By differentiation, we mean that cells of the same origin gradually give rise to populations of cells with different morphological structures and functional characteristics. Specifically for tumors, this can be understood simply as the degree of maturation of the tumor tissue. The higher the differentiation, the better the cell maturity, i.e., the more it tends to be normal. Therefore, in the pathology report of tumors, the degree of cell differentiation is described to reflect the degree of malignancy of the tumor and the outcome of the patient, etc.
- Highly differentiated gastric cancer, also known as grade I, indicates that the tumor tissue is highly similar to normal human tissue, with high cell maturation and low malignancy; accordingly, this type of gastric cancer is less likely to develop metastasis and has a better outcome after treatment.
- Lowly differentiated gastric cancer, also known as grade III, is the opposite of grade I. The cells are highly malignant, with a higher chance of metastasis, and this type of gastric cancer has a poorer outcome after treatment.
- In between is intermediate differentiation, or grade II, where the cells are between the two in terms of malignancy, chance of metastasis, and outcome.
- Sometimes the tumor cells are so poorly differentiated that no signs of the tissue of origin can be found, and they are called undifferentiated. (Yin Songcheng, Department of Gastrointestinal Oncology, The First Hospital of China Medical University, participated in the answer)