Cancer has been a disease of great concern because it is the second main cause of death in the world. Cures for most cancer pathologies have not yet been found, and an accurate and early diagnosis is essential for successful treatment. Therefore, research on tumor biomarkers has noticeably increased in recent years. The determination of such biomolecules, together with the routinely used laboratory exams for cancer diagnosis, would constitute a more reliable approach, known as systems biology. The "omics" era has corroborated in such investigations since the development of new technologies has arisen along with it. One of the techniques applied to the investigation of tumor biomarkers is CE, and the increasing applications of CE-MS in this field are also observed. This review covers the published literature on tumor biomarker investigations by CE-MS and related techniques, mostly within the last decade, but not limited to it. For didactic reasons this review is divided into the tumor biomarkers chemical classes, namely, proteins and related molecules, DNA adducts and modified nucleosides.