Colon Cancer Is the Third Term Paper

The second option is worth considering for patients with large or multiple liver lesions because this route results in delivery of a higher dose of chemotherapy to the liver metastases. The underlying principle is that liver metastases derive their blood supply primarily through the hepatic arterial circulation, whereas normal liver derives most of its blood supply through the portal vein. The major adverse effect of intraarterial FUDR is sclerosing cholangitis, which may be quite severe and may necessitate discontinuation of therapy.

Studies have demonstrated a survival advantage for patients with Dukes stage C. colon cancer who receive adjuvant chemotherapy. The 5-FU-based therapy has been administered in the past according to several schedules, including continuous infusion daily for 5 days every 4 weeks (Mayo Clinic regimen) and weekly for 6 weeks with 2 weeks off (Roswell Park regimen).

In terms of patient survival, no study has demonstrated the superiority of daily therapy for 5 days every 4 weeks over weekly therapy for 6 weeks or any other schedule. Thus, the regimens that can be administered on an outpatient basis (weekly for 6 wk with 2 wk off or daily for 5 days every 4 wk) are the most popular and are widely considered to be essentially equivalent.

The classic surgical procedure for colon cancer is anterior resection that involves a "no touch" isolation technique. The abdomen is explored to determine whether the tumor is resectable, and resection is performed segmentally with end-to-end anastomosis. Total colonic resection is performed for patients with familial polyposis and multiple colonic polyps. Although sulindac appears to influence the morphological appearance of polyps in patients with familial adenomatous polyposis, inducing apparent regression at a dose of 200 mg, it does not influence the progression of polyps toward a malignant pattern.

The technology exists to use laparoscopic techniques to achieve colon resection. A recent study reported favorable results with 5 years of follow-up. Sphincter replacement by electrically stimulated skeletal muscle neosphincter and artificial anal sphincter provide a continence option for patients with end-stage fecal incontinence and those requiring abdominoperineal resection.Partial hepatectomy for colon cancer metastases limited to the liver is a therapeutic option for a subset of patients with recurrent colon cancer that appears to be confined to the liver. Some studies have reported an increased median survival duration in highly selected patients. Predictors of a better outcome include a single metastasis, longer disease-free interval from resection of the primary tumor to presentation with metastasis, CEA level less than 200 ng/mL, tumors less than 5 cm in diameter, unilobar disease, and negative margins after resection. Early detection of recurrent colon cancer includes imaging by CT or MRI. CEA levels also may be useful to detect recurrence, although false-positives and false-negatives occur.

Other therapeutic options for liver metastases include cryoablation, a technique currently performed during abdominal surgery, and hepatic arterial infusion (HAI) of chemotherapeutic agents such as FUDR. Adjuvant HAI FUDR is a consideration following partial hepatectomy. An effort is underway to investigate the role of chemotherapy in converting unresectable into resectable disease.

Summary

Cancer of the colon is a serious but easily detected malignancy. Early detection promises a particularly high chance of survival. Most colon cancers start as polyps, which can usually be removed through a colonoscopic exam. Today, there is much that can be done to prevent and cure this cancer. The essential first step involves action by the patient to ensure early detection.

References

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Cappell, M.S. (2005). The pathophysiology, clinical presentation, and diagnosis of colon cancer and adenomatous polyps. Med Clin North Am, 89(1), 1-42, vii.

Guimbaud, R., & Selves, J. (2003). [Detection of hereditary non-polyposis colon cancer (HNPCC)]. J Chir (Paris), 140(6), 317-323.

Huether, S., & McCance, K. (2004). Understanding Pathophysiology. Philadelphia, PA: Mosby.

Kronborg, O. (2004). Colon polyps and cancer. Endoscopy, 36(1),….....