Malignant tumors are the most common disease worldwide. In recent years, the incidence of malignant tumors has been increasing year by year, which seriously threatens the safety of human life. The occurrence of malignant tumors is a complex process. Therefore, a better understanding of the occurrence and development mechanism of cancer is essential for the prevention, diagnosis, and treatment of cancer. Traditionally, the prognosis of malignant tumors is mainly related to the type and location of tumors, the time of tumor discovery, the degree of malignancy of tumor cells, and whether the treatment is standardized and timely. It is also related to the patient's mentality, reasonable diet, and appropriate exercise. 

Tumor biomarkers refer to specific molecules that can be detected in the blood of cancer patients and can be used as indicators for early diagnosis, prognosis, and monitoring of therapeutic effects. In recent years, with the continuous progress of biotechnology, great progress has been made in the research of tumor biomarkers. Some new technologies can detect very low levels of blood biomarkers and improve the accuracy of early diagnosis of tumors. In addition, some new blood biomarkers such as cfDNA, circulating cancer cells (CTCs), exosomes, microRNAs, etc., have been found to predict the prognosis and treatment effect of cancer. In addition to traditional treatment methods such as surgery, radiotherapy, and chemotherapy, new therapies such as targeted therapy and immunotherapy have emerged, which further improve the prognosis of tumors. With the deepening of the theoretical research on tumor immunity, new therapies based on specific and efficient immune responses have gradually become a hot spot in tumor research. In particular, the emergence of tumor immune checkpoint inhibitors (ICPs) has brought revolutionary changes to tumor treatment. Meanwhile, with the rapid development of artificial intelligence and machine learning technology, radionics has made great breakthroughs. Radiomics has also been used to evaluate and predict the prognosis of malignant tumors. 

The aim of this special issue is to explore and uncover new approaches to improve cancer prognosis.