General Information

About Colon Cancer

Cancer of the colon is a highly treatable and often curable disease when localized to the bowel. Surgery is the primary form of treatment and results in cure in approximately 50% of the patients. Recurrence following surgery is a major problem and is often the ultimate cause of death.

Incidence and Mortality

Estimated new cases and deaths from colon cancer in the United States in 2017:[1]

• New cases: 95,520 (colon cancer only).
• Deaths: 50,260 (colon and rectal cancers combined).

Gastrointestinal stromal tumors can occur in the colon.

Risk Factors

Increasing age is the most important risk factor for most cancers. Other risk factors for colorectal cancer include the following: ·

• Family history of colorectal cancer in a first-degree relative.[2]
• Personal history of colorectal adenomas, colorectal cancer, or ovarian cancer.[3-5]
• Hereditary conditions, including familial adenomatous polyposis (FAP) and Lynch syndrome (hereditary nonpolyposis colorectal cancer [HNPCC]).[6]
• Personal history of long-standing chronic ulcerative colitis or Crohn colitis.[7]
• Excessive alcohol use.[8]
• Cigarette smoking.[9]
• Race/ethnicity: African American.[10,11]
• Obesity.[12]

Screening

Because of the frequency of the disease, ability to identify high-risk groups, slow growth of primary lesions, better survival of patients with early-stage lesions, and relative simplicity and accuracy of screening tests, screening for colon cancer should be a part of routine care for all adults aged 50 years and older, especially for those with first-degree relatives with colorectal cancer.

Prognostic Factors

The prognosis of patients with colon cancer is clearly related to the following:

• The degree of penetration of the tumor through the bowel wall.
• The presence or absence of nodal involvement.
• The presence or absence of distant metastases.

These three characteristics form the basis for all staging systems developed for this disease. Other prognostic factors include the following:

• Bowel obstruction and bowel perforation are indicators of poor prognosis.[13]
• Elevated pretreatment serum levels of carcinoembryonic antigen (CEA) have a negative prognostic significance.[14]

Many other prognostic markers have been evaluated retrospectively for patients with colon cancer, though most, including allelic loss of chromosome 18q or thymidylate synthase expression, have not been prospectively validated.[15-24] Microsatellite instability, also associated with HNPCC, has been associated with improved survival independent of tumor stage in a population-based series of 607 patients younger than 50 years with colorectal cancer.[25] 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.[26]

Treatment decisions depend on factors such as physician and patient preferences and the stage of the disease, rather than the age of the patient.[27-29]

Racial differences in overall survival (OS) after adjuvant therapy have been observed, without differences in disease-free survival, suggesting that comorbid conditions play a role in survival outcome in different patient populations.[30]

Follow-up and Survivorship

Limited data and no level 1 evidence are available to guide patients and physicians about surveillance and management of patients after surgical resection and adjuvant therapy. The American Society of Clinical Oncology and the National Comprehensive Cancer Network recommend specific surveillance and follow-up strategies.[31,32]

Following treatment of colon cancer, periodic evaluations may lead to the earlier identification and management of recurrent disease.[33-36] The impact of such monitoring on overall mortality of patients with recurrent colon cancer, however, is limited by the relatively small proportion of patients in whom localized, potentially curable metastases are found. To date, no large-scale randomized trials have documented an OS benefit for standard, postoperative monitoring program.[37-41]

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 the following:[42]

• A CEA level is not a valuable screening test for colorectal cancer because of the large numbers of false-positive and false-negative reports.
• Postoperative CEA testing should be restricted to patients who would be candidates for resection of liver or lung metastases.
• Routine use of CEA levels alone for monitoring response to treatment should not be recommended.

The optimal regimen and frequency of follow-up examinations are not well defined because the impact on patient survival is not clear and the quality of data is poor.[39-41]

Factors Associated with Recurrence

Diet and exercise

No prospective randomized trials have demonstrated an improvement in outcome with a specific diet or exercise regimen; however, cohort studies suggest that diet or exercise regimen may improve outcome. The cohort studies contain multiple opportunities for unintended bias, and caution is needed when using the data from them.

Two prospective observational studies were performed with patients enrolled on the Cancer and Leukemia Group B (CALGB-89803 [NCT00003835] trial), which was an adjuvant chemotherapy trial for patients with stage III colon cancer.[43,44] In this trial, patients in the lowest quintile of the Western dietary pattern compared with those patients in the highest quintile experienced an adjusted hazard ratio (HR) for disease-free survival of 3.25 (95% confidence interval [CI], 2.04–5.19; P < .001) and an OS of 2.32 (95% CI, 1.36–3.96; P < .001). Additionally, findings included that stage III colon cancer patients in the highest quintile of dietary glycemic load experienced an adjusted HR for OS of 1.76 (95% CI, 1.22–2.54; P < .001) compared with those in the lowest quintile. Subsequently, in the Cancer Prevention Study II Nutrition Cohort, among 2,315 participants diagnosed with colorectal cancer, the degree of red and processed meat intake before diagnosis was associated with a higher risk of death (relative risk [RR], 1.29; 95% CI, 1.05–1.59; P = .03), but red meat consumption after diagnosis was not associated with overall mortality.[45][Level of evidence: 3iiA]

A meta-analysis of seven prospective cohort studies evaluating physical activity before and after a diagnosis of colorectal cancer demonstrated that patients who participated in any amount of physical activity before diagnosis had a RR of 0.75 (95% CI, 0.65–0.87; P < .001) for colorectal cancer-specific mortality compared with patients who did not participate in any physical activity.[46] Patients who participated in a high amount of physical activity (vs. a low amount) before diagnosis had a RR of 0.70 (95% CI, 0.56–0.87; P = .002). Patients who participated in any physical activity (compared with no activity) after diagnosis had a RR of 0.74 (95% CI, 0.58–0.95; P = .02) for colorectal cancer-specific mortality. Those who participated in a high amount of physical activity (vs. a low amount) after diagnosis had a RR of 0.65 (95% CI, 0.47–0.92; P = .01).[46][Level of evidence: 3iiB]

Aspirin

A prospective cohort study examined the use of aspirin after a colorectal cancer diagnosis.[47] Regular users of aspirin after a diagnosis of colorectal cancer experienced an HR of colon cancer-specific survival of 0.71 (95% CI, 0.65–0.97) and an OS of 0.79 (95% CI, 0.65–0.97).[47][Level of evidence: 3iiA] One study evaluated 964 patients with rectal or colon cancer from the Nurse’s Health Study and the Health Professional Follow-up Study.[48] Among patients with PI3K-mutant colorectal cancer, regular use of aspirin was associated with an HR for OS of 0.54 (95% CI, 0.31–0.94; P = .01)[48][Level of evidence: 3iiiA]

Source:

https://www.cancer.gov/types/colorectal/hp/colon-treatment-pdq