Weak HMGB1 immunostaining was linked to poor histological grade (p < 0.0001), advanced pT stage (p < 0.0001), high UICC stage (p < 0.0001), nodal metastases (p = 0.0108) and distant metastasis (p = 0.0413) in clear cell renal cell carcinomas (ccRCC), invasive tumor growth in urothelial carcinoma (pTa vs. pT2–4, p < 0.0001), mismatch repair deficiency (p = 0.0167) in colorectal cancers, and advanced pT stage in invasive breast carcinomas of no special type (NST; p = 0.0038). This evidence concerns the gene HMGB1 and clear cell renal carcinoma.