切除大腸癌からみた右側大腸癌の特徴

The Characteristics of Right-sided Colon Cancer from the Analysis of Resected Specimens

要旨　右側結腸癌と左側結腸癌では，その臨床病理学的因子や予後，遺伝子的背景が異なるとされる．左右結腸癌の違いにつき当科の成績と欧米からの大規模報告の結果を比較した．右側結腸癌は左側に比べ女性の割合が高く，平均年齢が高い．また低分化腺癌や粘液癌の割合が高い．虫垂～上行結腸の癌でその傾向が特に顕著であり，横行結腸癌は上行結腸癌と下行結腸癌の中間の性質を示す．予後については右側結腸癌のほうが左側より悪いとの報告も多いが，最近の大規模報告によれば，リンパ節転移や遠隔転移を伴わないStage I/II症例では左右同等かむしろ左側のほうが不良，Stage III症例では右側のほうが不良，という結果であった．

　It has been reported that the clinicopathological factors or the genetic background of RCCs（right-side colon cancers）differ from those of LCCs（left-side colon cancers）. In this report, we analyzed the differences in the features between the RCCs and the LCCs, surgically resected in our institution, and compared them with those reported in large-scale studies from the United States or European Countries. The percentage of female patients, the mean age and the incidence of poorly differentiated adenocarcinoma or mucinous carcinoma were higher in the RCCs than in the LCCs. These characteristics were more evident in the cancers of the appendix, cecum and ascending colon, and the cancers of the transverse colon showed the intermediate characteristics between ascending and descending colon cancers. Although there are several reports showing a significantly worse prognosis of the RCCs compared to that of the LCCs, consensus has not been achieved. The most recent report revealed a similar or a slightly worse prognosis of the LCCs than the RCCs, when restricted to Stage I/II, i.e, those cases without lymph node or distant metastases, whereas they were worse in the RCCs than the LCCs, when restricted to Stage III.