Researchers have reported that an increased CD9 expression is a favorable survival factor in patients with bladder [18], breast [8, 9], colorectal [10, 11], esophageal [12], head and neck [15, 16], gallbladder [13], lung [17], and pancreatic cancer [14], as well as malignant mesothelioma [19], acute myeloid leukemia [7], and follicular lymphoma [20]. This evidence concerns the gene CD9 and malignant mesothelioma.