Colorectal cancer represents, by its frequency, the third cancer in the man and the second in the woman. Its frequency increases after 45 years. It is found in 73% of cases in the colon and the recto-sigmoid region, and in 27% of cases in the rectum. The median age of diagnosis is 72 years for men and 75 years for women.

• SYMPTOMS

  Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they'll likely vary, depending on the cancer's size and location in your large intestine.
  
  Signs and symptoms of colon cancer include:
  
  • A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool, that lasts longer than four weeks
  • Rectal bleeding or blood in your stool
  • Persistent abdominal discomfort, such as cramps, gas or pain
  • A feeling that your bowel doesn't empty completely
  • Weakness or fatigue
  • Unexplained weight loss
  

• DIAGNOSIS

  For colon cancer:
  by total colonoscopy, under brief general anesthesia, which makes it possible to visualize the lesion, to perform biopsies and to remove most of the observed polyps
  
  For rectal cancer, more accessible:
  the diagnosis is made by the clinical examination thanks to the rectal examination and by the rectoscopy which allows biopsies. This examination must be completed by a colonoscopy. If a cancer is detected, its extent will be appreciated by other examinations: endorectal ultrasound, x-rays, CT scan or MRI for lymph node, pulmonary or hepatic metastases, and various liver tests (blood tests), the dosage of which is Carcino Embryonic Antigen (CEA).

• TREATMENT

  The type of treatment your doctor recommends will depend largely on the stage of your cancer. The three primary treatment options are surgery, chemotherapy and radiation.
  
  • Surgery for early-stage colon cancer
  If your colon cancer is very small, your doctor may recommend a minimally invasive approach to surgery, such as:
  
  - Removing polyps during a colonoscopy : If your cancer is small, localized and completely contained within a polyp and in a very early stage, your doctor may be able to remove it completely during a colonoscopy.
  - Endoscopic mucosal resection : Removing larger polyps may require also taking a small amount of the lining of the colon or rectum in a procedure called an endoscopic mucosal resection.
  - Minimally invasive surgery : Polyps that can't be removed during a colonoscopy may be removed using laparoscopic surgery. In this procedure, your surgeon performs the operation through several small incisions in your abdominal wall, inserting instruments with attached cameras that display your colon on a video monitor. The surgeon may also take samples from lymph nodes in the area where the cancer is located.
  
  • Surgery for invasive colon cancer
  If the cancer has grown into or through your colon, your surgeon may recommend:
  
  - Partial colectomy : During this procedure, the surgeon removes the part of your colon that contains the cancer, along with a margin of normal tissue on either side of the cancer. Your surgeon is often able to reconnect the healthy portions of your colon or rectum. This procedure can commonly be done by a minimally invasive approach (laparoscopy).
  
  Surgery to create a way for waste to leave your body. When it's not possible to reconnect the healthy portions of your colon or rectum, you may need an ostomy. This involves creating an opening in the wall of your abdomen from a portion of the remaining bowel for the elimination of stool into a bag that fits securely over the opening.
  
  Sometimes the ostomy is only temporary, allowing your colon or rectum time to heal after surgery. In some cases, however, the colostomy may be permanent.
  
  - Lymph node removal : Nearby lymph nodes are usually also removed during colon cancer surgery and tested for cancer.
  
  • Surgery for advanced cancer
  If your cancer is very advanced or your overall health very poor, your surgeon may recommend an operation to relieve a blockage of your colon or other conditions in order to improve your symptoms. This surgery isn't done to cure cancer, but instead to relieve signs and symptoms, such as bleeding and pain.
  
  In specific cases where the cancer has spread only to the liver but your overall health is otherwise good, your doctor may recommend surgery to remove the cancerous lesion from your liver. Chemotherapy may be used before or after this type of surgery. This approach provides a chance to be free of cancer over the long term.
  
  • Chemotherapy
  Chemotherapy uses drugs to destroy cancer cells. Chemotherapy for colon cancer is usually given after surgery if the cancer has spread to lymph nodes. In this way, chemotherapy may help reduce the risk of cancer recurrence and death from cancer. Sometimes chemotherapy may be used before surgery as well, with the goal of shrinking the cancer before an operation. Chemotherapy before surgery is more common in rectal cancer than in colon cancer.
  
  Chemotherapy can also be given to relieve symptoms of colon cancer that has spread to other areas of the body.
  
  • Radiation therapy
  Radiation therapy uses powerful energy sources, such as X-rays, to kill cancer cells, to shrink large tumors before an operation so that they can be removed more easily, or to relieve symptoms of colon cancer and rectal cancer. Radiation therapy either alone or combined with chemotherapy is one of the standard treatment options for the initial management of rectal cancer followed by surgery.
  
  • Immunotherapy
  Some patients with advanced colon cancer have a chance to benefit from immunotherapy with antibodies such as pembrolizumab (Keytruda) and nivolumab (Opdivo). Whether a colon cancer has the chance to respond to these immunotherapies can be determined by a specific test of the tumor tissue.
  
  Ref : https://www.mayoclinic.org/diseases...

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