Chemotherapy is one of the important means of treating malignant tumors at present, and efforts to individualize chemotherapy regimens and maximize the effects of chemotherapy are drawing more and more attention from clinicians. The Department of Oncology has carried out in vitro tumor cell culture plus adenosine triphosphate biofluorescence method (ATP-TCA) and individualized treatment of malignant tumors under the guidance of drug sensitivity test, which has achieved very good therapeutic effect and reduced the blindness of chemotherapy. 1. Chemotherapy occupies a very important position in tumor treatment Malignant tumor is a common and frequent disease that seriously endangers human life and health, and is one of the main diseases that lead to disability and early death. In the age group of 35-59 years old, malignant tumor ranks the first cause of death. According to the data, the annual incidence of malignant tumor in China is 2 million, and the death is about 1.5 million, and the rate of increase is 3% and the trend is young, which is the highest mortality rate among all kinds of diseases. At present, the main treatment methods for malignant tumors in the world include surgery, radiotherapy, chemotherapy, endocrine therapy and biological immunotherapy. Among the many means of malignant tumor treatment, chemotherapy, as a systemic treatment method, is more likely to kill the tumor cells in patients’ body to the greatest extent than other methods, therefore, chemotherapy occupies a very important position in malignant tumor treatment. With the development of medicine, chemotherapy is no longer a purely palliative treatment, but is transitioning from palliative to radical treatment. In 1998, the World Health Organization suggested that with appropriate use, chemotherapy has become a radical treatment for curable tumors in some tumors (malignant trophoblastic tumors, acute lymphoblastic leukemia, Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, testicular cancer, acute granulocytic leukemia, embryonal rhabdomyosarcoma, neuroblastoma, small cell lung cancer and ovarian cancer, etc.). Tumors that may be curable with adjuvant chemotherapy include breast cancer, osteogenic sarcoma, colorectal cancer, osteosarcoma, retinoblastoma, soft tissue sarcoma, and nephroblastoma. Chemotherapy plays a palliative treatment role in some advanced tumors, such as prolonging patients’ lives, alleviating symptoms and reducing pain, such as gastric cancer, esophageal cancer, non-small cell lung cancer, head and neck cancer, kidney cancer, melanoma, prostate cancer, endometrial cancer, etc. 2.Factors affecting the efficacy of chemotherapy Although chemotherapy plays a very important role in the treatment of malignant tumors, in clinical practice, the results are often unsatisfactory. Among them, drug resistance of tumor cells to chemotherapy drugs is a common factor leading to the failure of chemotherapy for tumors, and is also a key problem plaguing tumor treatment. Drug resistance is an extremely common clinical problem, and the American Cancer Society estimates that more than 90% of patients who die from tumors are affected by drug resistance in varying degrees. Tumor cell drug resistance is divided into two categories: primary and acquired resistance. The current common clinical practice is to select the most efficacious chemotherapy monotherapy or combination regimen composed of multiple drugs for treatment based on the results of evidence-based studies from international oncology clinical trials, knowing that different chemotherapy drugs have different therapeutic sensitivities for different tumors, i.e., each tumor has a corresponding effective chemotherapy drug sensitivity spectrum. However, in clinical practice, we often encounter the situation that a treatment regimen recognized as effective for a certain tumor by evidence-based research is ineffective for some patients. For example, Adriamycin is a landmark drug for invasive breast cancer, but still 50% of patients with invasive breast cancer are not sensitive to this drug. Another example is Kenzyme, which is recognized to have significant efficacy in non-small cell lung cancer, but also does not work in more than 60% of patients. This is because the tumor is a heterogeneous, polymorphic, and differently differentiated cell population. There are obvious individual differences in tumor response to various chemotherapeutic drugs. That is, different tumor types or different patients of the same type, or even the same patient at different stages of development, do not have exactly the same sensitivity to chemotherapy, and the therapeutic effects vary greatly. So far, there is no chemotherapeutic drug or combination of several chemotherapeutic drugs that can be 100% effective for a certain type of tumor. For this reason, it is important to establish a relatively reliable sensitivity test method, like bacterial sensitivity test, to accurately screen sensitive chemotherapy drugs for different patients and determine their doses, so as to truly realize individualized clinical drug use. 3.Advantages of individualized chemotherapy under the guidance of drug sensitivity In recent years, with the progress of molecular and cell biology research, domestic and foreign scholars are constantly searching for easy, accurate and reliable chemotherapy drug sensitivity testing methods, and more than 10 kinds of drug sensitivity testing methods have been established in two series, in vivo and in vitro. Among them, primary tumor cell culture is one of the most ideal drug sensitivity testing methods so far. This method is characterized by the culture of fresh tumor tissues obtained directly from patients – as the tumor cells have just been isolated from the body, their biological traits have not yet undergone major changes, so it can reflect the characteristics of the whole tumor cell population and the individual differences of different donors more realistically, and can represent the in vivo state more accurately.