| 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. |