Colorectal cancers are seen at variable incidences in different populations and more commonly in industrialized societies compared to developing countries. The incidence of colon cancer is the same in men and women, and it is the third most common cancer among all cancers.

WHAT ARE THE RISK FACTORS?

Geography: The distribution of the disease varies between regions in the world. While it is more common in North America and New Zealand, it is less common in Africa and Central America.

Being over 50 years of age: The likelihood of developing colorectal cancers increases with age. The majority of patients are over 50 years of age.

Adenomatous polyp history: The risk of cancer increases when there are adenomatous polyps in the large intestine.

Inflammatory bowel diseases: Presence of inflammatory bowel diseases such as Crohn’s disease and especially ulcerative colitis increases the risk of developing colorectal cancers.

Genetic changes: The presence of genetic syndromes in the family increases the risk of colon cancer. Non-hereditary colon cancer (HNPPC-hereditary nonpolyposis colorectal cancer-Lynch syndrome) and familial adenomatous polyposis (familial adenomatous polyposis) increase the risk of developing colon cancer. When these patients are left untreated, they develop colon cancer until the age of 40.

The presence of colon cancer in the family: The presence of colon cancer in first-degree relatives increases the risk of developing colon cancer. The risk increases significantly in individuals with more than one family member.

The risk of developing colorectal cancer is doubled in breast, ovarian, and uterine cancers.

Low-fiber and high-fat diet, a sedentary lifestyle, diabetes, obesity, smoking and use of tobacco products, alcohol consumption, and exposure to radiation therapy may increase the risk of developing colon cancer.

WHAT ARE THE PRESENTING COMPLAINTS OF COLORECTAL CANCER PATIENTS?

Although the complaints may vary depending on the location of cancer, the patients may present with a variety of symptoms including blood in stool, changes in bowel habits, diarrhea and constipation, feeling of incomplete defecation, frequent defecation, reduction in the stool caliber, anal discharge other than defecation, abdominal pain, cramps, bloating, unexplained weight loss, weakness, and fatigue.

HOW IS THE DIAGNOSIS MADE IN COLORECTAL CANCERS?

Diagnosis is made based on the findings obtained from the anamnesis, physical examination, and diagnostic tests. The patient’s complaints are evaluated in the first place by obtaining the anamnesis. Especially family history, bleeding, and defecation habits should be questioned. After a detailed physical examination, the physician should palpate the anorectal area by his/her fingers (rectal touch).Rectal touch allows examining a 7-8 cm portion of the rectum.

After these procedures; the first diagnostic test is colonoscopy, in which your large intestine is evaluated with a telescopic camera. In case of doubt, a biopsy may be performed.

When the biopsy results are affirmative for cancer, the extent of the spread of the disease should be determined (staging) before a treatment plan can be made. The ultrasound probe used in endorectal ultrasonography allows understanding how deep the tumors are located in the rectum and to what extent the disease has spread to lymph nodes and the surrounding tissue. Computed tomography or MRI provides information about the spread of colon cancer to distant organs (liver, lung, etc.).

HOW IS COLON CANCER TREATED?

Despite all advances in adjunctive treatment methods including chemotherapy and radiotherapy, the main treatment of colon cancer is surgery. The main purpose of the treatment is to perform a wide excision of the cancerous region including the regional lymph nodes. The first-line treatment of the stage I, II, and III colon cancers is surgery, while it is chemotherapy in the fourth stage. In rectum cancer, the first-line treatment is surgery for the stage-I disease. In the stage II and III disease, neoadjuvant therapy (preoperative radiotherapy or adjuvant chemotherapy) is the first-line treatment. Surgery is performed afterward. The surgical technique varies depending on the site of the tumor. While the right half of the large intestine (colon) is removed for the treatment of right-sided tumors, the left half of the colon is removed in the left-side ones. After the removal, the ends of the colon are connected appropriately. In advanced-stage colon cancers (in the presence of liver and intra-abdominal membrane metastases, etc.), surgery may involve removal of the metastatic organ or hot chemotherapy can be applied. In rectal cancer, the rectum is divided into three according to the region where cancer is located. In tumors of the middle and lower rectum, a temporary ileostomy (diversion of the intestine out of the abdomen) is performed following the removal of the cancerous area. An ileostomy may not always be necessary for upper rectal cancers. Permanent colostomy should be performed for lower rectal tumors if the anal muscles are involved. In recent years, sphincter sparing operations have been started to be performed in patients after neoadjuvant treatment when muscles are not involved and the disease has not spread to lymph nodes. In early-stage (T1) rectal cancers, local excisional surgery in the anal region or TEM (transanal endoscopic microsurgery) can be performed.

With the advances in laparoscopic surgery techniques and instruments, laparoscopic surgery is successfully performed in malignancies besides the treatment of benign diseases by laparoscopy.

Chemotherapy for colon cancer is usually performed postoperatively if the cancer has spread to lymph nodes (stage III). This reduces the risk of recurrence of cancer in the future. Outcomes of chemotherapy in stage II colon cancers have not been established, yet. Radiotherapy is used less frequently in early-stage colon cancers. However; it is often used in the treatment of rectal cancer, especially when cancer cells have invaded the rectum wall or spread to nearby lymph nodes. After surgery, radiation therapy to the surrounding area around the rectal cancer is often performed in combination with chemotherapy to prevent recurrence of the disease.

Colorectal cancers have the best prognosis among the digestive system cancers. Although cancer prognosis worldwide has been established based on survival for the following 5 years after cancer, most patients live for more than 5 years. The 5-year survival rates for colorectal cancer are 90-100% in stage 1 disease, 60-85% in stage 2 disease, 50-80% in stage 3 disease, and 10% in stage 4 disease.