The correct way to calculate the chemotherapy cycle is to calculate the time to receive the next injectable or oral chemotherapy drug from the first day of the injectable or oral chemotherapy drug. For example, a 2-week, 3-week or 4-week chemotherapy regimen is the time between the previous dose and the next actual dose. Each chemotherapy interval is a cycle, in a cycle not every day with chemotherapy drugs, usually the first 1 to 2 weeks of drugs, after 1 to 2 weeks of rest, the purpose is to enable the patient to rest for a short period of time, to wait for the bone marrow function to return to normal levels, but some chemotherapy drugs inhibit the bone marrow later, recovery is slower, so individual programs need 6 weeks to be considered a cycle. A course of chemotherapy refers to 2 to 3 cycles of continuous chemotherapy, and some tumors require 4 to 6 cycles of chemotherapy to be considered as a course of treatment. The purpose is to restore or rebuild the immune function of the patient’s body and to fully regulate the function of the patient’s organs. During this period, the doctor will also advise the patient to use some drugs or nutritional supplements that can improve immune function, and then move on to the next course of chemotherapy if the condition requires it. When doctors ask patients or family members about the number of cycles or courses of chemotherapy, most of them cannot answer correctly and often confuse the two. In practice, we also encounter the situation that when patients ask the medical staff about the correct interval of chemotherapy, the answer they receive may be incorrect.