Small molecules known as microRNAs (miRNAs) are essential for post-transcriptional gene silencing, a process that regulates gene expression. These are tiny RNA molecules that mostly bind to the 3′ untranslated region of mRNA to improve protein translation, which is how they control gene activity at the RNA level. Beyond this, miRNAs affect the cell cycle and general physiological processes by being involved in a number of cellular activities such as development, cell division, signaling, and proliferation. Research indicates miRNAs are significant in cancer initiation and progression, acting either as oncogenes or as tumor suppressors. They also serve as biomarkers for diagnosing and predicting various cancers, with mutations in miRNAs potentially contributing to cancer development. Approximately 30% of all genes and most genetic pathways are controlled by miRNAs, making them key targets for screening, targeted therapies, and understanding disease pathways. Combined with genomics and proteomics, these technologies are crucial for identifying new biomarkers that can enhance cancer screening, early detection, prognosis, and prediction of treatment outcomes, as well as identifying new therapeutic targets. This chapter explores how proteomics and genomics sciences are utilized to analyze molecular changes in cancer and other diseases, aiming to discover candidate biomarkers.