This invention provides a medicament for the treatment of cancer, which cause a reduction of cancer. This invention relates to use of a compound which has inhibitory activities against prostaglandin E2 receptor (EP4 receptor) and is represented by the following general formula (I), (II), (III), or (IV), or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition comprising the compound or the salt for the manufacture of a medicament for the treatment of cancer. The invention relates to a method for treatment of cancer comprising administering the compound or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition comprising the compound or the salt to humans or animals. The compound or a pharmaceutically acceptable salt thereof, or the pharmaceutical composition may be used in combination with one or more second active agents.
