On the occasion of the granting of research funds for virus based breast anti cancer vaccines, (Oct. 2006) this newspaper article includes comments by a few researchers.
One of them claims that virus based vaccines are likely to be more effective than other approaches.
http://www.myrtlebeachonline.com/mld/myrtlebeachonline/news/local/15658355.htm
However the protein based vaccine approach successfully used in a small brain cancer trial at Duke U. & MD Anderson (http://www.sciencedaily.com/releases...0426075705.htm)
may one day be tried for breast cancer since it uses "epidermal growth factor variant III (EGFRvIII), is found on 30 percent to 50 percent of brain tumors, as well as on some breast and non-small-cell lung cancers, but not on normal tissue"
And it may have few side effect due to the high selectivity 
Linear Mode
