Colorectal cancer is one of the most common cancers worldwide, but when diagnosed early, the chance of cure is quite high.
Prof. Dr. Mehmet OZDOGAN
What is Colon and Rectum Cancer?
Colon and rectal cancer is a type of cancer that develops in the large intestine. The colon is the last part of the digestive system where water is absorbed, while the rectum is the last part of the large intestine. When cancer develops in either of these two areas, it is called colorectal cancer.
Colon and rectal cancer usually begins with the uncontrolled proliferation of cells. Most often, this cancer begins with small, benign (non-cancerous) growths called polyps that form on the inner surface of the intestines. Over time, some polyps can turn into cancer. Therefore, regular screening tests for early diagnosis are very important, especially for individuals with risk factors.
Colorectal cancer is one of the most common cancers worldwide, but when diagnosed early, the chance of cure is quite high. It may not cause obvious symptoms in the early stages, but as the cancer progresses, symptoms such as changes in bowel habits, abdominal pain, blood in the stool, and weight loss may occur.
Treatment varies depending on the stage of the cancer, the patient's general health, and how far the cancer has spread. Surgery, chemotherapy, and radiation therapy are common treatment options. Early diagnosis greatly increases the chance of successful treatment and survival.
What are the symptoms of colon and rectum cancer?
Colon and rectal cancer may not usually show any obvious symptoms in its early stages. However, as the cancer progresses, the following symptoms may appear:
- Blood in stool: Red or black blood may be seen in the stool. Red blood usually comes from the rectum, while black blood comes from the upper part of the colon.
- Changes in bowel habits: Unusual changes such as prolonged diarrhea, constipation, or a thinning of the stool size may be observed.
- Abdominal pain or cramping: Discomfort, pain, or cramping in the abdomen may indicate that cancer is growing.
- A feeling that the bowels are not completely empty: You may still feel the need to go to the bathroom even after emptying your bowels.
- Weight loss: Unexplained and unintentional weight loss may indicate cancer.
- Constant fatigue: The cause is unknown constant fatigue, blood loss in the body or cancer may develop.
- Thin stool: Thinner than normal stool may be a sign of a blockage or narrowing in the intestines.
- Bloating or gas: Bloating or excessive gas, especially in the lower abdomen, may be common.
If you have one or more of these symptoms, it is important to see your doctor. However, these symptoms can also be caused by other digestive system problems, so a doctor's examination and appropriate tests are necessary for a correct diagnosis.
How is Colon and Rectum Cancer Diagnosed?
1. Physical Examination and Medical History
The doctor performs the initial examination by listening to the patient's medical history and evaluating their symptoms. They ask if there is a family history of colon or rectal cancer. They also conduct a detailed questioning to learn about rectal bleeding and changes in bowel habits. The doctor may also perform a rectal examination to check for possible abnormalities in the rectum.
2. Colonoscopy
It is the most common and effective method for diagnosing colorectal cancer. Colonoscopy involves a camera placed at the end of a thin, flexible tube to examine the inside of the colon and rectum in detail. During a colonoscopy, the doctor can see polyps or abnormal tissue and take a biopsy. The biopsy is examined in a laboratory to determine if cancer cells are present.
3. Biopsy
If a suspicious polyp or abnormal tissue is detected during a colonoscopy, a biopsy is taken. The biopsy is examined under a microscope to confirm the presence of cancer cells. The type and stage of cancer is determined by the results of this biopsy.
4. Fecal Occult Blood Test (FONT)
This test detects the presence of blood in the stool that is not visible to the naked eye. Blood in the stool can be a sign of cancer or polyps in the colon or rectum. FOBT is used for screening purposes but is not sufficient to make a definitive diagnosis. If the blood is positive, further testing such as a colonoscopy is performed.
5. Barium X-Ray (Barium Enema)
A contrast material called barium is used to image the large intestine and rectum with an x-ray. X-rays are taken after the barium liquid is placed in the intestines. The barium coats the inside of the intestines, allowing tumors or other abnormalities to be seen.
6. CT Colonography (Virtual Colonoscopy)
This method uses computerized tomography (CT) to create a 3D image of the colon. This method is used as an alternative to colonoscopy and can detect tumors or polyps in the colon. However, if any abnormalities are detected, a traditional colonoscopy is required to take a biopsy.
7. Blood Tests
Blood tests are not used to directly diagnose colorectal cancer, but they are done to evaluate the patient's general health. When the cancer is advanced, it can spread to the liver and other organs, so liver function tests may be done. Also, a tumor marker called CEA (carcinoembryonic antigen) may be elevated in some colorectal cancers. CEA levels can be used to monitor the cancer's response to treatment.
How is Colon and Rectum Cancer Treated?
1. Surgical Treatment
It is the most commonly used method in the treatment of colon and rectal cancer. Surgical intervention is especially effective in cases where the cancer is in the early stages. Removal of cancerous tissue is usually the first step.
Polypectomy: This is the process of removing cancerous polyps during a colonoscopy in early-stage colon cancer. When polyps are removed before they become cancerous, complete recovery can be achieved.
Partial colectomy (segmental resection): This is a surgical procedure in which the cancerous section and the surrounding healthy tissue are removed. During this procedure, the removed section of the intestine is usually reattached.
Colostomy or ileostomy: Depending on the location of the cancer, after a section of the intestine is removed, an opening (stoma) can be created in the abdominal wall instead of the anus. This procedure may be necessary, especially in rectal cancer, and may be temporary or permanent.
Laparoscopic surgery: In this less invasive method, surgery is performed through small incisions. This method can help the patient recover faster and experience less pain.
2. Chemotherapy
Chemotherapy is a drug treatment used to kill cancer cells or stop their growth. It is usually used after surgery or if the cancer has spread throughout the body. Chemotherapy can also be used to reduce the risk of cancer recurring.
Adjuvant chemotherapy: Used to reduce the risk of cancer recurring after surgery.
Neoadjuvant chemotherapy: Used to shrink the tumor before surgery. This is especially common in the treatment of rectal cancer.
Palliative chemotherapy: Used to prolong the patient's life and relieve symptoms in advanced stages of cancer.
3. Radiotherapy
Radiotherapy is a treatment method that uses high-energy rays to destroy cancer cells. It is widely used in the treatment of colorectal cancer, especially rectal cancer. It can be used to shrink a tumor before surgery or to destroy any remaining cancer cells after surgery.
External radiation: This is a widely used radiotherapy method. It is usually given with chemotherapy.
Internal radiotherapy (brachytherapy): A small radiation source is placed in an area close to the tumor.
4. Targeted Therapies
Targeted therapies involve drugs that target specific molecules to stop cancer cells from growing. They can be used with or without chemotherapy. These treatments are applied according to the biological characteristics of the cancer and generally have fewer side effects.
Monoclonal antibodies: Bind to cancer cells and stop them from growing. For example, bevacizumab stops the formation of blood vessels leading to the cancer cells, preventing the cancer from growing.
Epidermal growth factor receptor (EGFR) inhibitors: Stop cancer cells from growing. For example, cetuximab and panitumumab are examples of this type of treatment.
5. Immunotherapy
Immunotherapy strengthens the immune system to fight cancer cells. It is often used in advanced cancers and in patients who have not responded to other treatments. Colon cancers that show genetic changes such as MSI-high or microsatellite instability (MSI) may benefit from immunotherapy.
6. Palliative Treatment
In advanced stages of colon and rectal cancer, even if it is not possible to completely remove the cancer, palliative treatment aims to relieve symptoms and improve the patient's quality of life. The aim of this type of treatment is to control symptoms such as pain, intestinal obstruction or bleeding.
