lung metastases along with 3×3 cm right-sided breast lump with no metastasis elsewhere in the body. Core needle biopsy of breast lump and CT-guided left lung nodule biopsy were performed which revealed infiltrating carcinoma with immunohistochemical markers showing tumor cells positive for Her-2-neu with hormone receptor-negative disease. PET-CT scan was done which revealed FDG avidity in bilateral lung fields and right breast lump with no disease elsewhere. Her echocardiography showed ejection fraction of 40% owing to which injection trastuzumab was deferred and the plan to start tablet capecitabine 1000 mg twice BD days 1-14 cycles every 21 days was made. She showed improvement in symptoms with PET-CT scan revealing resolution of lung metastasis from the last 2 years. Trastuzumab in combination with pertuzumab and taxane is the standard of care for metastatic breast carcinoma with hormone receptor-negative and Her2-positive disease. But in patients who are elderly, frail with severe cardiac dysfunction, trastuzumab-based regimen is contraindicated. No study demonstrated efficacy of capecitabine monotherapy in this subset of disease. More prospective studies are required to identify patients who can benefit from capecitabine monotherapy in first-line setting in this subset of disease. Also capecitabine usage has several advantages mainly low cost and availability in oral form, and patients can be followed up on OPD basis.