The present invention relates to a method of detecting cancer by use of an oncogene, a method of screening for an active compound useful to treat and/or prevent cancer, and a pharmaceutical composition for treatment and/or prevention of cancer. More specifically, the present invention provides a method of detecting cancer based on the expression of the human oculospanin gene as a marker and a pharmaceutical composition containing an antibody capable of specifically recognizing human oculospanin and having cytotoxic activity against cancer cells.