Chemotherapy is a major means of anti-tumor treatment. Some chemotherapy regimens are once a week, some chemotherapy regimens are once every two weeks, but more chemotherapy regimens are once every three weeks. So, why do most chemotherapy regimens have a course of treatment of 21 days? What is the impact of early or late?
Chemotherapeutic drugs act on the cell cycle (prophase of DNA synthesis (G1 phase), DNA synthesis phase (S phase), anaphase of DNA synthesis (G2 phase), and cell division phase (M phase)). The cell cycle of each chemotherapeutic drug is different. Try not to choose the combination of chemotherapeutic drugs that act on the same cycle.
1、 How to calculate the chemotherapy cycle?
The chemotherapy cycle is based on the half-life of the drug and the doubling time of the tumor. It is called a cycle from the first day of the injection of chemotherapy drugs to the 21st or 28th day, that is, 3-4 weeks.
In a cycle, chemotherapy drugs are not used every day, usually in the first to second weeks, and rest in the third to fourth weeks.
The purpose of this is to let the body recover or rebuild the immune function of the body through short-term rest adjustment, so that the functions of various organs can be fully conditioned. During this period, patients should be advised to take some drugs or nutrients to improve immune function.
However, some chemotherapy drugs inhibit bone marrow later and recover slowly. Therefore, individual schemes need 6 weeks to calculate a cycle.
2、 Why is a cycle 21 days?
First of all, how is the 21st calculated?
It is calculated from the first day of injection or oral chemotherapy drugs to the 21st day. For example, paclitaxel plus carboplatin chemotherapy was carried out on September 1, 2021, so the next chemotherapy time is September 22, 2021. The same is true for oral chemotherapy drugs. Oral teggio chemotherapy was carried out on September 1, 2021, so the next chemotherapy time is September 22, 2021.
Most combined chemotherapy regimens are designed according to the time required for the recovery of bone marrow hematopoietic function after cytotoxic drugs damage bone marrow hematopoiesis. The trough of chemotherapy-induced bone marrow suppression, including leukopenia and thrombocytopenia, usually occurs on the 7th-14th day, and then gradually recovers. Most patients can fully recover on the 21st day.
Secondly, can chemotherapy be advanced?
No, early chemotherapy is equivalent to increasing the dose of chemotherapy drugs and increasing the toxic and side effects of chemotherapy drugs.
So, did not carry out chemotherapy on time according to 21 days, and did the delay affect the curative effect by a few days?
Indeed, there may be many reasons for the delay of chemotherapy, such as the failure of white blood cells and platelets to meet the standard, infection, lack of beds, holidays and other reasons. The chemotherapy cycle is set according to the duration of toxic and side effects of chemotherapy drugs, human recovery time and tumor doubling time. Generally speaking, delaying for a few days will not have a great impact on the curative effect, but if multiple chemotherapy are delayed, the curative effect will be affected.
3、 Toxic and side effects of chemotherapy drugs
Chemotherapy drugs will have different degrees of toxic and side effects, common toxic and side effects include: bone marrow suppression, gastrointestinal symptoms, liver and kidney function damage, cardiotoxicity, peripheral neurotoxicity, skin and mucous membrane damage, etc. According to the severity of toxic and side effects, they are divided into different levels. Let's learn together!
Blood system
Digestive tract reaction
Abnormal liver function
Abnormal renal function
Abnormal cardiac function
Abnormal neurological function
Skin and mucosal reaction
other
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https://www.medsci.cn/article/show_article.do?id=5521e318108d
