PG typeとNPG type隆起型早期大腸癌における生物学的悪性度の相違

Differences in Biological Grade between Polypoid Growth and Non-polypoid Growth Types in Protruded Early Colon Cancer

要旨●隆起型大腸pSM癌113病変を対象として，病変の割面形態からPG typeとNPG typeに分け，その生物学的悪性度（組織型，腺腫成分の有無，大きさ，SM浸潤度，脈管侵襲，簇出）を比較検討した．PG type，NPG type共に組織型はすべて分化型であった．PG typeと比較したNPG typeの特徴は，有意に腺腫成分の併存例が少なく，大きさは小さく，SM浸潤距離は深かった．またリンパ管侵襲や静脈侵襲に有意差は認められなかったが，簇出はNPG typeで有意に高頻度であった．これらのことよりNPG typeはPG typeより生物学的悪性度が高い可能性があると考えられた．隆起型早期大腸癌をPG typeとNPG typeに分けることは，両者の生物学的悪性度の相違を表すうえでも有用であることが示唆された．

　On the basis of the cleft morphology of the lesion in protruded submucosal invasive（SM）colon cancer, the lesions in this study was divided into PG（polypoid growth）and NPG（non-polypoid growth）types. For this study, 113 SM colon cancer lesions of either PG or NPG types were compared to determine differences in their biological grade by evaluating histological type, the presence or absence of adenoma component, size, submucosal infiltration, vascular invasion, and budding. Histologically, the lesions of both PG and NPG types are differentiated cancers. However, compared with that in the lesions of PG type, the presence of adenoma component was significantly lower in the lesions of NPG type, which were smaller in size and showed deeper submucosal infiltration. No significant difference was observed in lymphatic and venous invasions for the two types. However, the frequency of budding was significantly higher in the lesions of NPG type, with evidence suggesting that these lesions are more aggressive in early colon cancer. These findings suggest a higher biological grade for the lesions of NPG type than those of PG type, indicating that the classification of protruded early colon cancer into PG and NPG types may help in differentiating the biological grade between the two.