We prospectively determined serum carcinoembrycnic antigen(CEA) by radioimmunoassay pre-and/or postoperatively in 117 patients with proven colorectal cancer by operation and pathology in order to assess the clinical value of variation in CEA levels before and after surgery. It showed that the courses were later

the incidence of CEA Positivity before operation were higher. Preoperatively the elevated CEA levels were not conclusive evidence in diagnosis of colorectal cancers

but an obvious elevation of CEA level usually showed that the cancer had been in the advanced stageSixty five Patients with colorectal cancers were determined CEA levels only after surgery. When CEA levels elevated obviously or Progressively

it usually showed the recurrence

spread or distant metastasis of disease. CEA levels could also be normal in patients with colorectal cancers in advanced stage.