Trastuzumab-induced cardiotoxicity may induce reversible damage that is usually 
transitory and improves with trastuzumab withdrawal. In clinical trials with 
trastuzumab in the adjuvant setting patients with cardiac risks were not 
included. Subgroup analysis identified subpopulations that were most likely to 
experience cardiac damage upon trastuzumab exposure. Although there is a risk of 
cardiac toxicity with adjuvant trastuzumab, the improvement of outcome in 
patients treated with this drug outweighs this. It is essential, therefore, to 
properly assess cardiac function prior to, during and after trastuzumab therapy 
in all patients. The incidence of congestive heart failure in older patients 
treated with trastuzumab is expected to be higher than in the overall population 
evaluated in large clinical trials. Therefore, cardiac risk assessment, breast 
cancer recurrence risk, and discussion between cardiologists and oncologists 
should take place prior to deciding which adjuvant treatment is appropriate for 
a woman with early breast cancer. A longer follow-up period is recommended in 
order to verify whether cardiac reversibility remains and, accordingly, whether 
the short-term risk is exaggerated or understated. With the NSABP-B31 trial 
regimen, the benefit of trastuzumab definitely outweighs the risk; indeed, the 
occurrence of late congestive heart failure after adding trastuzumab to 
chemotherapy is fairly unusual. In the era of personalized medicine, efforts are 
needed to promote strategies for risk detection and management to avoid 
dangerous toxicities that may impede the development of and patient access to 
new agents.