Clinical stage 1 cancer. Cancer confined to the intestinal wall mucosa and muscle layer.
Direct cancer clinical stage 2. cancerous invasion and serosal layer, but no lymph node metastasis.
Clinical stage 3 rectal cancer. Serosal cancer over, and there is regional lymph node metastasis.
Cancer clinical stage 4. Cancerous invasion and adjacent organs, distant metastasis and have been widely transferred.