Even though some studies failed to show a correlation between elevated levels of PAI-1 and poor clinical prognosis [100,101,102], PAI-1 has been established as one of the most reliable biomarkers and prognostic markers in many cancer types, including breast [103,104,105,106], ovarian [107], bladder [108,109], colon [110], renal [111] and non-small cell lung cancers [112]. This evidence concerns the gene SERPINE1 and cancer.