3. To determine the effect of celecoxib on lymphangiogenesis in Nasopharyngeal carcinoma Lymphangiogenesis and factors modulating lymphangiogenesis are associated with clinico-pathological outcome in Nasopharyngeal carcinoma and colorectal cancer. Celecoxib down-regulates lymphangiogenesis Archival colorectal cancer and Nasopharyngeal carcinoma tumor specimens will be obtained from the Department of Pathology. To determine the effect of celecoxib on lymphangiogenesis in Nasopharyngeal carcinoma, the investigators intend to analyze archived specimens collected in a previously conducted study. Colorectal tumor and nodal specimens and Nasopharyngeal carcinoma primary will be examined for MVD, LVD and growth factor expression using established haematoxylin and eosin and immunohistochemical techniques. Quantification of LVD and MVD shall be performed by two pathologists blinded to clinico-pathological variables using standardised methods.