血管新生の見地からみた食道癌の発育進展

Angiogenesis of Early Stage Esophageal Cancer

要旨　NBI拡大内視鏡で観察される食道病変の微細血管形態の変化を血管新生の見地から文献的に考察した．食道における血管新生の第1のスイッチは，前癌病変よりONになる．食道炎，異型上皮，T1a-EP，T1a-LPM食道癌の血管像は“拡張延長した既存のIPCLと新たに誘導されたIPCL様の幼弱血管の集合（IPCL様異常血管）”であり，その血管形態は典型像はあるものの明瞭な境界は認めない．T1a-MM食道癌以深でみられる血管形態は，いわゆる“腫瘍血管”の条件を満たす（新生血管）．主要な血管新生因子も粘膜下層癌で強発現するものが多く，この時点で血管新生の第2のスイッチが入ると考えられ，食道癌発癌初期に多段階の血管新生が起こっている．

　We discussed the changes in the microvasculature of the various esophageal lesions from a review of the world literature. The initial switching of the angiogenesis for esophageal neoplasia occurs at the precancerous stage. In esophagitis, intraepithelial neoplasia, and M1, M2 cancer, the microvasculature of these lesions should be described as“intermixing of modified IPCL and immature IPCL-like capillaries（IPCL-like abnormal capillaries）”. We encountered the typical microvasculature of each histological situation, however, we could not recognize the apparent border-line between the microvasculature of these lesions.

　As cancer invades deeper than M3, the microvasculature alters its morphology abruptly. The feature of this vasculature is that it fulfills the conditions for so-called tumor vessels（neovasculature）. Major angiogenic factors are activated when the cancer invades the submucosal layer. This is considered to be the second switching of angiogenesis.

　We conclude that multi-step angiogenesis occurs during the early stage of the carcinogenesis of the esophagus.