The folate receptor (FR) is a cell marker that is over expressed on the cell surface of certain cancers, this occurs most frequently in ovarian cancers. Some normal tissues also express the FR, however in these normal tissues the FR is usually located on the tissue surface that is inaccessible to circulating drugs. As such, drugs which target the FR may potentially be used to achieve anti-tumour efficacy whilst reducing toxicity to normal tissues. Therefore the ability to measure FR levels from different cancer types may help to select patients who are most likely to benefit from treatment with FR targeted therapies. One such drug BGC 945 is currently being tested in preclinical study at The Institute of Cancer Research