Clinical History:
- A 56-year-old woman has a routine physical examination performed by her physician, and the only abnormal finding is a positive stool occult blood test. She is referred to a gastroenterologist for a colonoscopy. Laboratory findings include a CBC that shows WBC count 7760/uL, Hgb 12.1 g/dL, Hct 35.2%, MCV 84 fL, and platelet count 209,000/uL. Following colonoscopy with biopsy, a laparotomy with segmental resection of the colon is performed.
- What is your diagnosis?
Adenocarcinoma of the colon, moderately differentiated.
- What do the laboratory test findings in this history suggest?
She has an iron deficiency anemia from chronic blood loss as a result of bleeding from the adenocarcinoma.
- If the lesion extends into the pericolonic fat, what is the Duke's stage?
This is Duke's stage B. If the lesion were confined to the wall of the bowel, then it would be stage A. If lymph node metastases were present, it would be stage C.
- Is there a genetic basis for this condition?
At her age, such a lesion is unlikely to be an inherited genetic disorder such as familial polyposis with the APC gene or hereditary non-polyposis colon carcinoma (HNPCC). However, even sporadic colon carcinomas contain mutations that have collected over years as there is a progression from normal mucosa to adenoma to carcinoma. Such "hits" can include APC (a tumor suppressor gene), abnormal mismatch repair genes (exhibiting microsatellite instability), k-ras (an oncogene), and p53 (a tumor suppressor gene)
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