- Signs and Symptoms
- Causes and Risk factors
- Diagnosis and Testing
- Complications of surgery
Colorectal cancer is a type of cancer, which starts from the lower part of digestive tract that is called large intestine.
Large intestine comprises of caecum, colon (ascending, transverse, descending and sigmoid), rectum and anal canal. Colorectal cancer could initiate in colon or rectum and therefore collectively referred as colorectal cancer.
Main function of large intestine is to absorb excess water and minerals, and maintain bowel motility for excretion of feaces.
In general, cancer can occur in any part of the body. It is a condition in which cells become abnormal and grow out of control. Normal body cells are programmed in our genes to perform specified functions and multiply in control fashion. Hence, old cells die which are replaced by new healthy cells. This is a natural process and keeps repeating during the entire life span.
In cancer patients abnormal cells multiply too fast due to error in their genes and thus outnumber the normal cells of the organ. Cancerous cells initially pile at one place and later can travel to other body parts/ organs causing spread of the disease in the body. Blood and lymph nodes play a vital role in carrying these abnormal cells to other organs.
Cancer is a life-threatening condition; can be proven fatal if not diagnosed at early stage. Many cancer types can be treated adequately if detected early.
Most colorectal cancers starts from rectum while sigmoid and descending colon are found least to be involve in the initiation of cancer.
Majority of colorectal cancers develop from a benign (non-cancerous) mass of cells called polyps.
Untreated polyps over a long period (10-15 years) of time can become cancerous – therefore polyps are referred as precancerous. There are two main types of polyps:
1 Adenomatous Polyps (can become cancerous)
2 Hyperplastic Polyps (usually do not become cancerous)
Colorectal cancer is mostly seen in above people 50 years and is equally found in men and women.
Colorectal cancer is also seen in young age with strong family history or presence of polyps in the person.
Colorectal cancer in Pakistan is seen in patients who have been suffering with chronic ulcerative colitis disease. Distribution of cancer in large intestine is as follows
• Rectum 38%
• Sigmoid colon 21%
• Caecum 12%
• Transverse colon 5.5%
• Ascending colon 5%
• Descending colon 4%
These dysfunctional cells can spread to other organs resulting in spread of cancer to other parts of the body. Liver is the major organ to be affected by spread.
• Patients pass blood mixed with stools, sometimes there is bleeding after passing the stool
• Noticeable change in bowel frequency - more frequent passing of stool, usually loose stool and early morning bloody diarrhea
• Pain and bloating in abdomen, usually after eating food resulting in reduction in diet
• Significant weight loss
• Anemia (due to blood loss) and weakness and tiredness
• Feeling of obstruction in lower abdomen blocking the stool passage.
• There is feeling of not completely emptying the bowel, which is an early and important symptom.
• Presence of non-cancerous polyps in the large intestine is considered as most common cause of colorectal cancer
• Family history of polyps or colorectal cancer increases the risk of developing cancer
• Age above 50 years
• Non-cancerous polyps are seen in young teens sometimes with or without symptoms
• Overweight, excessive alcohol or smoking also contribute to cancer
• Prolonged condition of Ulcerative colitis (Inflammatory bowel disease) can also increase the chance of colorectal cancer
• Diet which is less in fiber or high in red meat or processed meat
• Meat cooked on high temperatures (BBQ, broiling, frying) makes chemicals that enhance cancer development risks
• Conditions such as diabetes mellitus and high cholesterol also contribute in development of cancer
• Similar to most cancers, early detection of pre-cancerous conditions is key for effective treatment and cure
• Periodic screening tests are strongly recommended in people who have family history
• Many screening tests can be used, usually blood tests and colonoscopy (examination of inside of colon and rectum) are carried out
• In suspected patients, the doctor usually perform digital rectal examination which is done by inserting a finger into large intestine to detect any lumps or blood - blood is seen on finger when taken out.
• Colonoscopy and biopsy which are the main test and confirms the diagnosis. A sample of small tissue is taken from affected area of the colon which is visualized under microscope to see the change in size and shape of cells
• Flexible sigmoidoscopy helps in visualizing the sigmoid tube to assess any abnormality
• Barium enema (a liquid) is done inserting a dye through anal passage and multiple images are taken to diagnose cancer.
• CT scan is done to see the spread of cancer
• MRI is done to see local spread
Before proceeding to treatment of any type of cancer, staging is important to see the invasion, spread and depth of cancer. Colorectal cancer tends to involve many other parts of body; liver being the most common which produces more symptoms like jaundice, collection of fluid in abdomen and increase in size of liver.
Cancer is usually spread through blood and lymph nodes. Large intestine has multiple layers of tissues that helps to stage the cancer. Staging is divided into four categories that includes:
Stage I: When cancer is confined to large intestine only
Stage II: When it invades through large intestine wall
Stage III: Lymph nodes get involved
Stage IV: When cancer is spread to other organs
Treatment options are used in accordance to the stage of the cancer.
Commonly used treatment options include: surgery, radiotherapy and chemotherapy
If the colorectal cancer is small and localized in a small area, removal of affected tissues through colonoscopy or laparoscopy (inserting tube by making small holes) may be recommended as less invasive procedure.
Surgery is the most widely used treatment option in invasive colon cancer cases. Some medicines are also used to shrink the cancer before to the surgery
In patients, if surgically possible, the affected area of colon or rectum is removed with adjacent lymph nodes so that after removal there is less chances of re-development of cancer. After removing the affected part, continuity of bowel is maintained by joining other parts of large intestine.
Radiotherapy is also an option here when cancer has spread to other organs. Medicines can be given after surgery to avoid recurrence.
If only rectum is involved two surgeries comes into line one being the anal preserving and another being removing both rectum and anal. In case of rectum, medicines along with radiotherapy (if cancer has spread) are advised as recurrence is low.
- Complications to surgery can either be related to surgery or to any anesthetic problem.
- Bleeding and infection are reported early.
- Injury to anal canal resulting incontinence.
- Injury to any adjacent organ during resecting of cancer.
• Diet should be rich in fiber reducing red meat and meat cooked on high temperature
• Cessation of smoking
• Alcohol withdrawal
• Weight loss
• Life style modifications
• Screening tests in risk population
• Regular use of laxatives Isphaghul to avoid constipation and removal of toxins from large intestine