sign of colon cancer

With proper screening, colon cancer should be detected BEFORE the development of symptoms, when it is most curable.

Most cases of colon cancer have no symptoms. The following symptoms, however, may indicate colon cancer:

· Diarrhea, constipation, or other change in bowel habits that does not resolve

· Blood in the stool

· Unexplained anemia (anemia in any adults other than menstruating women should almost always be evaluated by a colonoscopy)

· Abdominal pain and tenderness in the lower abdomen

· Intestinal obstruction

· Weight loss with no known reason

· Stools narrower than usual

Some citations in the text of this section are followed by a level of evidence. The PDQ editorial boards use a formal ranking system to help the reader judge the strength of evidence linked to the reported results of a therapeutic strategy. Refer to the PDQ levels of evidence summary for more information.

Cancer of the colon is a highly treatable and often curable disease when localized to the bowel. It is the second most frequently diagnosed malignancy in the United States as well as the second most common cause of cancer death. Surgery is the primary treatment and results in cure in approximately 50% of patients. Recurrence following surgery is a major problem and often is the ultimate cause of death. The prognosis of colon cancer is clearly related to the degree of penetration of the tumor through the bowel wall and the presence or absence of nodal involvement. These 2 characteristics form the basis for all staging systems developed for this disease. Bowel obstruction and bowel perforation are indicators of poor prognosis. Elevated pretreatment serum levels of carcinoembryonic antigen (CEA) have a negative prognostic significance. Many other prognostic markers have been evaluated retrospectively in the prognosis of patients with colon cancer, although most have not been prospectively validated. Age greater than 65 years at presentation is not a contraindication to standard therapies; acceptable morbidity and mortality, as well as long-term survival, are achieved in this patient population.

Because of the frequency of the disease, the identification of high-risk groups, the demonstrated slow growth of primary lesions, the better survival of early-stage lesions, and the relative simplicity and accuracy of screening tests, screening for colon cancer should be a part of routine care for all adults starting at age 50 years, especially for those with first-degree relatives with colorectal cancer. There are groups that have a high incidence of colorectal cancer. These groups include those with hereditary conditions, such as familial polyposis, hereditary nonpolyposis colon cancer (HNPCC), Lynch I Syndrome, Lynch II Syndrome, and ulcerative colitis. Together they account for 10% to 15% of colorectal cancers. Patients with HNPCC reportedly have better prognoses in stage-stratified survival analysis than patients with sporadic colorectal cancer, but the retrospective nature of the studies and possibility of selection factors make this observation difficult to interpret.[Level of evidence: 3iiiA] More common conditions with an increased risk include: a personal history of colorectal cancer or adenomas, first degree family history of colorectal cancer or adenomas, and a personal history of ovarian, endometrial, or breast cancer.These high-risk groups account for only 23% of all colorectal cancers. Limiting screening or early cancer detection to only these high-risk groups would miss the majority of colorectal cancers.For more information on this subject, consult the PDQ summaries on screening for colorectal cancer and prevention of colorectal cancer. Following treatment of colon cancer, periodic evaluations may lead to the earlier identification and management of recurrent disease.The impact of such monitoring on overall mortality of patients with recurrent colon cancer is limited by the relatively small proportion of patients in whom localized, potentially curable metastases are found. To date, there have been no large-scale randomized trials documenting the efficacy of a standard, postoperative monitoring program. Postoperative monitoring may detect asymptomatic recurrences that can be resected or metachronous tumors.CEA is a serum glycoprotein frequently used in the management of patients with colon cancer. A review of the use of this tumor marker suggests: that CEA is not a valuable screening test for colorectal cancer due to the large numbers of false-positive and false-negative reports; that postoperative CEA testing be restricted to patients who would be candidates for resection of liver or lung metastases; and that routine use of CEA alone for monitoring response to treatment not be recommended. However, the optimal regimen and frequency of follow-up examinations are not well defined, since the impact on patient survival is not clear.