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What is colon cancer, and what are the causes, risk factors, and symptoms that might lead to it?


What is colon cancer?

Colon cancer is the growth of a malignant tumour that affects the section of the intestine, also known as the large intestine. This section includes the small intestine’s end to the rectum’s beginning. Sometimes colon cancer also affects the rectal area, and this disease is referred to as colorectal cancer.

Who is affected?

Colon cancer is the most common cancer in our country if men and women are counted together. However, it has been a gradual decrease in the prevalence of frequency that occurred in men and is currently practically equivalent in both sexes.

According to data from the Spanish Digestive System Foundation (FEAD), in 2020, the estimated incidence in Spain was more than 44,000 new cases, 9.2% of all cancers diagnosed. It is the second most common tumour in men after the prostate and the second in women after the breast. 

What are the causes?

The causes of colon cancer are multiple, which means that it is considered a multifactorial disease in which two types of factors are involved:

Environmental factors:

Alcohol and tobacco use.

A diet is rich in fat and red meat and low in fruits, vegetables and fibre.

Obesity and high caloric intake: are frequent antecedents in people suffering from this disease.

Genetic factors: colorectal cancer runs in families in one in three patients, and the genetic association is only apparent in a minority of cases. These relatives may have also had cancer of the colon or other organs, such as the breast or pancreas, or have diseases that predispose to the appearance of polyps in this organ.

Are there risk factors?

Colon cancer presents the following aspects as risk factors:

Age: the presence of these rare diseases before the age of 40 begins to increase and reaches a maximum of 75 years. However, familial forms of colon cancer account for approximately one in three or four cases and can appear at earlier ages.

A history of multiple polyps in the colon (familial polyposis), colon cancer and even other cancers such as breast or genitourinary: are circumstances that must be considered to increase surveillance.

What symptoms can alert us to colon cancer?

We can look at several initial symptoms that indicate a change in the colon wall.

Change in the rhythm of bowel movements: present unusual diarrhoea or constipation.

Change in stool calibre: tape-shaped stool, for example.

Other frequent symptoms of colon cancer are:

  • Chronic anaemia is due to the loss of occult blood in faeces.
  • More noticeable blood loss: more in the case of colorectal cancer. This visible blood can be dark or red.
  • The sensation of not having finished the stool.
  •  More nonspecific abdominal discomfort.
  • Significant tiredness and weight loss: usually occur in more advanced stages of the disease.

How is this disease diagnosed?

Early diagnosis of colon cancer is essential because if it is detected in the early stages with no symptoms, there is a greater chance of overcoming a type of tumour in which cure rates are high. 

In fact, according to estimates by the AECC, survival for this disease at five years of being detected early stands at 64% of patients, a figure higher than the average for European countries, which is 57%.

The diagnosis is based on the usually ordered combination of a series of tests that finally allow the taking of samples and their anatomopathological study:

Occult blood test in the stool: it is used to find out if there is blood in the stool and that it is not visible to the naked eye. If it comes out positive, it is a sign that there may be some bleeding in the digestive tract, so you have to continue doing more explorations.

Physical examination: it is worth highlighting the usefulness of a digital rectal examination, which the doctor will carry out to rule out the presence of physical abnormalities, lumps or pain in the rectum, although other areas of the colon will be challenging to access.

Double-contrast barium enema: it is a type of x-ray focused on the colon and rectum, taken after the patient has been given an enema with a substance that defines the shape of the inner wall of the colon.

Colonoscopy: upon clinical suspicion or screening for occult blood in faeces, or as part of the surveillance indicated by the history, it is used to observe the interior of the digestive tract through a tube that is inserted through the rectum and take samples of the tissue or suspicious lesions (biopsy) for later analysis. It constitutes the most definitive test, and whenever it is available, it reduces the need for radiographic studies that may be inconclusive or subsequently require the performance of this test.

What possible treatment has colon cancer?

When colon cancer has already been diagnosed, treatment is aimed at removing all the cancerous tissue by surgery. However, depending on its degree of evolution, this operation will have a curative purpose. It may require other additional treatments, and even, in advanced cases, it will only constitute a palliative treatment. Hence, early identification is especially relevant.

In cases where surgery cannot ensure complete removal of cancerous tissue and affected nodes or distant metastases, treatment may sometimes include chemotherapy and radiotherapy.

Ten tips for colon cancer prevention

1. Avoid constipation.

According to several studies, a diet rich in fibre helps reduce waste substances that remain in contact with the colon mucosa, which could reduce the appearance of the first changes that lead to cancer.

2. Watch your diet.

Try to reduce saturated fats as much as possible and reduce the consumption of red meat since obesity and high caloric intake are related, according to some studies, to this type of malignant tumour.

3. Reduce alcohol consumption and avoid tobacco.

Both toxins increase the risk of cancer in this area of ​​the body and other digestive organs.

4. Do regular physical exercise.

Regular exercise help to lower the incidence of colorectal cancer.

5. Pay attention to your bowel movements.

You must know your bowel movements rate well and monitor the stool’s appearance. If you notice visible blood in them, discuss it with your doctor to establish its origin.

6. With age, get regular check-ups.

From the age of 40, make annual visits with your Primary Care doctor and follow his recommendations on performing tests, digital rectal examinations, and, if applicable, determination of occult blood in faeces, specific X-rays and colonoscopy.

7. Genetic inheritance, a risk factor. 

Genetic factors significantly influence the appearance of this disease, so you must communicate your family and personal history to your doctor because they can lead to the need for genetic studies to establish a follow-up plan and good advice for you and your family.

8. If there is a history, you will need more follow-up

Suppose you have a family history of risk (relatives who have suffered certain types of cancer or multiple polyps in the colon). In that case, you need a closer follow-up to detect the first potential changes in the mucosa of the colon.

9. Watch your colon if you suffer from the stomach. 

If you suffer from intestinal diseases such as inflammatory bowel disease (for example, ulcerative colitis or Crohn’s disease ), surveillance of your colon should also be more frequent.

10. Early detection is possible. 

If the first tests give positive results, follow the recommendations to perform a colonoscopy, take a biopsy and remove polyps to detect any problem early.