Colorectal Cancer ​

Anatomy of the Colon and Rectum

The colon and rectum are essential parts of the large intestine. The colon, which makes up most of the large intestine, is a muscular tube that extends about 5 feet in length. It consists of different sections named based on the direction in which food travels through them. The ascending colon begins with the cecum, where undigested food enters the small intestine. It then moves upward on the right side of the abdomen. The transverse colon stretches horizontally from the right to the left side of the body. Descending on the left side, the descending colon leads to the sigmoid colon, which has an “S” shape. The sigmoid colon connects to the rectum, the digestive system’s final part. The rectum stores waste material until it is eliminated through the anus during a bowel movement.

What is Colorectal Cancer, and how does it start?

Colorectal cancer is a disease in which cells in the colon or rectum lining undergo changes and begin to grow uncontrollably, forming a mass known as a tumor. Tumors can be either cancerous (malignant) or noncancerous (benign). Malignant tumors have the ability to invade nearby tissues and spread to other parts of the body. On the other hand, benign tumors can grow but do not possess the ability to spread. It typically takes several years for these cellular changes to progress and develops into colorectal cancer.

What are the symptoms of Colorectal Cancer?

In the initial stages, colorectal cancer often presents without noticeable symptoms. However, if symptoms do arise, they can manifest as:

  • A persistent alteration in bowel habits, such as diarrhea or constipation, or a noticeable change in the consistency of stool
  • A sensation of incomplete bowel evacuation
  • Rectal bleeding or blood in stool
  • Abdominal pain and bloating
  • Persistent feeling of fullness, even after a considerable time since eating
  • Fatigue or tiredness
  • Unexplained weight loss
  • Anaemia

What are the risk factors for Colorectal Cancer?

Factors that can increase the risk of colon cancer include:

  • Tobacco use
  • Alcohol consumption
  • A low-fiber and high-fat diet
  • A diet rich in red and processed meat
  • Lack of physical activity
  • Overweight and obesity
  • A family history of polyps
  • Inflammatory bowel diseases and inherited conditions like Lynch syndrome and familial adenomatous polyposis.

What is screening for Colorectal Cancer, and who needs it?

Screening tests for colorectal cancer are crucial because this type of cancer may not cause symptoms in its early stages. Detecting signs of the disease before symptoms appear can significantly improve the chances of successful treatment. Experts generally recommend initiating screenings at 45 and continuing until at least 75. However, individuals aged 75 and older and those at high risk should consult their healthcare providers to determine the frequency of screenings and the appropriate type of test.
Various screening tests are available, including stool tests and procedures such as colonoscopy and sigmoidoscopy.

How is Colorectal Cancer diagnosed?

Colorectal cancer is diagnosed through several methods to determine if cancer is present and to understand its extent. Here are the common methods used for diagnosing colorectal cancer:

  • Medical History and Physical Examination: The healthcare provider will inquire about your symptoms, medical history, and any family history of cancer. They will also conduct a physical examination, including a digital rectal exam, to check for abnormalities.
  • Blood Tests: Blood tests may assess certain markers associated with colorectal cancer, such as carcinoembryonic antigen (CEA) levels. Elevated CEA levels may indicate the presence of colorectal cancer or monitor its progression.
  • Stool Tests: Stool tests, such as fecal occult blood tests (FOBT) or fecal immunochemical tests (FIT), detect hidden blood in the stool, which could be a sign of colorectal cancer.
  • Colonoscopy: A colonoscopy is considered the most accurate diagnostic procedure for colorectal cancer. It involves using a flexible tube with a camera (colonoscope) to examine the entire colon and rectum. The healthcare provider can also perform a biopsy during the procedure, taking small tissue samples for further analysis.
  • Sigmoidoscopy: Similar to a colonoscopy, sigmoidoscopy uses a flexible tube (sigmoidoscope) to examine the rectum and lower part of the colon.
  • Imaging Tests: Imaging tests, such as CT scans, MRI scans, or PET scans, may be recommended to determine the extent of cancer, identify metastasis, or assess the response to treatment.

What are the stages of Colorectal Cancer?

The stage of cancer indicates the extent of its spread, and it plays a crucial role in determining the appropriate treatment for patients.

  • Stage 0: Also referred to as carcinoma in situ, this is the earliest stage where the cancer is confined to the inner layer of the colon or rectum.
  • Stage 1: Cancer has progressed beyond the inner layer of the colon or rectum but has not spread beyond the wall of the respective organ.
  • Stage 2: Cancer has invaded or penetrated through the wall of the colon or rectum but has not yet reached nearby lymph nodes.
  • Stage 3: Cancer has spread to nearby lymph nodes but has not metastasized to other parts of the body.
  • Stage 4: Cancer has spread to distant sites in the body, such as the liver, lungs, or peritoneum.

What are treatment options for Colorectal Cancer?

The treatment for colorectal cancer depends on various factors, including the stage of cancer, its location, the presence of metastasis, and the individual’s overall health. Treatment plans are usually personalized and may involve a combination of the following approaches:

  • Surgery: Surgery is the primary treatment for localized colorectal cancer. The surgical procedure may involve removing a polyp, a section of the colon or rectum, or the entire colon and rectum (colectomy or proctectomy).
  • Chemotherapy: Chemotherapy uses drugs to kill cancer cells or inhibit their growth. It may be administered before surgery (neoadjuvant chemotherapy) to shrink the tumor, after surgery (adjuvant chemotherapy) to destroy remaining cancer cells, or in advanced cases to control cancer growth and alleviate symptoms.
  • Radiation Therapy: Radiation therapy uses high-energy beams to target and destroy cancer cells. It may be combined with chemotherapy (chemoradiation) before surgery to shrink tumors or eliminate remaining cancer cells after surgery.
  • Targeted Therapy: Targeted therapies are drugs that specifically target specific genes and proteins that help cancer cells survive and grow. These drugs work differently from chemotherapy and may be combined with chemotherapy for advanced or metastatic colorectal cancer.
  • Immunotherapy: Immunotherapy helps the body’s immune system recognize and attack cancer cells.
  • Palliative care focuses on relieving symptoms, managing pain, and improving the quality of life for individuals with advanced or metastatic colorectal cancer.

Treatment plans are usually developed in consultation with a multidisciplinary team of healthcare providers, including surgeons, medical oncologists, radiation oncologists, and other specialists.

Can Colorectal Cancer be prevented?

While colon cancer may not be entirely preventable, there are steps you can take to lower your risk of developing the condition. These include managing risk factors such as avoiding tobacco, limiting alcohol intake, maintaining a healthy weight, following a nutritious diet, and monitoring your family’s medical history. Getting a regular colorectal cancer screening is also essential in high-risk individuals which can help detect it early.

Conclusively, colorectal cancer is a type of cancer that affects the colon or rectum. Detecting it early is crucial for successful treatment. Screening tests are recommended to identify signs of cancer before symptoms appear. Experts suggest starting screenings at age 45 and continuing until age 75. People over 75 or at high risk should consult their healthcare providers regarding screening frequency and tests. Each treatment plan is personalized, and patients should consult a healthcare provider for guidance.

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