Why might one or more fecal occult blood tests be negative, even if the patient has colon cancer?
These tumors frequently bleed intermittently.
How would you evaluate this patient?
Most patients with guaiac positive tests do not have cancer and are bleeding from other gastrointestinal tract problems. At his age, colonoscopy screening is recommended because of the risk for cancer.
Colonoscopy shows a polyp at 30 cm. It is removed by a wire snare. At 50 cm a constricting mass is noted, which is biopsied. Pathology of the polyp shows a tubular adenoma (adenomatous polyp), without invasive cancer. The biopsy of the constricting mass shows adenocarcinoma. How commonly do adenomas and invasive carcinoma co-exist? How common are synchronous multiple primary invasive colon cancers?
About 25% of patients with one tubular adenoma will have a co-existing second tubular adenoma. Only 1-5% of patients with a tubular adenoma will have co-existing invasive cancer. Multiple invasive carcinomas occur at a frequency of 1-2%.
What tests would you order to stage this patient?
Serum laboratory tests can include tests of liver function including bilirubin, ALT, and AST. A serum calcium and alkaline phosphatase may help determine if bone or liver lesions are present. A serum carcinoembryonic antigen (CEA) can be ordered. A CT scan of the abdomen will be done in most cases to look for extent of disease.
A chest X-ray and CT scan of the liver are negative. The serum carcinoembryonic antigen (CEA) is 7.9 (normal 0-5.0). What do you do now? Discuss the indications for surgery with this patient. Explain the role of surgery in a patient with documented liver metastases.
Since there is no evidence for metastatic disease, then there is a good chance that removing the primary tumor will control the cancer. If metastases are present, then the role of surgery is more palliative.
At surgery, a circumferential mass is noted near the splenic flexure. The liver is normal to palpation. A hemicolectomy and mesenteric lymph node dissection are performed. Pathology shows adenocarcinoma in the mass, extending through the muscularis. Three of 10 lymph nodes are positive for tumor. What is the patient's stage?
Stage: T2 N1 M0 (Dukes stage C).
The patient recovers from surgery. His post-op CEA falls to 3.6 (normal for non-smokers is 0 - 3 ng/mL). He receives six months of adjuvant chemotherapy consisting of fluorouracil and leucovorin. What is his prognosis at five years after surgery? How does the chemotherapy improve his prognosis?
His five-year survival is approximately 55-60%, which should increase by 5% with chemotherapy.
What follow-up studies are indicated? What will they look for?
Current guidelines have not been subjected to prospective randomized trials. Colonoscopy at one year and every three years thereafter is recommended on the basis of studies performed on patients with previously detected adenomatous polyps. An elevated CEA generally indicates recurrence.
Three years after surgery, the patient's CEA rises to 6.1 ng/mL. His physical examination continues to be normal. A CT scan of the abdomen shows a single 3 cm mass in the caudate lobe of the liver, which as not present on previous scans. Otherwise the CT scan is unremarkable. A chest radiograph shows no identifiable metastases. A colonoscopy shows no lesions. What do you do now?
Surgical resection of solitary liver metastases (either at the time of diagnosis or in relapse) has been associated with prolonged survival in some patients, although no randomized trials have been performed.
