INTESTINE Vol.16 No.4(3-2)


特集名 転移をきたす小さな大腸癌 ─ 本当に悪性の大腸癌とは?
題名 「小さな大腸癌」の特徴(病理の立場から) (2) 小型大腸癌におけるリンパ節転移危険因子の検討
発刊年月 2012年 07月
著者 廣岡 信一 東京慈恵会医科大学病院病理部
著者 池上 雅博 東京慈恵会医科大学病院病理部
著者 野村 浩一 東京慈恵会医科大学病院病理部
著者 原田 徹 東京慈恵会医科大学病院病理部
著者 古里 文吾 東京慈恵会医科大学病院病理部
著者 小山 大河 東京慈恵会医科大学病院病理部
著者 片木 宏昭 東京慈恵会医科大学病院病理部
著者 佐藤 峻 東京慈恵会医科大学病院病理部
著者 柳沢 春華 東京慈恵会医科大学病院病理部
【 要旨 】 リンパ節転移をきたす比較的小型の大腸癌の特徴を明らかにするために,大腸SM癌203例および20mm以下進行癌62例を臨床病理学的に検討した.検討にあたり,buddingはCAM5.2染色,リンパ管侵襲をD2-40染色,静脈侵襲をEVG染色およびCD31染色を用い評価した.SM癌にて,リンパ節転移危険因子として,肉眼的陥凹の有無 ,粘膜内増殖態度(PG, NPG),SM浸潤度(SM1, SM2/3),浸潤部組織型(well/mod, por),buddingの有無(+,-),脈管侵襲(ly and/or v)の6項目を設定し多変量解析を行った結果,もっとも重要な危険因子として取り上げられた項目は脈管侵襲であった(Odds比:9.5).脈管侵襲のリンパ節転移に対する陽性的中率は12.9%,陰性的中率は98.9%であり,脈管侵襲が陰性であれば,ほぼリンパ節転移はないものと考えられた.buddingは,脈管侵襲が正確に評価できない状態(免疫染色で評価できない場合)では有効な指標であった.一方,20mm以下進行癌の検討では,特殊染色によるリンパ管侵襲率は54.8%,静脈侵襲率は56.4%,リンパ節転移率は25.8%であり,いずれもSM癌と比較すると高い値を示した.また,脈管侵襲陰性の病変にはリンパ節転移を認めなかった.すなわち,今回の検索では,リンパ節転移をきたしやすい高悪性度の病変の抽出はできなかったが,少なくとも脈管侵襲のない病変については,リンパ節転移の危険性がきわめて低いことが判明した.
Theme Small colorectal cancer with high malignant potential
Title Risk factors for lymph node metastasis with small colorectal cancer
Author Shinichi Hirooka The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Masahiro Ikegami The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Koichi Nomura The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Toru Harada The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Bungo Furusato The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Taiga Koyama The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Hiroaki Katagi The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Shun Sato The Division of Diagnostic Pathology, The Jikei University School of Medicine
Author Haruka Yanagisawa The Division of Diagnostic Pathology, The Jikei University School of Medicine
[ Summary ] A clinicopathological investigation of 203 cases of submucosal (SM) colorectal cancer and 62 cases of advanced small colorectal cancer (<- 20 mm) was conducted in order to clarify the features of comparatively small colorectal cancers associated with lymph node metastases. Budding, lymphatic vessel invasion and venous invasion were assessed via staining of CAM 5.2, D2-40, and EVG or CD31, respectively. The following six risk factors for lymph node metastasis in SM colorectal cancers were established and multivariate analysis was conducted: presence or absence of gross depressions; intramucosal growth pattern (polypoid or non-polypoid growth); degree of SM invasion (SM1, SM2/3); the histological type of the invasion region (well-differentiated/moderately differentiated, poorly differentiated); presence or ab sence of budding (+/-); and lymphovascular invasion (ly+ and/or v+, ly- and v-). Lymphovascular invasion was demonstrated to be the most important risk factor for lymph node metastasis (odds ratio, 9.5). The positive and negative predictive values for lymph node metastasis with lymphovascular invasion were 12.9 % and 98.9 %, respectively, indicating an association between negativity for vascular invasion and the absence of lymph node metastasis. Budding proved to be an effective marker in cases where vascular invasion could not be accurately evaluated with special staining. Conversely, investigation of advanced small colorectal cancer revealed comparatively high rates of lymphatic vessel invasion (54.8 %), venous invasion (56.4 %) and lymph node metastasis (25.8 %) with special staining compared to SM colorectal cancer cases. Furthermore, lymph node metastases were not observed in lesions that were negative for lymphovascular invasion. Although the present findings did not enable identification of highly malignant lesions susceptible to lymph node metastasis, the risk of such metastases was determined to be extremely low for lesions without lymphovascular invasion.
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