<p>Deuterium, an element recognized for its close association with cancer, is involved in every stage from tumorigenesis and basic research methodologies to clinical diagnosis, therapeutic interventions, and drug development. Several significant findings have emerged in this field. This review explores the potential mechanisms by which deuterons influence cancer initiation and progression in the form of deuterium oxide including deuterium-enriched water (DEW) and deuterium-depleted water (DDW). Besides, deuterium, a stable hydrogen isotope with unique physicochemical properties, also plays a pivotal role in detection and drug discovery. We delve into the importance of deuterium-labeled compound detection techniques—such as hydrogen–deuterium exchange mass spectrometry, deuterium metabolism imaging, Raman deuterium isotope probe techniques, and the applications of AI in Deuterium-related detection techniques—in identifying tumor biomarkers, elucidating metabolic pathways, and validating drug targets. The advantages and limitations of these techniques, particularly in the realm of imaging, are discussed. Deuterium-substituted drugs, such as donafenib, offer notable pharmacokinetic superiorities, including a significantly longer half-life and reduced toxicity compared to conventional chemotherapeutic agents. These characteristics make them promising candidates for cancer chemotherapy. In summary, this review examines the role of deuterium-related molecules in cancer development, detection, and treatment, including DEW, DDW, deuterium-substituted drugs, and deuterium-labeled compounds. Additionally, it highlights the latest advancements in deuterium-labeled compound detection technologies.</p>