Colorectal Cancer (CRC)

Colorectal cancer (CRC) is a significant health concern, ranking as the second leading cause of cancer-related deaths in the United States. It encompasses cancers of the colon and rectum. The lifetime risk of developing CRC in the US is approximately 1 in 20. In 2016, there were an estimated 134,500 new cases of CRC in the US.

The majority of CRCs arise from neoplastic polyps. Screening methods like fecal occult blood testing (FOBT) and flexible sigmoidoscopy have proven effective in reducing both the incidence and mortality associated with CRC. Colonoscopic removal of these polyps further contributes to reducing CRC incidence and mortality.

Early CRC is often asymptomatic, making screening crucial for detection. When symptoms do appear, they tend to be nonspecific and can vary depending on the tumor's location within the colon. Due to the increasing incidence of CRC in younger populations, recent guidelines advocate initiating screening at age 45 years.

Conservative Treatment

Conservative treatment is not typically applicable for CRC itself, but rather for managing symptoms or complications. This may include dietary modifications or medications to manage bowel changes.

Medications

Chemotherapy is a common treatment for CRC, especially in later stages or after surgery. Neoadjuvant chemoradiotherapy is commonly used for patients with locally advanced rectal cancer. Targeted therapies and immunotherapies may also be used in certain cases.

Surgical Options

Surgical resection is the primary treatment for CRC, aiming to remove the cancerous tumor and surrounding tissue. The type of surgery depends on the location and stage of the cancer. For patients with metastatic disease, palliative resection may be considered to alleviate symptoms like bleeding or obstruction. Solitary hepatic metastases or a small number of lesions localized to one hepatic lobe may also be surgically treated.

Content grounded in authoritative texts, including those listed below.

What is the survival rate for colorectal cancer?
The survival rate depends on the stage of the cancer at diagnosis. The five-year survival rates are approximately 93% for stage I, 74–85% for stage II, 44–83% for stage III, and 8% for stage IV.

How often should I get screened for colorectal cancer?
Screening is appropriate for average-risk individuals aged 50–75 years, although recent guidelines advocate initiating screening at age 45 years. The frequency of screening depends on the method used and your individual risk factors.

What if I have a family history of colorectal cancer?
If you have a family history of CRC in a single first-degree relative, you have a 75–80% increased risk of cancer. Surveillance colonoscopy 10 years earlier than the earliest age of CRC diagnosis in the family or at age 40, whichever comes first should be considered.

In the majority of cases (approximately 75%), no specific underlying cause can be identified for colorectal cancer. These cases are classified as 'sporadic' CRCs, and the individuals affected are considered to be at average risk. However, several factors can increase the risk of developing CRC.

Risk Factors

• Family history: 10–30% of colorectal cancers occur in people with a family history of polyps or CRC.
• Inherited syndromes: About 5% of CRCs are linked to Lynch syndrome, and 1% to familial adenomatous polyposis (FAP).
• Age: The risk of CRC increases with age.
• Personal history of polyps: A history of adenomatous or sessile serrated polyps necessitates periodic colonoscopic surveillance.

• Change in bowel habits: This may include diarrhea, constipation, or a change in the consistency of your stool.
• Rectal bleeding or blood in the stool: This can appear as bright red blood or dark, tarry stools.
• Abdominal discomfort: This may include cramps, gas, or pain.
• Unexplained weight loss: Losing weight without trying can be a sign of CRC.
• Fatigue: Feeling unusually tired or weak.
• Pencil-thin stools: A decrease in the diameter of the stool.
• Iron deficiency anemia: Low iron levels in the blood, which can cause fatigue and weakness.

• Maintain a healthy weight through diet and exercise.
• Eat a diet rich in fruits, vegetables, and whole grains.
• Limit your intake of red and processed meats.
• Avoid smoking and excessive alcohol consumption.
• Undergo regular colorectal cancer screening as recommended by your doctor.

Colonoscopy

A colonoscopy involves inserting a long, flexible tube with a camera attached into the rectum to visualize the entire colon. It allows for the detection and removal of polyps, as well as the collection of tissue samples (biopsies) for further examination.

Fecal Occult Blood Test (FOBT) or Fecal Immunochemical Test (FIT)

These tests detect hidden blood in the stool, which can be a sign of colorectal cancer or polyps. A positive result requires further investigation with a colonoscopy.

Computed Tomography Colonography (CTC)

Also known as a virtual colonoscopy, CTC uses X-rays to create detailed images of the colon. It's less invasive than a traditional colonoscopy but may require a colonoscopy if abnormalities are detected.