Colon - Rectal Cancer

21.03.2024

COLON AND RECTUM CANCER DIAGNOSIS AND TREATMENT

Colorectal cancer is defined as cancer of the large intestine (colon) and rectum (rectal) and is one of the most common types of cancer worldwide. This type of cancer is usually caused by abnormal changes in intestinal cells. These cells can multiply uncontrollably and form cancerous tumors. The importance of colorectal cancer is that it is highly treatable when detected at an early stage. That's why regular screenings and early diagnosis are vital. Risk factors include advanced age, family history of colorectal cancer, inflammatory bowel diseases, some genetic syndromes, diabetes and obesity. Dietary habits and lifestyle can also affect risk. Colorectal cancer, especially in the early stages, may not show obvious symptoms, but symptoms such as bleeding, abdominal pain, weight loss and changed bowel habits can be observed. Measures such as a healthy diet, regular exercise and limiting alcohol consumption can be effective in preventing this type of cancer. Early diagnosis and treatment significantly increases rates of complete recovery from the disease.

WHAT ARE THE RISK FACTORS?

There are a number of factors that can increase the risk of colorectal cancer. These risk factors may vary from individual to individual, and it is usually a disease that occurs as a result of more than one factor coming together. Some important factors that may increase the risk of colorectal cancer:

Age: Age increases the risk of colorectal cancer. This type of cancer is generally more common in individuals over the age of 50.

Family History: Family history may increase the risk of people with family members who have a history of colorectal cancer. People with a history of colorectal cancer, especially in first-degree relatives (parents, siblings, children), are at higher risk.

Personal Story: Having previous bowel problems such as colorectal cancer, polyps, or inflammatory bowel disease (for example, ulcerative colitis or Crohn's disease) may increase personal risk.

Genetic Factors: Some genetic syndromes may increase the risk of colorectal cancer. In particular, genetic syndromes such as Lynch syndrome and familial adenomatous polyposis (FAP) may increase the risk of colorectal cancer.

Diabetes: It is thought that diabetic patients have an increased risk of colorectal cancer.

Nutrition habits: High-fat, low-fiber eating habits may increase the risk of colorectal cancer. At the same time, consumption of red meat and processed meat may also increase the risk.

Physical Activity: Lack of regular physical activity may increase the risk of colorectal cancer.

Alcohol and Smoking: Alcohol consumption and smoking may increase the risk of colorectal cancer.

Weight: Obesity or being overweight may increase the risk of colorectal cancer.

Inflammation: Chronic bowel inflammation or inflammatory bowel diseases may increase the risk of colorectal cancer.

People with these risk factors are recommended to be more careful and follow regular screening tests. To minimize risk factors, healthy lifestyle changes, regular exercise, a healthy diet and following medical recommendations should be followed. It is also important to identify personal risk factors, such as family history or genetic factors, and talk about them with your doctor.

Image 1: Many risk factors have been identified in the development of colon cancer. With colon cancer and screening, the chance of early diagnosis and complete recovery increases.

HOW DOES IT OCCUR?

The development mechanisms of colorectal cancer are complex and occur as a result of the interaction of multiple factors. Genetic mutations or changes usually occur in normal intestinal cells initially. These mutations cause intestinal cells to lose normal control of growth and division. Small abnormal tumors called polyps form as a result of these mutations, and over time, some polyps can turn into cancer. It is known that many factors such as genetic factors, family history, age, nutritional habits and environmental factors play a role in the development of colorectal cancer. With the combination of these factors, normal intestinal cells turn into cancerous cells and tumors begin to grow.

WHAT ARE THE SYMPTOMS?

Signs and symptoms of colorectal cancer may vary from person to person, but some common symptoms include:

Bleeding: Bright red or dark blood in the stool.

Change in Defecation Habits: Diarrhea, constipation, or other changes in bowel habits, especially if these changes persist for several days or longer.

Change in Stool: Stools appear narrower or different.

Abdominal Pain and Discomfort: Cramping, gas or pain in the abdomen.

Weight Loss: Unexplained weight loss.

Fatigue and Weakness: Persistent fatigue or symptoms of anemia.

Loss of appetite: Unexplained loss of appetite.

Feeling of Discomfort: Feeling of not being able to defecate completely.

Each of these symptoms may not be specific to colorectal cancer and may be triggered by other health conditions. However, the presence of any such symptoms should be evaluated by a doctor, especially in individuals over the age of 50 or those with a family history of colorectal cancer. Early diagnosis is very important for the treatability of colorectal cancer.

HOW IS IT DIAGNOSED?

Several different medical tests and procedures are used to diagnose colorectal cancer. The first step is to take the patient's medical history and perform a physical examination. Next, doctors may perform colorectal cancer screening tests. These screening tests may include fecal occult blood testing (FOBT), fecal DNA testing (FIT-DNA), sigmoidoscopy, colonoscopy, and computed tomography colonography (CT colonography). If there are positive results or symptoms, a biopsy is performed for further evaluation. This allows cancer to be diagnosed by taking tissue samples and pathological examination. Imaging tests (for example, CT scans or MRI) may also be used to evaluate whether the cancer has spread. When colorectal cancer is diagnosed, the patient's treatment plan is created and appropriate treatment methods are selected, taking into account the stage of the cancer and other factors.

Image 2: For diagnosis of colon cancer, a colonoscopy and a biopsy of the mass are required.

WHAT ARE THE PATHOLOGICAL TYPES?

Colorectal cancer is a type of cancer that starts on the inner surface of the large intestine (colon) or rectum (last part of the anus). Pathological types of colorectal cancer may differ depending on the cellular characteristics of the tumor and how it spreads into tissues. These types can be:

Adenocarcinoma: It is the most common type of colorectal cancer. In this type of cancer, a tumor originates from the gland cells lining the inner surface of the colon or rectum. Adenocarcinoma accounts for the majority of all colorectal cancer cases.

Mucosal Cancer: This type of cancer arises from cells on the mucosal surface. The mucosal surface covers the inner surface of the colon and rectum.

Squamous Cell Carcinoma: This type of cancer arises from squamous cells and can develop in the squamous cell part of the rectum. This type of colorectal cancer is less diagnosed.

Adenosquamous Carcinoma: This type of cancer is a rare type that combines features of adenocarcinoma and squamous cell carcinoma.

Lymphoma: Colorectal lymphoma is a type of cancer that arises from immune system cells and rarely occurs in the colon or rectum.

Sarcoma: Colorectal sarcoma is a type of cancer that arises from the muscle or connective tissues of the intestines or rectum. This is also a rare species.

Each type of colorectal cancer may have different characteristics, treatment options, and prognoses. The diagnosis and treatment plan is determined according to the pathological type and stage of the tumor and the general health condition of the patient. Therefore, pathological examination is extremely important for a person diagnosed with colorectal cancer. Important receptors and molecular markers to be examined in colorectal cancer include Epidermal Growth Factor Receptor (EGFR), HER2/neu, KRAS and NRAS gene mutations, Microsatellite Instability (MSI) and Altered Mismatch Repair (dMMR), and Vascular Endothelial Growth Factor (VEGF). EGFR controls cell growth and is targeted in some treatments. HER2 plays a role in cell division and may be overexpressed in some cancers. KRAS and NRAS mutations are used to predict response to treatment. MSI and dMMR indicate defects in DNA repair mechanisms and are important in the response to immunotherapy. VEGF contributes to tumor growth and metastasis and plays an important role in targeted therapies. These markers are critical in the development of personalized treatment strategies in colorectal cancer.

HOW IS TUMOR STAGING DONE?

Tumor staging in colorectal cancer is a system used to determine the extent of spread of cancer. This staging is usually done using the TNM system (Tumor, Lymph Node, Metastasis) and plays an important role in determining the spread of the disease and treatment options.

T (Tumor): T category indicates the size of the tumor at its primary location and how deeply it penetrates the intestinal wall. T category ranges from T1 to T4, with T1 representing the smallest and least invasive tumor and T4 representing the largest tumor that has spread to surrounding tissues.

N (Lymph Node): The N category indicates whether the cancer has spread to nearby lymph nodes. N0 indicates that there is no cancer in the lymph nodes, while N1, N2 and N3 indicate the degree to which the cancer has spread to the lymph nodes.

M (Metastasis): The M category indicates whether the cancer has spread to other parts of the body (such as the liver or lungs). M0 indicates the absence of distant metastasis, and M1 indicates the presence of metastasis.

Staging is further divided into clinical and pathological staging:

Clinical Staging (cTNM): This is based on information obtained through presurgical diagnostic tests (e.g., endoscopy, CT scan, MRI).

Pathological Staging (pTNM): It is a more precise staging performed as a result of the pathological examination of the tumor and lymph nodes taken after surgery.

Staging in colorectal cancer is critical in determining treatment options and predicting prognosis. In the early stages, surgery is usually the treatment of choice, while in advanced stages systemic treatments and radiotherapy may be necessary.

Image 3: Colon cancer is divided into stages according to the degree of spread to the intestinal surface, lymph node involvement, and distant organ spread.

HOW IS TREATMENT DONE ACCORDING TO STAGES?

Colorectal cancer treatment varies depending on the stage of the cancer. Each stage is determined by the extent of cancer spread, which affects treatment options. Here are general treatment approaches according to stages:

Stage 0 (in situ) Treatment Method:Usually polypectomy or local excision is sufficient. It means complete removal of the tumor through endoscopic procedures.

Phase I Treatment Method: Surgery is the main treatment method. Removing tumors detected by colonoscopy is usually sufficient. Extended surgery may be necessary to determine whether lymph nodes are affected.

Stage II Treatment Method:

Surgery: It is the process of removing the tumor and surrounding healthy tissue, as well as nearby lymph nodes.

Chemotherapy: In some cases, especially in cases where the tumor has high-risk features, adjuvant chemotherapy may be recommended after surgery.

Stage III Treatment Method:

Surgery: Removal of the tumor, surrounding tissues and affected lymph nodes.

Chemotherapy: Adjuvant chemotherapy is the standard treatment after surgery. Chemotherapy can help prevent cancer from recurring.

Stage IV (Metastatic Cancer) Treatment Method:

Systemic Therapies: Chemotherapy, targeted therapies, immunotherapy, and sometimes hormonal treatments. The goal of treatment is usually to keep the disease under control and relieve symptoms.

Palliative Surgery and Radiotherapy: May be used to relieve symptoms.

Metastasectomy: In some cases, surgical removal of metastases may be possible, especially if there are a limited number of metastases in the liver or lung.

General Approach

Supportive Care: At all stages, pain management, nutritional support, and other treatments to relieve symptoms are important.

Personalized Treatment: Genetic and molecular testing can be used to further personalize treatment options.

The treatment plan should be structured taking into account the patient's general health condition, the characteristics of the cancer and personal preferences. Therefore, it is important for patients to discuss their treatment options in detail with their doctors.

WHAT ARE THE DRUGS USED IN TREATMENT?

There are various drugs and treatment methods used in the treatment of colorectal cancer. These treatments can be in the form of chemotherapies, targeted therapies (smart drugs), immunotherapies and sometimes hormonal drugs. Here are examples of these:

Chemotherapy pills

5-Fluorouracil (5-FU): One of the most commonly used chemotherapy drugs, often given together with leucovorin (folinic acid).

Capecitabine: It is a drug taken orally and turns into 5-FU in the body.

Oxaliplatin: Often used in combination with 5-FU and leucovorin (FOLFOX regimen).

Irinotecan: It is often used in combination with 5-FU and leucovorin, known as the FOLFIRI regimen.

Targeted Therapies (Smart Drugs)

Bevacizumab: A targeted antibody against VEGF blocks the formation of tumor blood vessels.

Cetuximab and Panitumumab: Targeted antibodies against EGFR inhibit cell growth and division.

Regorafenib: Multiple kinase inhibitor, effective against many different targets involved in tumor growth.

Immunotherapies

Pembrolizumab and Nivolumab: PD-1 inhibitors help the immune system recognize and destroy tumor cells.

Ipilimumab: CTLA-4 inhibitor helps fight cancer by activating immune system cells.

Each of these treatments is customized and used depending on the characteristics of the disease and the patient's general health condition. It is also important for patients to talk in detail with their doctors about the side effects and effectiveness of these treatments. Because treatment options are constantly evolving, it's best to contact your doctor for the most up-to-date information and recommendations.

HOW SHOULD FOLLOW-UP BE DONE AFTER RECOVERY?

Follow-up of patients after colorectal cancer treatment is vital to detect recurrence early and manage the long-term effects of treatment. Generally, the first few years after treatment are the most intensive follow-up period. This process includes regular physical exams, blood tests (for example, for CEA levels), and imaging tests (colonoscopy, computed tomography (CT), or magnetic resonance imaging (MRI)) when necessary. Colonoscopy is usually recommended in the first year after treatment and every 3-5 years thereafter. Frequency of follow-up may vary depending on the stage of the cancer, the patient's general health condition and the type of treatment. Additionally, patients' lifestyle changes, such as diet, exercise and quitting smoking, can help reduce the risk of cancer recurrence. Psychological support and rehabilitation can also play an important role in this process. Each patient's follow-up plan should be personalized and supported by regular health checks.