A 68-year-old man comes to the office due to fatigue, weight loss, and constipation. He has refused to undergo screening colonoscopy for several years because "nobody in my family had colon cancers." Past medical history is notable for emphysema and stable angina. The patient has smoked a pack of cigarettes daily for 50 years and drinks alcohol occasionally. Physical examination is unremarkable. He is referred for colonoscopy, which reveals a circumferential mass encircling the sigmoid colon. Pathology is positive for adenocarcinoma. CT scan of the chest, abdomen, and pelvis is negative for signs of metastasis. Serum carcinoembryonic antigen assay is ordered. The results of this assay would be most useful for which of the following aspects of this patient's care?

Question

A 68-year-old man comes to the office due to fatigue, weight loss, and constipation.  He has refused to undergo screening colonoscopy for several years because "nobody in my family had colon cancers."  Past medical history is notable for emphysema and stable angina.  The patient has smoked a pack of cigarettes daily for 50 years and drinks alcohol occasionally.  Physical examination is unremarkable.  He is referred for colonoscopy, which reveals a circumferential mass encircling the sigmoid colon.  Pathology is positive for adenocarcinoma.  CT scan of the chest, abdomen, and pelvis is negative for signs of metastasis.  Serum carcinoembryonic antigen assay is ordered.  The results of this assay would be most useful for which of the following aspects of this patient's care?

Quizplus · Accepted Answer

Carcinoembryonic antigen (CEA) is a glycoprotein involved in cell adhesion. It is produced in the embryonic pancreas, liver, and intestine and is also detected in minute amounts in the serum of healthy adults. CEA levels are increased in most patients with colon cancer. Elevated preoperative CEA levels are associated with a worse prognosis, and failure to normalize following surgery suggests residual disease. During long-term follow-up, rising CEA levels are a sensitive indicator of colorectal cancer recurrence. However, CEA has low sensitivity and specificity for initial screening and diagnosis of colon cancer. CEA levels are elevated in pancreatic, gastric, and breast malignancies along with other nonmalignant diseases (eg, inflammatory bowel disease, chronic obstructive pulmonary disease, cirrhosis, pancreatitis). CEA levels are also higher in smokers than nonsmokers. (Choice A) Surgical resection is recommended for most patients with colon cancer unless there are unresectable metastases. The specific procedure recommended is dependent on stage and anatomical considerations rather than CEA levels. (Choice B) Adjuvant chemotherapy is recommended for most patients with node-positive colorectal adenocarcinoma regardless of CEA levels. (Choices C and E) Tumor grade describes the degree of tumor differentiation and is determined histologically. The stage of the tumor reflects the extent of its spread (eg, penetration of the bowel wall, lymph node invasion, distant metastases). Elevated CEA levels are associated with a worse prognosis regardless of tumor stage, but CEA measurement is not currently considered part of the initial staging evaluation. Educational objective: Carcinoembryonic antigen (CEA) levels are increased in colon cancer but are also elevated in a number of other conditions (eg, pancreatic cancer, COPD, cirrhosis). CEA cannot be used to diagnose colon cancer, but it is helpful for detecting residual disease and recurrence. __________ References: Carcinoembryonic antigen in the staging and follow-up of patients with colorectal cancer. (http://www.ncbi.nlm.nih.gov/pubmed/16100946)

A 68-Year-Old Man Comes to the Office Due to Fatigue