Colorectal cancer
Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine).[5] Signs and symptoms may include blood in the stool, a change in bowel movements, weight loss, abdominal pain and fatigue.[9] Most colorectal cancers are due to old age and lifestyle factors, with only a small number of cases due to underlying genetic disorders.[2][3] Risk factors include diet, obesity, smoking, and lack of physical activity.[2] Dietary factors that increase the risk include red meat, processed meat, and alcohol.[2][4] Another risk factor is inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis.[2] Some of the inherited genetic disorders that can cause colorectal cancer include familial adenomatous polyposis and hereditary non-polyposis colon cancer; however, these represent less than 5% of cases.[2][3] It typically starts as a benign tumor, often in the form of a polyp, which over time becomes cancerous.[2]
For cancer of the anus, see Anal cancer.Colorectal cancer
- Colon cancer
- rectal cancer
- bowel cancer
- Blood in stool
- change in bowel movements
- unintentional weight loss
- vomiting
- fatigue[1]
- Diet
- obesity
- smoking
- lack of physical activity
- alcohol use[2][4]
Tissue biopsy during a sigmoidoscopy or colonoscopy[1]
Screening from age of 45 to 75
Five-year survival rate 65% (US)[6]
9.4 million (2015)[7]
551,000 (2018)[8]
Colorectal cancer may be diagnosed by obtaining a sample of the colon during a sigmoidoscopy or colonoscopy.[1] This is then followed by medical imaging to determine whether the disease has spread.[5] Screening is effective for preventing and decreasing deaths from colorectal cancer.[10] Screening, by one of a number of methods, is recommended starting from the age of 45 to 75. It was recommended starting at age 50 but it was changed to 45 due to increasing amount of colon cancers.[10][11] During colonoscopy, small polyps may be removed if found.[2] If a large polyp or tumor is found, a biopsy may be performed to check if it is cancerous. Aspirin and other non-steroidal anti-inflammatory drugs decrease the risk of pain during polyp excision.[2][12] Their general use is not recommended for this purpose, however, due to side effects.[13]
Treatments used for colorectal cancer may include some combination of surgery, radiation therapy, chemotherapy, and targeted therapy.[5] Cancers that are confined within the wall of the colon may be curable with surgery, while cancer that has spread widely is usually not curable, with management being directed towards improving quality of life and symptoms.[5] The five-year survival rate in the United States was around 65% in 2014.[6] The individual likelihood of survival depends on how advanced the cancer is, whether or not all the cancer can be removed with surgery, and the person's overall health.[1] Globally, colorectal cancer is the third most common type of cancer, making up about 10% of all cases.[14] In 2018, there were 1.09 million new cases and 551,000 deaths from the disease.[8] It is more common in developed countries, where more than 65% of cases are found.[2] It is less common in women than men.[2]
Signs and symptoms[edit]
The signs and symptoms of colorectal cancer depend on the location of the tumor in the bowel, and whether it has spread elsewhere in the body (metastasis). The classic warning signs include: worsening constipation, blood in the stool, decrease in stool caliber (thickness), loss of appetite, loss of weight, and nausea or vomiting in someone over 50 years old.[15] Around 50% of people who have colorectal cancer do not report any symptoms.[16]
Rectal bleeding or anemia are high-risk symptoms in people over the age of 50.[17] Weight loss and changes in a person's bowel habit are typically only concerning if they are associated with rectal bleeding.[17][18]
Preliminary in-vitro evidence suggests lactic acid bacteria (e.g., lactobacilli, streptococci or lactococci) may be protective against the development and progression of colorectal cancer through several mechanisms such as antioxidant activity, immunomodulation, promoting programmed cell death, antiproliferative effects, and epigenetic modification of cancer cells.[212]