Pathological classification of colorectal cancer:
Colorectal cancer is mostly solitary, with multiple occurrences accounting for about 5%. The incidence in the rectum is approximately 65%, in the sigmoid colon about 15%, in the cecum and ascending colon about 10%, in the descending colon and splenic flexure about 5%, and in the transverse colon and hepatic flexure about 5%.
Early-stage colorectal cancer refers to tumors confined to the mucosa or submucosa of the colon, without lymph node metastasis. Macroscopically, it can be classified into three types: polypoid elevated type, flat type, and flat elevated ulcerative type.
Advanced-stage colorectal cancer can be classified into three types:
- Elevated type.
- Ulcerative type. Based on tumor growth pattern and ulcer shape, it can be further divided into two subtypes: localized ulcer type and infiltrating ulcer type.
- Infiltrative type, mostly poorly differentiated adenocarcinoma.
