Trastuzumab in small tumours and in elderly women

Results of trials assessing the role of trastuzumab in the adjuvant setting in early breast cancer have brought a new standard of treatment to clinical practice. Nevertheless, some groups of patients are underrepresented in these trials and thus therapy should be planned based on incomplete information or lack of solid data. Two of these groups are high-risk HER2+ small tumours (<1cm) and elderly patients. In this review we aimed at addressing the most relevant data about these two populations underrepresented in clinical trials. HER2 overexpression or amplification confers a bad prognosis in patients with small breast tumours. Mammographic screening is increasing the early diagnosis. Taking into account that specific targeted adjuvant treatment can avoid relapses in 50% of HER2-positive patients, about 2 to 7% of relapses from small tumours could be avoided with the use of this treatment. Randomized and non-randomized trials support the idea that adjuvant therapies could improve clinical outcomes of ⩽1cm tumours. Adding a HER2-targeted treatment to chemotherapy may improve efficacy. Some recent data in the neo-adjuvant context suggest that, in some patients, aggressive chemotherapy treatment could be properly substituted by HER2-targeted therapy. In elderly women with HER2+ breast cancer, trastuzumab should be considered for adjuvant-treatment, particularly in those at higher risk of relapse, lack of extra risk factors for trastuzumab-associated cardiotoxicity, and having a prolonged estimated life expectancy. In addition to traditional anthracycline-based combinations commonly used in younger women, other options are the use of sequential chemotherapy, non-anthracycline containing regimes plus anti-HER2 therapies, combinations with hormonotherapy, or even anti-HER2 agents alone.