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HER2-positive tumors account for approximately 18–20% of all breast cancers. These tumors tend to be more aggressive than HER2-negative tumors and are associated with a poorer prognosis. HER2 overexpression, as determined by either 3+ immunohistochemical staining for HER2 protein or HER2 gene amplification by fluorescence in situ hybridization, should be used to select patients for anti-HER2 therapy. Trastuzumab-containing regimens as first-line therapy should be recommended to women with HER2-positive metastatic breast cancer. The continuation of trastuzumab plus capecitabine provided a significant clinical benefit compared with capecitabine alone in women who experienced progression during trastuzumab treatment. An adjuvant trastuzumab-containing regimen should be also recommended to all intermediate- or high-risk women with HER2-positive early breast cancer. Cardiac function should be serially monitored during this treatment. Many anti-HER2 drugs against breast cancer are being developed. The basic mechanisms of their action and resistance emergence are being clarified step by step. Over the mid- or long term, clinical trials comparing these drugs will be conducted until drugs that are clinically effective and easy to use in the true sense survive. Biomarkers are being aggressively searched for concerning individual drugs under development. A position of the “proper drug for the proper patient” will be more firmly established. [ABSTRACT FROM AUTHOR]

Recently, randomized trials revealed that trastuzumab as adjuvant treatment was effective in human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients. Safety information on adjuvant trastuzumab use in Japanese patients, especially cardiac toxicity data, is needed. We retrospectively reviewed 48 patients with early-stage HER2-positive breast cancer who were treated with curative surgery and adjuvant trastuzumab at the National Cancer Center Hospital East (Kashiwa, Japan). The cardiac safety as well as the short-term efficacy of trastuzumab were evaluated. The median age of the patients was 54 years. All patients received adjuvant or neoadjuvant cytotoxic chemotherapy. Twenty-seven patients (56%) received adjuvant radiation therapy. Forty-four patients (92%) received trastuzumab without concurrent cytotoxic chemotherapy and 4 patients (8%) on taxanes received trastuzumab concurrently. Twenty-five patients completed 1 year of trastuzumab treatment and 5 patients completed 2 years of trastuzumab treatment. Nine patients discontinued trastuzumab treatment, because of progressive disease (1 patient), decrease in left ventricular ejection fraction (LVEF; 2 patients), patient’s refusal (4 patients), and other reasons (2 patients). There were five cardiac events. A decrease in LVEF to less than 50% was seen in 2 patients. The relationship between trastuzumab treatment and the cardiac events was unclear in 3 patients. The median follow-up time was 21.2 months. The disease-free survival (DFS) was 97.5% at 1 year and 92.9% at 2 years. The incidence of cardiac events caused by trastuzumab treatment was low in our analysis. Adjuvant trastuzumab treatment for up to at least 1 year should be safe for Japanese breast cancer patients. [ABSTRACT FROM AUTHOR]