Primary tumors refer to the original site of cancer growth within the body, where cancer initially develops. These tumors can arise in various organs and tissues, such as the lungs, breast, colon, and prostate, among others. Primary tumors can be either benign or malignant, with malignant tumors having the ability to spread to other parts of the body through a process called metastasis. Studying primary tumors is crucial for understanding the development, progression, and treatment of cancer. Researchers investigate various aspects of primary tumors, including their molecular and cellular characteristics, genetic mutations, immune responses, and interactions with the surrounding tissue and microenvironment. This research plays a key role in improving early detection, personalized treatment strategies, and patient outcomes in cancer.