Our results show that circulating serum oncRNAs captured through a liquid biopsy assay can be used to accurately detect a shared cancer signal in a single, multi-cancer early detection test. We also demonstrate that a multi-modal generative AI model trained on oncRNA profiles can robustly and accurately predict cancer tissue-of-origin within serum for samples with detectable cancer signals. Given the limitations of retrospective studies and the use of frozen, archival samples, we plan to further validate our results in the future through a larger, prospective study.