The invention relates to colon and prostate tumor associated antigen peptides obtainable from prostate specific G protein-coupled receptor (PSGR), six-transmembrane epithelial antigen of prostate (STEAP) and proteins encoded by genes found overexpressed in colon carcinoma cells, such as human 1-8D interferon induced transmembrane protein 2. The invention further relates to a polynucleotide encoding the tumor associated antigen peptides and to pharmaceutical compositions, which are preferably anti-tumor vaccine compositions, containing a tumor associated antigen, at least one tumor associated antigen peptide thereof, or encoding polynucleotide thereof as an active ingredient. The pharmaceutical compositions can be administered to a patient in need thereof to treat or inhibit the development of colon or prostate cancer.