SPARC and esophageal squamous cell carcinoma: SPARC overexpression in primary tumor tissues has since been demonstrated to be significantly associated with poor prognosis in melanoma [9], ESCC [8], non-small cell lung cancer (NSCLC) [10], breast cancer [11], gastric cancer (GC) [12], PDAC [13], CRC [14], and leukemia [15], and prognosis was poor in case of its stromal expression [10,13,14].