An isolated cancer-targeting peptide that includes at least two copies of the amino acid sequence PFLP (SEQ ID NO: 1) or PFLF (SEQ ID NO: 2). Also disclosed is a pharmaceutical composition for treating cancer. The composition contains the isolated cancer-targeting peptide and an anti-cancer agent. Further disclosed is a bispecific anti-cancer antibody that includes the isolated cancer-targeting peptide and an antigen-binding peptide that stimulates T cell activity. Methods are provided for treating cancer by administering the pharmaceutical composition or the bispecific anti-cancer antibody. Further provided is a method for diagnosing cancer by administering a radionuclide-labeled cancer-targeting peptide to an individual and imaging a location of the radionuclide.