Background: The question of whether lymphatic permeation in rectal carcinoma is an index of prognosis remains controversial.
Methods: A long term prospective study of lymphatic permeation of 288 rectal carcinomas was performed. The degree of lymphatic permeation was divided into four stages (Ly0 through Ly3). The median follow-up for the surviving patients was 84 months (range, 23 to 151 months).
Results: In patients with UICC Stage I or II disease, there was no correlation between the Ly0 and Ly1-3 groups' recurrence or survival rates. In patients with Stage IIIa disease, the rate of postoperative recurrence was significantly higher in the Ly1 or Ly2 + Ly3 groups compared with the Ly0 group. The 10-year survival and disease free survival rates in patients with Stage IIIa disease were both 90.0% in the Ly0 group, 63.6% and 62.5% in the Ly1 group, and 52.0% and 45.5% in the Ly2 + Ly3 groups, respectively. A significant difference was noted in the survival rates between the Ly0 and Ly2 + Ly3 groups (P < 0.05), and was noted in the disease free survival rates between the Ly0 and Ly1 (or Ly2 + Ly3) groups (P < 0.05, P < 0.005). In patients with Stage IIIb disease, there were trends toward higher recurrence, lower survival, or disease free survival rates in the Ly2 + Ly3 groups compared with the Ly1 group (P < 0.1).
Conclusions: The degree of lymphatic permeation is an important prognostic factor in patients with Stage III disease, especially in those with Stage IIIa disease. It should be classified as a clinical subgroup.