Understanding colorectal cancer

Explore this health file to better understand colorectal cancer: its causes, its symptoms but also the means of treatment.

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I. Definition and key figures

Colorectal cancer includes cancer of the colon and rectum, which make up the large intestine, the last part of the digestive tract. [1] 

Colorectal cancer generally begins with the formation of a small mass, which is a benign tumor that develops on the mucous membrane of the colon or rectum. This benign tumor, known as a polyp, can turn into a cancerous tumor. This usually takes between 5 and 10 years. Colorectal cancer develops locally at first, then the cancer cells can spread to other parts of the body if not detected and treated at an early stage. [1] 

Key figures: 
  • Colorectal cancer is the third most common cancer diagnosed in men, after prostate and lung cancer, and the second most common in women, after breast cancer. [1][2] 
  • According to WHO, colorectal cancer was responsible for around 900,000 deaths worldwide in 2022. [3] 
  • Colorectal cancer is the 3rd cancer most common cancer in sub-Saharan Africa, with around 23,400 cases in 2020. [4] 
  • When detected at an early stage, colorectal cancer is curable 9 times out of 10. [5] 

II. Causes

There are several causes that can increase the risk of having colorectal cancer [1][2]: 

  • Age: age increases the risk of developing colorectal cancer. Most cases occur after the age of 50. 
  • Lifestyle: unhealthy habits, such as a diet rich in saturated fats and red meat, and low intake of fiber, fruit, and vegetables, can increase the risk. Overweight, excessive alcohol consumption, smoking and a sedentary lifestyle can also be risk factors for the development of colorectal cancer.  
  • Family history: a family history of colorectal cancer or certain genetic conditions such as Lynch syndrome (genetic predisposition to colorectal and other types of cancer) may be risk factors. 
  • Personal tumor history: the risk is increased in individuals who have already had colorectal cancer.  

III. Symptoms 

Colorectal cancer is often asymptomatic in its early stages. [2] However, as it develops, non-specific symptoms may appear, such as [6]: 

Intestinal transit disorders  

  • Constipation 
  • Diarrhea 
  • Nausea and vomiting 

Blood in the stool  

  • Presence of red or dark blood. 

Signs localized to the abdomen 

  • A mass on palpation of the abdomen 
  • Abdominal pain. 

General symptoms 

  • Anemia, discovered during a blood test 
  • Chronic fatigue (asthenia) 
  • Sudden, unexplained weight loss and loss of appetite. 

These symptoms may also be related to other medical conditions. If you experience any of these symptoms, it is recommended to consult a healthcare professional for an accurate diagnosis. [6]

IV. Prevention

Colorectal cancer prevention involves adopting healthy lifestyles and participating in regular screening programs. [7][8]: 

Adopting a healthy lifestyle: 

  • Eating a diet rich in fiber, fruits, vegetables and whole grains, while limiting consumption of red meat and saturated fats, can reduce the risk of colorectal cancer and cancer in general. 
  • Regular physical activity. 
  • Monitor and maintain a healthy weight. 
  • Limit consumption of alcoholic beverages and give up smoking. 

Getting screened: 

One of the best ways to prevent the onset of colon cancer is to undergo regular screening. Diagnosing the disease at an early stage enables treatment to be initiated quickly, thereby optimizing the chances of recovery. It is therefore strongly recommended that people aged between 50 and 74 undergo a cancer screening test every two years to prevent the risks. The two most common screening methods are: 

  • Immunological test: it is a rapid test performed at home, which detects the presence of blood in the stool, often invisible to the naked eye. It involves taking a stool sample and sending it to a medical biology laboratory. In the event of a positive diagnosis with an immunological test, colonoscopy is generally recommended to confirm the diagnosis. 
  • Colonoscopy: this is a medical imaging procedure that allows the doctor to examine the inside of the colon and rectum using a tube fitted with a camera. This is the most accurate screening method, as it not only detects polyps, but also removes them during the procedure, which can prevent the further development of other cancers.

V. Treatments

Treatment of colorectal cancer depends on a number of factors, such as the stage of the cancer, tumor location and other considerations. The main treatment options for colorectal cancer include [9]: 

  • Surgery 
  • Radiation therapy 
  • Chemotherapy 
  • Targeted therapies 
  • Immunotherapy 

Surgery is the main treatment for colorectal cancer, especially in the early stages. It aims to remove the tumor if it has not spread to other organs. 

If the tumor has invaded neighbouring organs, chemotherapy and radiotherapy may be prescribed before surgery to reduce its size. Chemotherapy may also be prescribed after surgery if the doctor suspects a high risk of recurrence. 

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POI 0944-03/24
[1] Comprendre les cancers du côlon et du rectum | ameli.fr | Assuré 
[2] Cancers du côlon : les points clés – Cancer du côlon (e-cancer.fr) 
[3] Cancer : une charge toujours plus lourde dans le monde et des besoins en services croissants (who.int) 
[4] Afrique subsaharienne : la charge du cancer devrait presque doubler dans les 20 prochaines années | ONU Info (un.org) 
[5] Cancer colorectal : détecté à un stade précoce, il se guérit 9 fois sur 10 | ameli.fr | Assuré 
[6] Cancer du colon ou du rectum : symptômes et diagnostic | ameli.fr | Assuré 
[7] Réduire le risque de cancer colorectal | Société canadienne du cancer 
[8] Le dépistage du cancer colorectal en pratique – Dépistage du cancer colorectal (e-cancer.fr) 
[9] Cancer colorectal (who.int)