PIR and Wilms tumor: For instance, in Wilms tumor, several circulating piRNAs—including piR-hsa-1,913,711, piR-hsa-28,190, piR-hsa-28,849, piR-hsa-28,848, and piR-hsa-28,318—were significantly downregulated in serum samples from patients compared to healthy controls, highlighting their potential for early cancer detection via liquid biopsy [84].