Chemotherapy, or chemotherapy for short, is one of the most common treatments for cancer and involves the use of certain drugs to kill cancer cells or to stop them from growing and spreading to other parts of the body. Chemotherapy may be used alone or in conjunction with surgery or radiation therapy, depending on the type, location, size, and stage of the cancer, etc. It is also possible to use some newer anti-cancer drugs along with chemotherapy. Some chemotherapy drugs can be given by mouth, but others must be given by intravenous infusion. To help your body regain strength and fight the side effects of chemotherapy drugs, you may need to take or infuse other drugs in conjunction with your treatment, possibly daily, weekly or monthly, depending on the type and severity of your cancer. Chemotherapy drugs may be given as just one or as a combination of chemotherapy drugs, depending on the type of cancer, history of cancer, and the presence of other underlying conditions, such as heart, kidney, or liver disease. Chemotherapy drugs not only help to destroy, shrink or control the cancer, but sometimes treat symptoms caused by the cancer, such as pain. Why do I need chemotherapy before surgery? 1. To allow some inoperable patients to undergo chemotherapy, which makes the tumor shrink and regains the chance for radical surgery. 2. Pre-operative chemotherapy makes the tumor shrink significantly or even disappear, so that the chance of preserving certain organs can be obtained (such as breast-conserving surgery). 3.Some tumors are highly malignant and metastasis occurs soon after surgery. Through chemotherapy, the tumor is first controlled systemically to avoid bloodstream metastasis, and then surgery is performed for radical treatment to further improve the treatment effect. 4. Pre-operative chemotherapy can be used to determine the efficacy of chemotherapy regimen for patients by measuring the size of tumor visually, but after surgery, the tumor has been removed and the sensitivity of chemotherapy regimen cannot be determined. Why do I need chemotherapy after surgery? Although radical surgery has removed the tumor, the body may still have cancer cells that can grow new tumors or spread the cancer to other parts of the body. Different chemotherapy drugs work in different ways, the main ones are as follows: 1. kill both cancer cells and healthy cells 2. kill only cancer cells 3. prevent the growth of tumor blood vessels and inhibit the progression of tumor 4. attack the genes of cancer cells so that the cancer cells die and cannot grow into new tumors