The subject invention addresses the need for methods of treatment and prevention of breast cancer, and other cancers, by providing a peptide of eight to twenty amino acids in length which comprises a hydrophilic analog of an alpha-fetoprotein peptide having SEQ ID NO:6: EMTPVNPG. The peptides may be linear, but are preferably cyclic. The peptides may be provided as dimers or other multimers. A composition comprising the peptide, and antibody that specifically binds to the peptide, a method of reducing estrogen-stimulated growth of cells using the peptides, as well as a method of treating or preventing cancer, such as breast cancer, are also provided. The treatment or prevention method can include the use of tamoxifen therapy in combination with the peptide therapy.
