PTGS2 and breast carcinoma: Multiple follow-up studies revealed that PTGS2 (COX-2) levels are elevated in many solid tumors, including stomach, esophagus, colorectum, liver, pancreas, lung, and breast cancers (44), and PTGS2 might be employed as an adjunctive therapeutic target for the reversal of chemoresistance in a subset of cisplatin-resistant gastric cancers (45).