Colorectal cancers are cancers that originate from the last part of the digestive system, called the large intestine
. The last 15 cm of the large intestine is called the rectum. Although it is a continuation of the same organ, there is no peritoneum (intra-abdominal membrane) over the rectum area. There are minor differences. Approximately
70% of all colorectal cancers originate from the last 50-60 cm of the intestine.
The frequency of colorectal cancers is due to the spread of Western-style nutrition in our country
Then it gradually increases. T.R. According to the Ministry of Health statistics, it is the third most common cancer in both men,
and women. It is expected that there will be approximately 15 thousand new patients per year. It is rare in young people. Although it can occur at any age, it is most commonly observed after the age of 50. 90% of all patients are over 50 years of age
. The average age of occurrence is around 59-60 years of age.
HOW DOES COLORECTAL CANCER OCCUR?
The formation of colorectal cancer has been researched and revealed in detail
has been placed. Colorectal cancers begin as benign tiny polyps on the inner wall of the intestine.
Polyps gradually grow and become cancerous masses. This whole process develops slowly over 10-15 years
. Then, the growing tumor passes through the intestinal layers and spreads to the body.
Risk factors for colorectal cancer include advanced age, Western-type diet rich in animal fats (burgers, fried foods). such as red meat), smoking, alcohol, polyps, a family history of bowel cancer, genetic syndromes and bowel diseases such as ulcerative colitis or Crohn's disease.
SYMPTOMS
Symptoms in colorectal cancer may vary depending on the location and extent of the tumor
. They usually do not cause symptoms in the early stages. As the tumor mass grows,
it may cause obstruction or perforation in the intestine, or it may adhere to surrounding tissues, causing pain
and disruption of bowel movements.
Tumors located in the right colon may cause symptoms later. data rler. The right colon is wider, so symptoms such as obstruction are usually not observed. Patients usually consult a doctor with complaints such as hidden blood loss, severe anemia, weakness and shortness of breath. There may be changes in bowel habits, attacks of constipation and diarrhea
defecation, spasm-like abdominal pain, abdominal bloating and weight loss.
These attacks may be accompanied by nausea and vomiting.
In left colon and rectum cancers, blood in the stool is the most common finding. Again, changes in bowel habits, constipation, incomplete emptying after going to the toilet, and abdominal pain/swelling may occur. Most patients undergo colonoscopy during routine screening without any symptoms. It should not be forgotten that they are diagnosed with
.
HOW ARE COLORECTAL CANCERS DIAGNOSED?
Colonoscopy without delay in individuals with symptoms of colorectal cancer
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must be done. Definitive diagnosis can only be made by visualizing the tumor during colonoscopy and detecting cancer cells with pathology in a visual biopsy.
After diagnosis, ultrasonography is used to determine whether the tumor is widespread.
At least one or more of the following computed tomography (CT), magnetic resonance imaging (MRI) or PET tomography
exams should be performed.
Colorectal Cancer Staging
Exact staging of colorectal cancers is done after surgery. American Joint
According to the Committee on Cancer (AJCC) TNM staging system, there are a total of 4 stages.
In Stage 1, the tumor is small, the innermost mucosa and/or muscle of the intestinal wall. It retained the /p>
layers. Stage 2 tumors have now reached or passed through the outermost layer of the intestine, called the serosa. Stage 3 tumors have now spread to the lymph nodes around the intestine. Stage 4 cancer means cancer that has spread to other organs of the body at an advanced stage. They most commonly metastasize to the liver, peritoneum and lungs
.
WHAT GENETIC TESTS SHOULD BE PERFORMED IN COLORECTAL CANCER?
Extensive stage in colorectal cancer. Genetic testing is routinely used to determine treatment in patients p>
It is done for the purpose of guiding. It is not necessary to perform a genetic test other than microsatellite instability in early stage patients.
In advanced stage patients, RAS mutation and BRAF mutation should be checked. Treatment can be given in different ways depending on whether there is a mutation in the RAS
gene. RAS
mutations are seen in 40% of all prevalent stage patients. BRAF mutation
It is seen in approximately 10% of patients and is a sign of a poor outcome. Before treatment planning
it should be determined whether there is RAS and BRAF mutation and the treatment should be planned according to these
results.
TREATMENT
Surgery and chemotherapy are the most commonly used treatment methods in the treatment of colorectal cancer
. The treatment prescribed varies depending on where the tumor is located in the intestine
and its extent.
The main treatment of colorectal cancer expected to result in cure in early stage patients is surgical resection. In order for surgery to be performed, it must be shown that the cancer has not spread throughout the body. Surgery has no place in common disease, with exceptions. During the surgery, the tumor is removed, leaving intact intestinal tissue around it. In a good surgery, at least 14
lymph nodes should be removed together with the tumor. Staging of colorectal cancer is done by surgery
. In cases where a missing lymph node is detected, other treatment options are used more frequently, considering that the tumor may be more widespread due to incomplete staging.
Rectal cancer surgery is a more specialized surgery. Not every surgeon can perform rectal cancer surgery; it requires special knowledge and experience. A technique called total mesorectal
excision should be applied to ensure normal defecation, especially in tumors close to the lower end of the rectum. In tumors located at the very tip, it may be necessary to close the anus to completely remove the tumor. In this case, the end of the intestine is attached to the abdominal wall and a colostomy is opened. The important thing is to remove the tumor completely
.
In some patients whose tumor is completely removed, preventive
chemotherapy may need to be given depending on the risk of recurrence. cancer drugs blood circulation They reduce the possibility of recurrence by passing into the blood circulation and killing cancer cells that we cannot see in the body. Cancer drugs
Although they are usually given intravenously, some drugs can be given orally as pills. It is essential to give preventive chemotherapy in stage 3 patients. While it is required in some stage 2 patients
, there is no need for preventive chemotherapy
since the recurrence risk of stage 1 patients is already low.
According to the performance status of colorectal cancer patients with widespread disease
They need to receive chemotherapy. Although full recovery is generally not possible in these patients, they can have a long and quality life. For this purpose, different combinations of drugs called 5-fluorouracil,
oxaliplatin and irinotecan are used.
New generation biological drugs, generally known as target-oriented smart molecules, are also included in the treatment.
is added. For this purpose, antiangiogenic drugs such as bevacizumab, which regulate the vascular structure of the tumor and prevent the blood supply to the tumor, are frequently used.
In patients with RAS wild type, anti-EGFR drugs (cetuximab and panitumumab) are the first choice
They are increasingly preferred in stepwise treatment.
Radiotherapy is used only in certain stages of rectal cancer.
Radiotherapy is used for the purpose of making the surgeon's job easier by shrinking the tumor before surgery
or It can be given together with chemotherapy to prevent postoperative recurrences
.
SCREENING AND FOLLOW-UP IN COLORECTAL CANCERS
Colorectal cancers are cancers in which deaths can be prevented by screening. It comes after breast
and cervical cancer. Since the tumor does not cause symptoms before it reaches very large sizes, screening is essential. The process of colorectal cancer formation begins as benign polyps. For this reason, when polyps detected during screening colonoscopy are removed before they become cancerous, cancer formation is prevented.
Screening for colorectal cancer should start after the age of 50. Screening should start at earlier ages in individuals at risk as mentioned above. Tests used in early diagnosis
stool occult blood test, sigmoidoscopy (end 1/3 of the intestine) or
colonoscopy. T.R. According to the National Cancer Screening Program carried out by the Ministry of Health, it is recommended to perform a fecal occult blood test every 2 years between the ages of 50 and 70, and a colonoscopy twice at the ages of 51 and 61
.
However, in patients with bleeding in the stool, constipation or other signs and symptoms, these tests should be performed immediately without wasting time. People who have polyps at risk of turning into cancer
detected and removed should be evaluated again with colonoscopy 1-3 years after the first examination.
Follow-up of patients diagnosed with cancer and treated should be multidisciplinary. It should be done in accordance with the standards set by a team
.
HOW CAN WE PROTECT FROM COLORECTAL CANCER?
There are many things that can be done to reduce the risk of colorectal cancer. Nutrition plays an important role in protecting against colon cancer. It is recommended to consume high-fiber, low-fat foods and stay away from red meat, fried foods, fast food products such as hamburgers, etc. as much as possible. Additionally, physical exercise,
losing excess weight, and avoiding smoking and alcohol reduce the risk of colorectal cancer.
However, the most important thing that can be done for protection is to participate in screening programs
and have a colonoscopy after the age of 50.
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