PROBLEM TO BE SOLVED: To provide a novel diagnosis method of MUC1 positive cancer, and to provide a cancer therapeutic agent effective against MUC1 positive cancer found out by the diagnosis method.SOLUTION: A therapeutic method of cancer comprises administering a therapeutically effective amount of 3,4-dihydroquinazolin 4-one derivative represented by a following formula to a subject in need thereof. A method for diagnosing cancer cells comprises: (i) contacting a population of cells with a MGFR (MUC1 growth factor receptor) specific ligand bound to a signal generating label； and (ii) assaying the binding of the ligand to MGFR on a cell surface, in which presence of uniform signal over the cell surface when contacted with the ligand indicates that the cells are cancerous. [M1-M4 is -CH-CH=CH-CH=CH-, and the like； R1 is a substituted phenyl group and the like； R2 and R3 are each independently a phenylalkyl group and a substituted benzoyl group and the like； R4 and R5 are each independently an H and an alkyl group and the like]COPYRIGHT: (C)2015,JPO&INPIT【課題】ＭＵＣ１陽性癌の新規診断方法及び前記診断方法により見出されたＭＵＣ１陽性癌に有効な癌治療剤の提供。【解決手段】下記式で表される３，４－ジヒドロキナゾリン－４－オン誘導体の治療有効量を、これを必要とする対象に投与することを含む癌の治療方法。癌細胞を診断する方法であって、（ｉ）シグナル生成標識を結合せしめたＭＧＦＲ（ＭＵＣ１成長因子受容体）特異的リガンドに細胞群を接触工程、（ｉｉ）細胞表面のＭＧＦＲへのリガンドの結合を評価分析し、リガンドに接触時に細胞表面全体にシグナルが均一に分布していれば細胞は癌性であると標示されること、を含む方法。［Ｍ１～Ｍ４は－ＣＨ－ＣＨ＝ＣＨ－ＣＨ＝ＣＨ－等；Ｒ１は置換フェニル基等；Ｒ２、Ｒ３は各々独立にフェニルアルキル基、置換ベンゾイル基等；Ｒ４、Ｒ５は各々独立にＨ、アルキル基等］【選択図】なし
