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Colorectal cancer is a primary, malignant neoplasm originating in the lining of the lining of the colon. It is one of the most common malignant neoplasms. Colorectal cancers include colon cancer, colorectal cancer, and rectal cancer. What are the symptoms of colon cancer and how to treat it?

Colorectal canceraccording to the World He alth Organization data is the second most common malignant neoplasm occurring in women and the third in men. Colorectal canceraccounts for 10% of all human malignanciesand has an estimated mortality rate of approximately 690,000 deaths per year, accounting for8% of all cancer deaths.

This cancer most often affects people over 40, except for genetically determined neoplasms, then this disease may appear at an earlier age. In terms of histology, colorectal cancer is the most common (80%) adenocarcinoma.

Colorectal cancer - causes

The causes of colorectal cancer are not fully understood.The development of cancer is the result of many years of exposure to risk factors , both environmental and genetic.

This exposure leads to an imbalance of cells, which results in the formation of many types of mutations, which result in the deactivation of genes that inhibit the development of cancer or the strengthening of genes promoting its development.

There are two pathways to the development of colorectal cancer:

  1. adenoma- cancer in which the progression of changes from benign colorectal adenoma to invasive cancer is observed. The process of cancer development occurs here when a mutation in the APC inhibitory gene occurs, which entails further mutations in the genes inhibiting tumor growth, which leads to chromosomal instability, and consequently to the development of colorectal cancer.
  2. so-called "Serrated changes" , the essence of which is a mutation leading to the inhibition of repair genes, and in the next stage to the activation of oncogenes, i.e. substances that cause the development of cancer.

The most important role in the development of colorectal cancer is played by long-term exposure to risk factors that favor the development of cancer. These factors can be divided into dependent environmental factorsfrom humans and genetic factors, therefore not modifiable by humans.

Colorectal cancer - risk factors

An inappropriate lifestyle leads to colorectal cancer. The following risk factors for developing colorectal cancer are:

  1. Improper diet is a key factor in the development of colorectal cancer.It is believed thatpoor diet is responsible for as much as 70% of colorectal cancer. It is believed that people who consume too much red meat, especially fried, and saturated fat are particularly at risk of developing colorectal cancer. Insufficient consumption of vegetables and fruits also promotes the development of colon cancer. Until recently, it was believed that consuming a large amount of fiber and omega-3 fatty acids reduces the risk of cancer, but now it is assumed that these ingredients do not have a protective effect on the development of the disease.
  2. Alcohol consumption is also an important risk factor.It has been shown that people who consume more than 45 g of ethanol per day have a 1.4-fold increased risk of developing the disease. People who consume less alcohol are also at increased risk.
  3. Obesity and overweight are a big risk factor for developing colorectal cancer.It is assumed that a BMI over 30 increases this risk twice. Overweight and obesity are associated with 11% of colorectal cancer cases, and 25-33% of colorectal cancer patients have associated modifiable risk factors: obesity and inactivity.
  4. Lack of physical activity , even in the absence of overweight, is also a factor predisposing to the development of cancer. Physical activity reduces the risk of cancer development by reducing insulin resistance, accelerating metabolism and accelerating intestinal peristalsis.
  5. The last modifiable risk factor is smoking.Smoking increases the risk of developing colorectal cancer by 1.25 times, and also increases the risk of dying from this disease. The risk increases with the number of cigarettes smoked and the years of addiction. The risk does not decrease to zero until 30 years after stopping smoking.

Certain diseases also predispose to the development of colorectal cancer. These include:

  • diabetes
  • inflammatory bowel diseases
  • acromegaly

Ok. 20% of colorectal cancers occur in families , of which about 2-3% are caused by syndromes of increased predisposition to cancer development, they include:

  • Lynch syndrome - This is a genetic syndrome that is inherited in a waydominant, increasing the risk of not only colorectal cancer, but also endometrial cancer, kidney cancer, skin cancer and bile duct cancer. The risk of developing colorectal cancer increases by 80% in this syndrome. Cancer in this syndrome appears more often than in the general population, around 40 years of age
  • familial colorectal cancer type X - There is no increased risk of neoplasms other than colorectal cancer in the syndrome, this cancer also appears slightly later than in Lynch's syndrome
  • familial adenomatous polyposis (FAP) - this disease is manifested by the presence of multiple adenomas in the lumen of the large intestine, which predispose to the development of colorectal cancer. The risk of developing cancer in this disease is close to 100%. The FAP team also predisposes to the development of other malignant and benign neoplasms
  • Peutz-Jeghers syndrome - this is a syndrome of increased predisposition to the development of neoplasms, characterized by the presence of polyps in the gastrointestinal tract. The risk of developing colorectal cancer in this syndrome at the age of 40 is approx. 3%

Colorectal cancer - symptoms

The course of colorectal cancer may be asymptomatic for many years. Symptoms result from tumor infiltration into adjacent structures, tumor growth within the intestinal lumen, and the presence of distant metastases.

Symptoms of colorectal cancer include:gastrointestinal bleeding (especially blood in the stools), abdominal pain, change in bowel habits with alternating diarrhea and constipation, a feeling of incomplete bowel movements and narrowing of the stools (also called 'pencil-shaped stools'), unintentional weight loss.

The growth of the tumor into the intestinal lumen may close its lumen and, as a result, mechanical obstruction of the intestines, and occult bleeding from the lower gastrointestinal tract may lead to anemia.

Read:Gastrointestinal bleeding

Colorectal cancer - diagnosis

The basic examination to diagnose colorectal cancer is colonoscopy. This examination allows you to see the intestinal lumen and to take specimens for histopathological examinations on the basis of which the final diagnosis is made.

Additionally, pre-cancerous lesions may be removed during the colonoscopy. Abdominal ultrasound and computed tomography in search of metastases to distant organs are also routinely performed.

In the case of colorectal cancer, additional tests are also performed - morphology often shows anemia due to latent gastrointestinal bleeding, the most common is also a positive resultfecal occult blood tests.

In colorectal cancer, there is a non-specific tumor marker that is tested in the patient's blood - it is a carcinoembryonic antigen (CEA). However, it is not relevant for the diagnosis of colorectal cancer, but it is used to monitor the effectiveness of treatment and the occurrence of relapses after treatment.

Colorectal cancer treatment

The most important factor in selecting a method and treatment plan is the assessment of the stage of the disease, the presence of distant metastases and the tumor infiltrating structures adjacent to the large intestine that cannot be surgically removed.

The primary treatment is to remove the colon tumor along with the adjacent lymph nodes.In some stages of colorectal cancer, pre-operative treatment such as radiation therapy or chemotherapy is used to reduce the tumor mass. which makes the operation easier.

In the case of colorectal cancer occurring in the rectum, such treatment enables the removal of the tumor while preserving the anal sphincter, which significantly affects the patient's quality of life after surgery. Surgical treatment may also include removal of liver or lung metastases.

Complementary treatment includes radiotherapy and chemotherapy or a combination method. The choice of treatment depends mainly on the location of the tumor.

In the case of a tumor located in the colon, chemotherapy is used, if the patient's condition is good, it is used in the case of metastases to the lymph nodes and if there is a risk of postoperative complications.

In the case of rectal cancer, radiochemotherapy is most often used, in the case of unfavorable prognostic factors or when radiotherapy was not used before surgery.

In the case of inoperable tumors, chemotherapy is used, the destruction of the tumor tissue with the laser method, and the widening of the narrowing of the intestine through the implantation of stents expanding its lumen.

Colorectal cancer - prognosis

Colorectal cancer patients' survival strongly depends on the clinical stage.The five-year survival rate in colorectal cancer is around 65-70%.

The prognosis depends on the depth of the tumor infiltration, its location, involvement of regional lymph nodes, the presence of metastases or the stage of the disease.

The key prognostic is the depth of the invasion deep into the wall of the large intestine. Along with the depth of the infiltration of the organ wall, the risk of recurrence after radical treatment, lymph node involvement and the presence of distant metastases increases. Sheer sizethe tumor is not prognostically significant.

Location is also a prognostic factor -colon locationis a prognostic factor

.

Colon cancer prevention

Colorectal cancer prevention includes lifestyle modifications and the elimination of modifiable risk factors -stopping alcohol and smoking, and including vegetables and fruits in the diet.

Read:How many vegetables and fruits can you eat in one day?

Screening is also very important. Such examinations include colonoscopy, which allows for the assessment of the intestinal lumen and the identification and possible removal of harmless precancerous lesions such as adenomatous polyps.

It is recommended to perform a prophylactic colonoscopy in every person over 50 years of ageand repeat this examination every 10 years. This examination is included in the colorectal cancer prevention program, and is free of charge for people over 50 years of age.

In patients with syndromes predisposing to cancer, it is recommended to perform colonoscopy every year from the age of 10-12.

Colorectal cancer is one of the most common types of cancer. One should pay attention to modifiable risk factors for cancer development and try to eliminate them. Eating a he althy diet, not smoking, and exercising can greatly reduce the risk of developing colorectal cancer.

Performing preventive examinations after the age of 50 may allow for an early diagnosis of a cancer or a minor precancerous condition, and the implementation of appropriate treatment allows for a cure.

In the event of alarming symptoms, such as unintentional weight loss or lower gastrointestinal bleeding, contact your doctor and perform a colonoscopy, thanks to which it is possible to establish the diagnosis and implement treatment.

Read also:

  • Anal cancer - causes, symptoms and treatment of anal cancer
  • Colon cancer: causes, symptoms, treatment
  • Rectal cancer: causes, symptoms, treatment
About the authorBow. Agnieszka MichalakA graduate of the First Faculty of Medicine at the Medical University of Lublin. Currently a doctor during postgraduate internship. In the future, she plans to start a specialization in pediatric hematooncology. She is particularly interested in paediatrics, hematology and oncology.

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Oncology