Colon cancer

Colorectal carcinoma is not one, and more than 10 various diseases, united under the common name “Colon cancer”. From an anatomical point of view, the large intestine consists of different parts, each of which can be affected by an oncological disease with a specific histological characteristic.

The type of tumors, the stage of the disease, age and comorbidities of the patients are the main indicators, according to which an individual therapeutic strategy is drawn up by the specialists.


Symptoms of colorectal cancer can be:

  • Diarrhea, constipation or feeling, that the bowel movement is partial
  • Light red or very dark blood in the stool
  • Change in stools – become narrower or thinner than usual
  • Abdominal discomfort, like frequent gas, swelling and pain
  • Weight loss for no apparent reason
  • Iron deficiency anemia
  • Constant fatigue

These symptoms can be a signal of other non-oncological diseases. To be diagnosed with colon cancer, they must come on suddenly and be variable. As with other oncological diseases, if detected at an early stage, colon cancer can be cured. In the presence of one or more of the indicated symptoms, it is necessary to consult a gastroenterologist, to order additional tests.

Risk factors

The incidence of colorectal cancer varies among nations. These variations are due both to specificities in national registries, the statistics, the population gene pool, the organization of health care, as well as medical culture and lifestyle. In its essence, the disease has a genetic basis. This does not mean, that patients with colorectal cancer always inherit the disease. A relatively small percentage of patients have a hereditary predisposition to cancer, which increases the risk of developing colorectal cancer, but does not predetermine its appearance. In the majority of patients, there are dozens of genetic defects, even hundreds and accumulate over a lifetime. Collectively, genetic mutations lead to malignant transformation of cells.

Polyps are growths on the inner surface of the colon. They can have different shapes and sizes. In time (months, years) the cells on the surface of the polyps can gradually- but to acquire characteristics, different from those of normal cells.

The malignant transformation of these cells is expressed in their uncontrollable division and the development of the ability to enter the intestinal wall and spread in the body as well as in places adjacent to the primary focus, as well as distant localizations through the blood circulation and lymph.

Diagnostics and screening

The most complete information from the diagnostic methods is provided by the colonoscopy and the biopsy from suspects (suspicious) lesions on the inner surface of the colon, as well as the removal of polyps and their histological examination.

Imaging studies, whatever they are, have a role in specifying the spread of the disease. They cannot definitively prove the origin of the tumors or specify their histology, which is of decisive importance for the formation of an individual therapeutic plan for patients.

The study of tumor markers only complements the process of diagnostic refinement. On the one hand, tumor markers can also increase in non-specific inflammatory processes along the course of the digestive tract. On the other hand, for part of the patients, they may not be excessive and not indicative of the development of an oncological disease. In most cases, markers are relevant in the context of their dynamic regular monitoring during the therapeutic process to assess the therapeutic effect.

Imaging tests such as a PET-CT scan and computed tomography allow doctors to precisely localize the cancer, as well as to assess whether there are metastases in other parts of the body.


Doctors use diagnostic tests, to determine the stage of the disease, therefore, staging may not be complete until all studies have been completed. Staging information helps to develop the patient's treatment plan and the prognosis of the disease. There are different staging systems for different types of cancer.

TNM staging system

The TNM system is one way, which doctors use, to describe the stage of the disease. Doctors use the results of diagnostic tests , to answer the following questions:

Tumor (T) : Has the tumor grown into the wall of the colon or rectum? How many layers of the wall are affected?
Lymph nodes(N) : Has the tumor affected the lymph nodes?? If so, where and to what extent?
Metastases (M) : Has the cancer metastasized to other parts of the body?? If yes, where and to what extent?

The results are combined, to determine the stage of each patient's cancer.

They exist 5 stage: stages 0 (zero) and stages I to IV. The stage provides a general way of describing the cancer, so that doctors can, working together to determine the best treatment.

Tumor (T)

According to the TNM system, the letter T plus a letter or number from 0 to 4 is used, to describe how far the primary tumor has grown into the colon wall. Some stages are divided into smaller groups, which help to describe the tumor in more detail.


The determination of the stage of the disease is carried out in most cases after surgical intervention, histological evaluation of the removed tumor and lymph nodes and taking into account the data from imaging studies on the spread of the disease in the body. Stages are numbered I to IV with corresponding substages.

Of importance for therapy and prognosis is how deep in the bowel wall the tumor has grown, has it affected neighboring organs?, regional or distant lymph nodes, etc. Therefore, removal of lymph nodes during surgery is of particular importance for making the most adequate decision on therapeutic behavior in these patients..

Chemotherapy and radiotherapy can be administered pre-operatively and post-operatively in the appropriate indications for these types of therapy.

Radiation therapy

In rectal carcinomas, the application of rays- Rapia is very often part of the complex treatment. To affect metastatic foci in the liver, lungs and lymph nodes is possible in certain cases (when they are single, large enough and in places accessible for irradiation) the application of stereotactic radiosurgery - a type of radiation therapy. This treatment allows the concentrated application of large fractions of radiation to a precisely defined area. In this way, normal pods are spared- tures and tissues around the tumor focus - for example black- the lung and lung parenchyma.

Medical Oncology

Systemic antitumor drug treatment includes: chemotherapy, endocrine therapy, target (aimed) therapy, Immuno-oncology treatment and some other types of anti-tumor drugs.

Neoadjuvant chemotherapy (preoperative) - treatment, which serves to reduce the tumor volume in order to better carry out surgical treatment or radiation therapy. It helps reduce the risk of developing metastases (scattering from tumor cells settled in different organs).

Adjuvant chemotherapy (prophylactic) - treatment, which occurs at certain stages in some types of tumors, to destroy the remaining single cells in the body after surgery, which can settle in a certain location and after a while begin to actively divide, by forming metastases or re-development of the tumor at the site of its primary development. Modern targeted chemotherapy is often added to classic chemotherapy in adjuvant treatment (aimed) therapy. Hormonal can be applied as an adjuvant (endocrine) therapy.

Curative chemotherapy - aims to slow down and/or stop tumor growth for a different period of time and is aimed at patients, whose disease cannot be cured, but can be controlled for a long time - sometimes for many years.

Modern drug treatment of malignant tumors includes both classical cytotoxic and cytostatic drugs (chemotherapy - antitumor drugs), as well as medicines from the target group (aimed) therapy, which selectively attack specific targets in tumor cells, representing genetic mutations, proven by genetic studies.

Source: Bulgarian Oncological Scientific Society (BOND)

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