Cancer is a major health threat facing humanity. One of the difficulties in cancer treatment is its heterogeneity, as tumors vary greatly among different patients, requiring precise treatment based on individual circumstances. In clinical practice, it is extremely important to identify the most effective drugs for the treatment of tumor patients, whether before or after surgery. However, using traditional genetic testing and patient derived xenograft models to screen for therapeutic drugs still faces issues such as insufficient accuracy and long detection cycles. In the process of fighting cancer, is there a way to first create a "simulated battlefield" to select treatment "weapons", determine which drugs are effective for patients, and then let the drugs "go to the battlefield" to implement precise personalized treatment? The construction of an in vitro tumor model is expected to make this idea a reality. Recently, the team led by Associate Professor Yao Rui from the Department of Mechanical Engineering at Tsinghua University summarized the strategy of synergistically applying biological 3D printing technology and organoid technology to the construction of in vitro tumor models, and proposed that this is the most promising development direction in this field. By studying the response of integrated tumor models to different drugs, the most accurate and effective anti-tumor drugs can be quickly screened, which is expected to achieve precise treatment for cancer patients. The relevant research results are published in the journal "Frontier Trends in Biotechnology" under the journal "Cell". The key to selecting the right weapon for personalized tumor treatment through building a "simulated battlefield" outside of the body lies in how close the "simulated battlefield" is to the real environment inside the body. Yao Rui introduced that in order to construct an integrated tumor like model in vitro, the first thing to solve is the biomimetic problem, which aims to restore the real situation of tumor survival in vivo as much as possible. In order to achieve biomimetics, it is necessary to understand the environment in which tumor cells in the body live. Firstly, tumors are abnormal cell proliferation caused by genetic mutations. Mutation not only occurs in the early stages of tumor development, but also accompanies the entire process of tumor progression. Evolving while mutating. Therefore, a major goal of in vitro simulation is to encompass as many stages of tumor progression as possible. Secondly, there are a large number of tumor cells and non tumor cells in the patient's body, which interact with each other. During the simulation process, it is also necessary to replicate the behavior of these population cells. The most important thing is that tumors in the body survive in an organic environment with a complex system of nutrient supply and substance exchange, and researchers need to find ways to simulate this organic system. In order to include various stages of tumor progression in integrated tumor models, Yao Rui's team has been engaged in research on the construction of in vitro tumor models based on biological 3D printing since 2013, and has attempted to use organoids as basic units for biological 3D printing operations. Organoid is a three-dimensional cellular complex that is similar to tissue in the body, has stable phenotypes and genetic characteristics, and can be cultured in vitro for a long time. At present, the main way to form organoids is through cell self-assembly. Organ like technology can break through the simple physical contact between cells, forming closer intercellular biological communication, enabling cell interactions, collaborative development, and the formation of functional mini organs or tissues. The traditional approach of 3D printing in biology is to use a single tumor cell as the raw material, allowing tumor cells to disperse and stack into a three-dimensional structure within the biological material. However, the actual survival within the tumor mass