Wednesday, November 9, 2022

Colorectal (large intestine) cancer

Colorectal (large intestine) cancer


Our digestive system digests food and absorbs nutrients from it. Esophagus (food pipe), stomach (stomach), small intestine and large intestine together make up the digestive system. The large intestine begins with the colon, which is about 5 feet long and ends at the rectum and anus.

The walls of the colon and rectum have four layers of tissue. Cancer occurs when cells in the body begin to grow uncontrollably. Colorectal cancer begins in the innermost layer of the colon wall. Most colorectal cancers begin with small polyps. These polyps are a group of cells. Over time, some of these polyps develop into cancer. This cancer first spreads in the wall of the large intestine, then in the surrounding lymph nodes and then in the whole body.

Not all polyps develop into cancer. The likelihood of a polyp developing into cancer depends on the type, size, and number of polyps.

There are two types of polyps:

Adenomatous polyps (adenomas): These can develop into cancer.

Hyperplastic and inflammatory polyps: These do not usually develop into cancer.

Colorectal cancer is curable if detected on time and treated appropriately.

Colon cancer and rectal cancer are very similar and are discussed together under the name of colorectal cancer. But the rectum is in a narrow space called the pelvis. Here it is attached to the surrounding organs and pelvic bones. Because of this, rectal cancer screening and diagnosis methods are slightly different.

Most of these cancers are adenocarcinomas. Neuroendocrine (carcinoid) tumors, gastrointestinal stromal tumors, lymphomas, and sarcomas can also occur in the colon, but are rare.

Some facts about colorectal cancer:

Colorectal cancer is the third most common cancer worldwide.

It occurs globally in 1.8 million people each year.

It causes 862,000 deaths per year globally.

The lifetime risk of developing colorectal cancer is one in 20.

Colorectal cancer causes and risk factors (RISK FACTORS)

Sometimes the DNA of a healthy cell changes during cell division. This causes the cells to grow uncontrollably and become cancer.

Anything that increases someone's risk of developing cancer is called a risk factor. Risk factors do not cause disease, they only increase the risk.

Risk factors for colorectal cancer include:

old age

Western diet (high-fat diet, high in red meat and processed meat; low-fiber diet)

History of colorectal polyps (adenomatous polyps, large polyps and multiple polyps)

Family history of colorectal cancer (one-third of colorectal cancer patients have family members with the disease)

Past history of colorectal cancer (if you have previously been treated for colorectal cancer)

inflammatory bowel disease of the colon; Ulcerative colitis and Crohn's disease (risk of cancer increases with duration and severity)



Physical inactivity

Smoking and alcohol consumption

Genetic risk factors (hereditary characteristics) - GENETIC RISK FACTORS

A small percentage (about 5%) of colorectal cancer patients have gene changes that are inherited and increase the risk.

Common hereditary colon cancer syndromes are:

Hereditary nonpolyposis colorectal cancer (HNPCC): HNPCC, also called Lynch syndrome, increases the risk of colon cancer and some other cancers. People with HNPCC develop colorectal cancer before the age of 50.

Familial adenomatous polyposis (FAP): FAP is a rare disease that causes thousands of polyps to form in the large intestine. People with FAP have an increased risk of developing colorectal cancer before the age of 40.

Symptoms of Colorectal Cancer

Like other stomach cancers, colorectal cancer usually has no symptoms in its early stages.

Symptoms of colorectal cancer include:

changes in bowel habits; Persistent diarrhea, constipation, or the feeling that the stomach is not completely empty

Feeling constantly weak or tired and not having an appetite

lose weight

Decrease in hemoglobin (anemia)

Stomach pain or discomfort

Red or black blood spots in the stool

Note that many of these symptoms can occur in diseases other than colorectal cancer.

Colorectal cancer diagnosis

Health Examination: Understanding the symptoms and checking the signs by a doctor is essential to diagnose the disease.

Faecal Occult Blood Test (FOBT): Tumors cause small amounts of bleeding that are not visible to the naked eye. This is determined by the in test.

There are two types of this test:

Guaiac FOBT

Faecal Immunochemical Test (FIT) - This is a new and improved test.


Colorectal cancer is confirmed by colonoscopy.

A colonoscope is a flexible thin tube with a camera inside. It transmits images of the inside of your colon to a monitor. If an abnormality is found, a small sample is also taken from it, which is called a biopsy.

Virtual colonoscopy

A special type of CT scan is used to examine the colon. It is also called colonography.


Biopsy means taking a small sample of a tumor and examining it under a microscope. This is done by a pathologist. Gene testing can also be done on biopsy samples if needed.


Cancer cells come out of the tumor and spread in the body in three ways; (1) through the blood (2) through the lymphatics (3) directly into the surrounding tissues.

Staging is determining the spread of the disease. After colon cancer is diagnosed, we do tests to find out how far the tumor has spread. For this we do some of the following tests.

Blood test: Different types of elements are checked in the blood. Some patients have anemia (low hemoglobin). Apart from this, liver and kidney tests are also done.

Tumor marker: Most colorectal cancers produce a substance called CEA (carcinoembryonic antigen). A blood test checks its levels in the blood. It is a useful test for monitoring cancer after treatment.

Computed Tomography (CT) Scan: In this test, the patient is placed in a CT scanner. X-rays then take images of the internal organs from all sides. Computers develop these images and give us precise information about the internal situation. By injecting contrast we get a better image.

Magnetic Resonance Imaging (MRI): Instead of X-rays, this test uses radio waves, and powerful magnetic fields. It is widely used in the staging of rectal cancer.

Positron emission tomography (PET) scan: Cancer cells take up too much glucose. In this test, radioactive glucose (18F-fluorodeoxy; FDG) is injected. This radioactive glucose goes into the tumor which we can see with the scanner.

These tests help us provide a stage of the cancer. Broadly we classify cancer into three categories:

Localized - The cancer is confined to the organ in which it started.

Local spread - the cancer has spread to nearby lymph nodes or has spread beyond the walls of the organ in which it started.

Distant spread - Cancer has spread to distant organs, away from the organ of origin of the tumor. This is called metastasis.

TNM (Tumor, Node and Metastasis) classification

This classification was developed by the American Joint Committee on Cancer (AJCC). It is used to accurately classify the stage of cancer. It is based on the following three main elements and ranges from Stage I to IV.

Tumor size (T): How far into the layers of the colon has the cancer spread? Has the cancer spread to nearby structures or organs?

Spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes? And how many lymph nodes?

Metastasis (M): Has the cancer spread to distant lymph nodes or distant organs such as the liver or lungs?

T, N and M are followed by numbers and letters that give more details. The higher the number, the more advanced the cancer. By combining information from T, N and M we provide a stage of cancer. Colorectal cancer ranges from stages I to IV.

Stages I to III are localized disease and stage IV is cancer that has spread (metastatic disease).

The chances of recovering from cancer depend on the stage of the cancer at the time of treatment. The fewer the steps the better the chances.


Treatment of localized (limited) disease - surgery

Colon cancer treatment depends on the stage and location of the tumor.

The primary treatment for early-stage colorectal cancer is surgery.

In this, the cancerous part of the large intestine is removed along with the surrounding lymph nodes. Then the cut parts of the intestine are joined together to re-establish the continuity of the intestine (anastomosis).

Sometimes, when the tissue is not healthy, the anastomosis is unlikely to close. In such cases, the intestine is opened above the abdomen called an ostomy (ileostomy or colostomy). It is temporary and is discontinued after improvement of the patient's condition and chemotherapy (if necessary).

Surgery for Colon Cancer - Colectomy (COLECTOMY)

Partial colectomy, hemicolectomy or segmental resection

Colon cancer surgery is generally called partial colectomy. This surgical procedure has different names depending on the part of the colon that is removed; Right hemicolectomy, left hemicolectomy, sigmoidectomy, transverse colectomy, right or left extended hemicolectomy and anterior resection.

Treatment of rectal cancer

Chemotherapy, radiotherapy and surgery are combined to achieve the best results in enlarged rectal tumors, which is called multimodal treatment. At present, in the treatment of rectal cancer, chemotherapy or chemoradiotherapy is given first, which is called neoadjuvant (neoadjuvant) treatment, after which surgery is done.

In rectal cancer surgery, the cancerous part of the rectum is surgically removed along with the surrounding lymph nodes along with the healthy tissue. The surgical procedure is known by different names depending on the part of the rectum that is removed; Anterior resection, low anterior resection, ultra-low anterior resection or abdominoperineal resection.

The cut sections of the intestine are either joined together to re-establish the continuity of the intestine (anastomosis) or the intestine is opened above the abdomen, which is called a colostomy.

An important information needed before surgery is how close the tumor is to the anus. The decision to perform a colostomy or not depends on the distance of the anus from the tumor and the entrapment.

Total colectomy or subtotal colectomy

Sometimes, the entire colon is removed. This is done in patients whose remaining part of the colon is also affected by polyps, inflammatory bowel disease or intestinal obstruction.

There are two ways to operate for colorectal cancer;

Open, etc


In open surgery, a long incision is made in the abdomen.

Laparoscopic surgery is a special technique of operating, also known as key-hole surgery, minimally invasive surgery or minimal access surgery. In this, instead of a large incision, the operation is performed by inserting special instruments and a camera through small holes on your abdomen. These devices are made thin and long with special construction. The camera projects high-resolution images of the inside of your abdomen onto a large screen, which allows the surgeon to operate inside the abdomen. This technique is one of the most important innovations in the surgical field in the last few decades which has revolutionized the field of abdominal surgery. This surgical technique is now available and valid for most abdominal operations. The use of this technique is also beneficial in the operation of stomach cancer.

Benefits of laparoscopic surgery

Open abdominal surgery requires a large incision and due to this, it takes time to recover and a long stay in the hospital. Minimally invasive surgery means "less pain", "minimum scars" and "quick recovery". Shorter stays in ICU and hospital. Because of the larger view of the inside of the abdomen on a large monitor, blood loss during surgery is reduced. You can quickly start walking and feeding by mouth. Compared to open surgery, the risk of infection and hernia is also less.

Cancer will sometimes block the colon. In such cases, a stent can be placed to remove the blockage, improve the patient's condition and then perform surgery. If a stent cannot be placed or is not available, then surgery is performed directly. In such cases, usually, the ends of the intestine are not reattached, but brought out as an ostomy. When the patient's health improves, the ends of the intestine are later reattached in a second operation.

Treatment of advanced cancer

Surgery - Curative

Some stage IV cancers are confined to a few locations in the lungs, liver, and peritoneum. If all these spots of colon and cancer can be safely removed by surgery, then an attempt can be made to treat the cancer by surgery.

resection of the liver

This is a surgical procedure to remove the cancerous part of the liver, also called hepatectomy or metastasectomy.

lung resection

Lung resection is a surgical procedure to remove the part of the lung that contains cancer.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC)

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) treats colorectal cancer that is confined to the abdominal peritoneum. During cytoreductive surgery, all visible tumor is surgically removed, and only microscopic cancer cells are spared. The aim of HIPEC is to destroy the remaining microscopic cancer cells. In HIPEC, a concentrated and heated chemotherapy solution is given directly into the stomach to kill those cells.

This approach helps patients live longer and gives them a chance to stay cancer-free for longer. We give chemotherapy, radiotherapy or both before surgery in these patients.


Cancer that has spread to a few places in the liver is treated with embolization or ablation.


Embolization means cutting off the tumor's blood supply. A thin catheter is inserted into the blood supply vein of the tumor and blocked by small particles and other agents. Chemotherapeutic agents and radioactive beads can also be delivered directly to the tumor during this time, which is called chemoembolization or radioembolization.


Ablation uses extreme heat, cold or chemicals to kill tumor cells. It is good for small tumors that are smaller than 2 centimeters. Radiofrequency ablation (RFA) uses high-frequency radio waves to generate heat and kill the tumor. A needle is inserted into the tumor as seen in ultrasound or CT scan. Microwave ablation uses microwaves to generate heat and kill the tumor. Cryoablation, or cryotherapy, involves inserting a metal needle into the tumor and freezing it to death. Tumor cells can also be killed by percutaneous ethanol injection (PEI).

Surgery - palliative

An ostomy (ileostomy or colostomy) is an operation to make an opening in the intestine and bring it out through a hole in the abdominal wall. A bag is well placed over it in which the feces are excreted. An ostomy is performed when the tumor has grown and is blocking the intestines, the patient is unfit to undergo major surgery to remove the tumor, or the cancer has spread to other parts of the body.


Chemotherapy uses drugs to destroy cancer cells. Many medicines are given together for better results. These are given in a specific order on specific days as a cycle.

Adjuvant chemo - In patients with localized colon cancer, chemotherapy is usually given after surgery. It destroys those cells that remain in the body even after the operation. The decision to give chemotherapy depends on the surgical stage. It is usually given when the cancer has spread to the lymph nodes or moved to the outer layers of the intestine. In this way, chemotherapy helps reduce the risk of cancer recurrence and death from cancer.

Neoadjuvant chemo - If the tumor has grown excessively, chemotherapy is given before surgery. This will shrink the cancer and give better results from the subsequent operation.

Palliative chemo - Chemotherapy in metastatic (spread) cancer prolongs life and improves its quality.

Targeted therapy

Substances that identify and target cancer cells without harming normal cells.

Monoclonal antibodies

They are made up of the same type of immune cells.

Vascular Endothelial Growth Factor (VEGF) Inhibitors: VEGF causes tumors to grow and new blood vessels to form. VEGF inhibitors block this pathway.

Epidermal growth factor receptor (EGFR) inhibitors: EGFRs are proteins on the surface of cancer cells that help them grow. EGFR inhibitors block these proteins and stop cancer cells from growing.

Kinase inhibitors: Human cells contain many different kinases, and they help control important functions. Kinase inhibitors block these enzymes and prevent cancer cells from growing.


It uses the patient's immune system to fight cancer. Immune checkpoint inhibitor therapy is a type of immunotherapy.


Radiation therapy uses high-energy X-rays to destroy cancer cells.


Survival rates

The probability of survival after cancer treatment is measured in 5-year survival rates. It indicates the chances of getting rid of cancer and surviving after treatment. Survival rate depends on the type and stage of the cancer. After treatment for stage 1 colorectal cancer, the 5-year survival rate is slightly more than 90%. For stage 2 it is around 60-90%. For stage III colorectal cancer, the 5-year survival is 45 to 90% and for stage 4, the 5-year survival is about 15%.

Screening for colon cancer

If we can detect diseases in time, we can treat them better.

Screening can detect diseases in those who are outwardly healthy and who have no symptoms of disease.

It takes 10-15 years for an abnormal cell to develop into colorectal cancer. We can also remove them at the stage of a polyp and prevent cancer. Even if they turn into cancer, we can identify them at an early stage, and better survival is possible.

However, not everyone needs screening. Screening is done in people who have a higher than normal risk of developing colorectal cancer.

Screening tests for colorectal cancer include colonoscopy, CT colonography, sigmoidoscopy, and stool tests.

Who should be screened for colorectal cancer?

If your age is more than 45 years

If you have a family history of colorectal cancer or polyps

If you have had colorectal cancer or polyps before

If you suffer from inflammatory bowel disease (ulcerative colitis or Crohn's disease).

If you have a family history of hereditary colorectal cancer syndromes such as familial adenomatous polyposis (FAP) or Lynch syndrome (HNPCC)

If you have a history of radiotherapy to the stomach (abdominal) or pelvic area to treat cancer

How to reduce the risk of colorectal cancer?

We can classify colorectal cancer risk factors into modifiable and non-modifiable. Age and genetic factors are non-changeable and we cannot do anything about it.

But we can reduce the risk by avoiding those risk factors that we can control.

We can reduce our risk by taking the following steps:

Keep your weight under control

Do regular physical activity and exercise

Eat a healthy diet that is especially rich in fibrous fruits, vegetables, and whole grains, while avoiding processed foods.

Avoid smoking and tobacco

Do not consume alcohol

Be alert! Stay healthy!

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