Compounds that are PSMA ligands, pharmaceutical compositions comprising these compounds, methods for treating and detecting cancers in a subject, methods for identifying cancer cells in a sample are described herein. Prostate-specific membrane antigen (PSMA) is a 120 kDa protein expressed in prostate tissues and was originally identified by reactivity with a monoclonal antibody designated 7EII-C5 (Horoszewicz et al., 1987, Anticancer Res. 7:927-935; U.S. Pat. No. 5,162,504). PSMA is characterized as a type II transmembrane protein sharing sequence identity with the transferrin receptor (Israeli et al., 1994, Cancer Res. 54:1807-1811).