In the clinic, many rectal cancers will undergo chemotherapy after surgery, but patients often have low white blood cells after chemotherapy, what is the matter? 1.Why is there low white blood cell? Chemotherapy will inhibit bone marrow hematopoietic system, and rectal cancer patients have low immunity, so chemotherapy will kill white blood cells while killing cancer cells, which is a side effect of chemotherapy. 2.What are the symptoms of low white blood cells? Fatigue and dizziness are the most common symptoms of leukopenia, in addition to loss of appetite, weakness of hands and feet, insomnia, low-grade fever, panic and other symptoms.