Although the prognostic significance of PIWIL1 expression has not previously been examined in NSCLC, it has been associated with poor outcome in other tumors, including glioma [26], pancreatic cancer [41], colorectal cancer [42], esophageal cancer [43], liver cancer [44], gastric cancer [45], and sarcomas [25, 46]. This evidence concerns the gene PIWIL1 and colorectal cancer.