Intensity of tumor budding as an index for the malignant potential in invasive rectal carcinoma

The aim of this study was to quantitatively assess the intensity of tumor budding in rectal carcinoma and to determine how it correlates with the malignant potential.

Intensities of the tumor budding at the invasive front of the surgical specimens from 90 patients (male, 51) with well- or moderately-differentiated rectal carcinoma were investigated. Differences in the budding intensity among pathologic variables were compared, and recurrences and survivals were analyzed in accordance with degree of the budding intensity. The patients ranged in age from 33 to 75 years (mean, 55.4) with the median follow-up being 43 months (range, 12 approximately 108).

Tumor budding was identified in 89 patients (98.9%) with a mean intensity of 7.5+/-5.3. The budding intensity was significantly higher in tumors with lymphatic invasion (p=0.0081), blood vessel invasion (p<0.0001), and perineural invasion (p=0.0013) than in those tumor without these findings. It became significantly higher with the increase in nodal stage (p<0.0001). The intensity of tumor budding in patients with relapse (29 patients) was significantly higher than that in patients without relapse (6.2+/-5.0 vs. 10.2+/-4.9; p=0.0005), but this difference in the intensity was observed only for the node-positive patients (8.0+/-3.4 vs. 11.9+/-5.1; p=0.0064). When the patients were stratified into two groups on either side of the mean of the intensity, the higher intensity group showed a significantly less favorable disease-free (DFS) and overall survival (OS) (p=0.0026 and 0.0205, respectively). Based on the multivariate analysis, the nodal stage and the intensity of budding proved to be the independent variables associated with DFS (p=0.023 and 0.03, respectively).

Tumor budding at the invasive margin is a reliable pathologic index that indicates a higher malignant potential and a less favorable prognosis for patients with advanced rectal carcinoma.