[Mesorectal metastasis of middle and lower rectal cancer]

To detect mesorectal metastasis of middle and lower rectal cancer and to evaluate its relationship with clinicopathologic characteristics.

Cancer specimens resected from 56 patients with middle and lower rectal cancer who received total mesorectal excision were examined by routine pathologic observation. The relationship between mesorectal metastasis and clinicopathologic characteristics of middle and lower rectal cancer was also investigated.

Mesorectal metastasis was detected in 36 (64.3%) of 56 cancer specimens. In 18 cancer specimens with tumor diameter > or = 5 cm, 15 (83.3%) were detected mesorectal metastasis, while in 38 cancer specimens with tumor diameter < 5 cm only 21 (55.3%) were detected mesorectal metastasis (P = 0.041). Mesorectal metastasis was more frequent in T(3) cancer specimens (81.5%) and T(2) cancer specimens (56.6%), compared with T(1) cancer specimens (1/6) (P = 0.007). 85.7% poorly differentiated cancer specimens were detected mesorectal metastasis, while moderate and well-differentiated cancer specimens were only 63.2% and 1/5 respectively (P = 0.028). Mesorectal metastasis was more frequent in stage III cancer specimens (100%), compared with stage II and I cancer specimens (27.3% and 1/5 respectively, P = 0.000). No significant correlations were found between mesorectal metastasis and other variables such as age, gender and Ming classification (P > 0.05).

Mesorectal metastasis of middle and lower rectal cancer has significant correlation with tumor diameter, tumor invasion, tumor differentiation and TNM stage. Total mesorectal excision or > or = 5 cm mesorectal distal to the rectal tumor should be followed in the management of middle and lower rectal cancer.