Venous invasion may predict lymph node metastasis in early rectal cancer.

AIM

The aim of this study was to evaluate the role of histopathological and demographic characteristics in predicting lymph node metastasis in patients with adenocarcinoma of the rectum confined to the mucosal and submucosal layers.

METHODS

Fifty-nine patients with early rectal cancer underwent resection of the rectum including lymph nodes and five showed lymph node metastasis (8.6%). Pathology slides of these patients were reviewed by a single pathologist. Demographic and clinical characteristics of these 59 patients were correlated with the existence of nodal metastasis. Formal tests of comparability were carried out by using Fisher's exact test. Logistic regression models were fitted to data to examine possible relationships with 12 covariates measured from each patient and to obtain corresponding odds ratios (as well as a 95% confidence interval for the odds ratios). These covariates included age at surgery, gender, morphology, histology, degree of differentiation, Haggitt's classification for polyps according to the level of invasion, lymphatic and venous invasion, desmoplastic reaction, degree of lymphocytic invasion, presence of lymphoid follicles and presence of infiltrating or pushing margins.

RESULTS

A significantly higher rate of lymph node metastasis occurs in the presence of venous invasion (P < 0.01). Venous invasion was present in three of five (60%) patients with lymph node metastasis and only four of 54 (7%) patients without lymph node metastasis. Other variables did not achieve statistical significance.

CONCLUSIONS

Only the presence of venous invasion was found to be highly significant. The odds ratio of lymph node metastasis increased 18-fold for a patient who had venous invasion compared with a patient who did not. This suggests that the presence of venous invasion in early rectal cancer may provide valuable information to determine which patients would benefit from radical surgery, or adjuvant radiation therapy after sphincter-sparing surgery owing to an increased risk of lymph node metastasis.