HER2-positive, CK5-positive, p53-positive, and COX2-positive breast cancers also often gave rise first to lung metastases (18 (27.3%) of 66 vs. 24 (14.3%) of 168, P = 0.020; 7 (33.3%) of 21 vs. 29 (15.3%) of 189, P = 0.042; 15 (26.3%) of 57 vs. 25 (16.0%) of 156, P = 0.089; and 32 (29.6%) of 108 vs. 25 (20.2%) of 124, P = 0.095, respectively). Here, PTGS2 is linked to breast cancer.