This review outlines the concept of population proteomics and its implication in the discovery and validation of cancer-specific protein modulations. Population proteomics is an applied proteomics sub discipline engaging in the investigation of human proteins across and within populations to define and better understand protein diversity. Population proteomics focuses on interrogation of specific proteins from large number of individuals, utilizing top-down, targeted affinity mass spectrometry approaches to probe protein modifications. Deglycosylation, sequence truncations, side-chain residue modifications, and other modifications have been reported for myriad of proteins, yet little is know about their incidence rate in the general population. Such information can be gathered via population proteomics studies, and would greatly aid the biomarker discovery efforts. Discovery of novel protein modifications is also expected from such large-scale population proteomics studies, expanding the protein knowledge database. In regards to cancer protein biomarkers, their validation via population proteomics approaches is advantageous as mass spectrometry detection is used both in the discovery and validation process, which is essential for the detection of structurally modified protein biomarkers.