Treatment with anti-ErbB2 antibodies

A method of treating a human patient diagnosed with a breast tumor in which ErbB2 protein is overexpressed comprising the following steps, performed sequentially:

• (a) treating the patient with an anti-ErbB2 antibody that binds to the extracellular domain of ErbB2 protein in an amount effective to reduce size of a tumor in the patient, wherein the antibody is not conjugated to a radioactive isotope;
• (b) surgically removing the tumor;
• and then
• (c) treating the patient with an anti-ErbB2 antibody or a chemotherapeutic agent in an amount effective to reduce the likelihood of disease recurrence in the patient, whereby said human patient is treated.