Broadly speaking CRC can be classified according to the extent of their spread – stage and grade
Stage – CRC is classified in 4 stages called TNM stage 1 to 4.
| Stage |
|
Average Survival (%) |
| 1. |
Small cancer within bowel wall |
80 |
| 2. |
Cancer invaded onto the outer surface of the colon wall or adjacent organs |
60 |
| 3. |
Neighbouring lymph nodes infiltrated by cancer |
40 |
| 4. |
Distant metastases e.g. liver metastasis |
20 |
Grade is a measure of aggressiveness of the cancer cells and there are 3 grades, grade 1 (well differentiated, least aggressive), grade 2 (moderately differentiated) and grade 3 (poorly differentiated, most aggressive). Most CRC are in grade 2.
Both the stage and grade is vital in estimating the survival of the patient and in deciding the treatment needed.
Both the stage and grade can only be accurately determined from examination of the tumour specimen under the microscope after surgery.
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