the cancer cells has led to the development of
a new group of cancer drugs also referred to
as biological therapies, monoclonal antibodies
or targeted therapy. In breast cancer, there are
several targeted therapies in development
(NICE 2011). Trastuzumab is the only
NICE-approved drug available at present in the
NHS. Trastuzumab is a monoclonal antibody
that selectively binds to the HER-2 protein on
the cancer cell, which influences the division
and growth of cancer cells (Langhorne et al
2007). The HER-2 protein or antigen is over
expressed in 15-20% of breast cancers
(Johnston and Swanton 2006) and an
immunohistochemistry test is now performed at
diagnosis of primary breast cancer. Trastuzumab
is given as an infusion either weekly or every
three weeks and treatment continues until
disease progresses outside the central nervous
system (NICE 2009a). Side effects are generally
less severe in comparison with chemotherapy
treatments, but influenza-like symptoms, nausea
and diarrhoea can occur. Patients need to be
made aware of potential side effects and should