Weight Loss in an Elderly Colon Cancer Survivor

A 72-year-old man complains that he has been losing weightfor the last 2 months. Colon cancer was diagnosed 2 yearsearlier, and the lesion was resected; he did not receive anyadditional therapy at that time. Except for hypertension,which is well controlled with propranolol, the remainder ofthe medical history is unremarkable.The patient is thin. Temperature is 37.2^oC (98.9^oF);heart rate, 81 beats per minute; respiration rate, 19 breathsper minute; and blood pressure, 138/82 mm Hg. Heart andlungs are normal. The abdomen is soft, with tenderness in theupper region; no organomegaly. Bowel sounds are normal.A CT scan of the abdomen and pelvis is ordered to evaluatethe upper abdominal tenderness and to detect coloncancer recurrence. The liver appears normal in an axial CTimage (Figure 1). Lymph nodes in the periportal regionmeasure 1 cm on short axis, and those in the retroperitoneumare smaller than 1 cm (see Figure 1). These nodes donot meet the CT criterion (greater than 1 cm on short axis)for classification as "pathologically enlarged". However, thepatient's carcinogenic embryonic antigen (CEA) level is 8ng/mL, which strongly suggests colon cancer recurrence; hisCEA level after surgery 2 years earlier was 2 ng/mL.Which diagnostic test would you order next-and why?WHICH TEST-AND WHY: A nuclear medicine fluorodeoxyglucosepositron emission tomography (FDG-PET)scan is ordered to detect colon cancer recurrence.FDG-PET scanning has proved to be highly useful in boththe staging and the restaging of colon cancer.In the initial staging of cancers, PET can effectivelydistinguish between those patients who might benefitfrom an attempt at surgical cure and those with advanceddisease. It is more accurate than CT in this setting.In restaging, PET is also superior to CT-for bothdiagnosis of recurrent disease and localization of the recurrence.The overall sensitivity and specificity of PET fordetecting recurrent colorectal cancer are 100% and 83%,respectively. In this setting, abdominal CT has a sensitivityof 78% and a specificity of 61%.¹ The sensitivity and specificityof measurement of CEA levels are 33% and 86%,respectively.Thus, PET is more accurate than either CT or CEAmeasurement for the detection of recurrent colorectalcancer. PET is also more accurate than CT alone for predictingwhether a recurrence can be resected (82% vs 68%;P = .02).² Moreover, it accurately detects distant metastases and occult secondary malignancies that can affectmanagement decisions.¹Thus, whole-body PET scanning is highly sensitivefor both the diagnosis and staging of recurrent colorectalcancer. Its use-in conjunction with conventional imagingprocedures-results in a more accurate prediction ofwhich patients will benefit from surgical treatment withcurative intent.²What the images reveal. An axial PET image at thelevel of the liver reveals 2 liver lesions that were not identifiedon CT (Figure 2). An axial image at the periportallevel shows increased activity in the periportal region,which is diagnostic of adenopathy at that level (see Figure2). An axial image of the upper abdomen reveals a mesentericmetastasis that was initially overlooked on the CTscan (see Figure 2).Based on these findings, the management strategyfor this patient was changed from possible biopsy of the periportal region of the liver to chemotherapy for widespreadmetastatic disease.

References:

REFERENCES:

1.

Hung GU, Shiau YC, Tsai SC, et al. Value of 18F-fluoro-2-deoxyglucose positronemission tomography in the evaluation of recurrent colon cancer.

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2.

Lonneux M, Reffad AM, Detry R, et al. FDG-PET improves the staging and selectionof patients with recurrent colorectal cancer.

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