Objective: To study the relationship between tumor infiltration in mesorectum and prognosis of middle and lower rectal cancer.
Methods: 49 patients with middle and lower rectal cancer underwent total mesorectal excision. Specimens were obtained during operation and underwent large slice pathologic technique to observe the degree of tumor infiltration in mesorectum and circumferential resection margin. Follow-up was conducted for 61 (9 - 66) months to observe the local recurrence rate, metastasis rate, and five-year survival rate.
Results: Follow-up showed a local recurrence rate of 12.2% (6/49), distant metastasis rate of 26.5% (13/49), and five-year survival rate of 67.3% (33/49). The rate of degree I of tumor infiltration in mesorectum was 40.8% (20/49), the degree II rate was 26.5% (13/49), and the degree III rate was 32.7% (16/49) with the corresponding local recurrence rates of 0, 7.7% (1/13), and 31.3% (5/16) respectively (chi(2) = 7.357, P = 0.015), metastatic rates of 10% (2/20), 23.1% (3/13), and 50% (8/16) respectively (chi(2) = 7.405, P = 0.025), and the 5-year survival rates of 90% (18/20), 69.2% (9/13), and 37.5% (6/16) respectively. Kaplan-Meier survival analysis showed that the survival time was correlated with the degree of tumor infiltration in mesorectum (P = 0.012). The rate of circumferential resection margin involvement was 24.5% (12/49). In the 12 patients with positive circumferential resection margin, the local recurrence rate was 33.3% (4/12), whereas 5.4% (2/37) in those with negative circumferential resection margin (chi(2) = 6.577, P = 0.010). Distant metastasis rate was 50% (6/12) in the patients with positive circumferential resection margin, whereas 18.9% (7/37) in those with negative one (chi(2) = 4.491, P = 0.034). The 5-year survival rate of the patients with positive circumferential resection margin was 33.3% (4/12), significantly lower than that of the patients with negative circumferential resection margin [78.4% (29/37)]. Kaplan- Meier survival analysis showed survival time was correlated with the circumferential resection margin status (P = 0.009).
Conclusion: The degree of tumor infiltration in mesorectum and circumferential resection margin status are important predictors of local and distant recurrence as well as survival of patients with middle and lower rectal carcinoma.