Knowing the tumor stage of colon cancer helps us know the extent of tumor invasion in the body, guides our doctors to choose appropriate examinations, and arranges the best treatment for patients.
First of all, we need to understand that the colon is composed of four parts: the ascending colon, the transverse colon, the descending colon and the sigmoid colon, with a total length of about one meter.
Secondly, you must be familiar with the structure of the colon wall. The colon wall is composed of multiple layers of tissue. Tumors originate from the innermost layer that comes into contact with food. This layer is called the mucosal layer. The next layer is the submucosa, which is loose connective tissue. Contains a large number of mucus glands, blood and lymphatic vessels and nerves. The third layer after that is called the muscularis propria. The fourth layer outside the colon is called the serosal layer.
If left untreated, cancer cells can grow through the colon wall into the abdominal cavity and invade structures or organs outside the colon. Cancer cells can also break away from colon tumors and travel through lymph or blood to nearby lymph nodes.
Let's take a closer look at the composition of the American Joint Committee on Cancer (AJCC) TNM staging. T, N, and M are the core three elements, and their respective meanings are:
T (tumor): The extent of tumor invasion into the colon wall N (lymph nodes): Whether there is cancer metastasis in regional lymph nodes M (metastasis): Whether the tumor has spread to areas or organs outside the colon
Different combinations of numbers T, N and M represent a tumor stage. The TNM staging of colon cancer includes five stages: stage 0, stage I, stage II, stage III and stage IV.
Stage 0 (TisN0M0): The cancer cells are still limited to the colon mucosa and have not reached the submucosa, also known as colon cancer in situ. At this stage, simple endoscopic resection can often be effectively treated, and the chance of recurrence is small. Stage I (T1- 2N0M0): The tumor invades the second layer (submucosa) or the third layer (muscular layer) of the colon wall. At this stage, chemotherapy is not required after radical surgery, and regular review is enough. The 5-year survival rate (cure rate) is about 75% .
Stage II (T3-4N0M0): The tumor invades or exceeds the fourth layer of the colon wall (serosal layer). At this stage, a comprehensive consideration is given to whether to give postoperative chemotherapy based on the postoperative genetic status and the presence of high-risk factors. 5-year survival rate Between 40-65%.
Stage III (any T, N1-2M0): The tumor has spread from the colon to nearby lymph nodes, or the tumor has deposited in the fat tissue around the colon to form cancer nodules. At this stage, postoperative adjuvant chemotherapy can clearly reduce the risk of recurrence, and general surgery It starts about 3 weeks after treatment and lasts for half a year.
The 5-year survival rate fluctuates between 30-70%. Stage IV (any T, any N, M1): The cancer has spread to areas outside the colon and nearby lymph nodes. Colon cancer is the most common It often spreads to the liver and lungs. At this time, surgical resection is often difficult, and the main treatment methods are chemotherapy and targeted therapy. The purpose is to prolong the patient's survival time, relieve painful symptoms, and improve the quality of life.