The insensitivity of low-differentiated rectal cancer tumor to chemotherapy may be due to incorrect drug selection, physical factors, pathological types and other reasons. 1. Incorrect drug selection, more drugs can be used in chemotherapy for poorly differentiated rectal cancer, if the drug selection is incorrect, chemotherapy insensitivity will also occur, it is recommended to carry out targeted drug sensitivity test, and select suitable drugs according to the results. 2. Physical factors, physical condition and physical fitness will also affect the chemotherapy results of rectal cancer patients. Generally speaking, chemotherapy results of physically weak patients are not too good, and the condition will continue to aggravate and deteriorate. 3. Pathological type, the malignant degree of low-differentiated rectal cancer is better, no matter the effect of radiotherapy or chemotherapy is not very ideal, and chemotherapy insensitivity will also occur.