What are the symptoms of colon cancer?
The family of supermodel Pat Cleveland has revealed she is battling colon cancer after she was diagnosed in March - a diagnosis that came after months of digestive issues.
The 68-year-old American model underwent emergency surgery after a scan found a cancerous tumour blocking her colon.
Colon cancer, often grouped with rectal cancer due to the similarities, is the third most common cancer diagnosed in men and women in the United States, according to the American Cancer Society.
In 2019, there have been an estimated 101,420 new cases of colon cancer.
This is everything you need to know about colon cancer, the symptoms and treatment.
What is colon cancer?
Colon cancer is cancer of a portion of the large intestine (large bowel).
The colon, a five-foot-long muscular tube that is part of the digestive system and responsible for absorbing water and salt from food matter, is split into four parts - the ascending colon, the transverse colon, the descending colon and the sigmoid colon.
Cancer of the colon frequently starts as growths, called polyps, on the inner lining of the colon.
However, not all polyps become cancerous and the likelihood of the polyp turning into cancer is dependent on the type of polyp it is.
There are two main types of polyps, according to the American Cancer Society, Adenomatous polyps (adenomas), which sometimes morph into cancer, and Hyperplastic and inflammatory polyps, which are more common and generally do not cause cancer.
According to the American Cancer Society, other factors that increase the risk of a polyp becoming cancerous include if a polyp is larger than 1cm, if there are more than two polyps found, or if dysplasia, a pre-cancerous condition, is found in the polyp after it is removed.
Adenocarcinomas, a type of tumour that makes up 96 per cent of colorectal cancers, starts in cells that make mucus (the mucosa) to lubricate the inside of either the colon or the rectum.
After starting in the inner-most layer, the cancer can then grow into the walls of the colon.
If the cancer cells reach the wall, they can grow into blood vessels or lymph vessels - increasing the likelihood of the cancer spreading to other parts of the body.
The stages of colon cancer are diagnosed by how deeply the cancer has spread into the wall of the colon.
What are the symptoms of colon cancer?
Because polyps are typically small and rarely produce symptoms, doctors recommend regular screenings for polyps and colon cancer.
If a polyp has turned into cancer, symptoms are usually more noticeable.
Symptoms of colon cancer include changes in bowel habits, such as diarrhoea or constipation, or a change in consistency of stool that lasts for more than four weeks, rectal bleeding or blood in stool, persistent abdominal discomfort, feeling as if your bowel doesnâ€™t completely empty, weakness or fatigue or unexplained weight loss, according to the Mayo Clinic.
However, many people do not experience symptoms, so screenings are important.
According to the Mayo Clinic, screenings typically begin at age 50, but your doctor may recommend earlier screenings if there is a family history of colon cancer.
How many people does it affect and what is the treatment for colon cancer?
In the US, nearly 50,000 men and 50,000 women have been diagnosed with colon cancer this year.
The disease, which is the third leading cause of cancer death in men and women, mainly affects older adults.
Currently, the overall five-year survival rate for colon cancer is 64 per cent, according to the American Society of Clinical Oncology (ASCO), but the death rate for the disease is declining as treatment has improved.
The three primary treatment options for colon cancer are surgery, chemotherapy and radiation, depending on the stage of the cancer, according to the Mayo Clinic.
If the cancer is in an early stage, a minimally invasive surgical option is often used to remove polyps, either during a colonoscopy or through laparoscopic surgery.
For more invasive colon cancer, doctors may recommend a partial colectomy, where a portion of the colon is removed.
If it is impossible to reconnect the colon, an ostomy may also be required - which involves creating an opening in the wall of your abdomen for the elimination of stool.
In addition to the surgical options, chemotherapy drugs to destroy the cancer cells may be used.
Chemotherapy is occasionally used before surgery to shrink the cancer, but is more common in rectal cancer than colon cancer.
Radiation may also be used as a method of shrinking the cancer before surgery.
Less common treatments may include immunotherapy or proton beam therapy.
What risk factors increase the chance of colon cancer?
Old age, African-American race, family history, having an inflammatory intestinal conditions such as ulcerative colitis, a low fibre high-fat diet, a sedentary lifestyle, diabetes, obesity, smoking and alcohol all may increase the risk of developing colon cancer, according to the Mayo Clinic.