Currently the gold standard for diagnosis and classification of cancer is based on histopathological examination under the microscope of Hematoxylin and Eosin (H&E) stained slides from cancer biopsies and resected tumors. More targeted examination is based on immunohistochemical examination of a limited number of markers or examination of a limited number of targeted gene expression by in situ hybridization. Although such assays are very valuable to determine the grade and stage of the tumor, they provide limited information on the molecular and cellular content of a tumorigenic lesion, the physiological state of the cells within the lesion, and tumor heterogeneity. However, in many instances the molecular information is pivotal for proper diagnosis and prognosis. Single-cell proteomics is emerging as another powerful approach for phenotypic characterization of individual cells’ type and their physiological state, protein quantitative measurements, and the detection of cancer related post-translational modifications (PTM), that cannot be predicted by genomic/transcriptomic analyses. The National Cancer Institute convened a Think-Tank meeting on the use of single cell proteomics in biomarkers discovery, lesion cartography, disease detection and classification. The Speaker will present the recommendations of this meeting for the benefit of HUPO community and discuss the future potential project for HUPO to consider