PIWIL1 and colorectal carcinoma: Interestingly, in the last few years, piRNAs emerged as promising diagnostic and prognostic biomarkers for CRC [14,15,16], where ectopic presence of PIWIL1 has recently been correlated with tumor differentiation status, infiltration, lymph node invasion and metastasis [17,18,19]; patients with PIWIL1 overexpression also showed lower overall survival and disease-free survival [20].