Kirstie Alley died from colon cancer. Here are the risk factors and signs of the disease.

Kirstie Alley died from colon cancer, her representative confirmed this week. The actor's family announced Monday that she had died at age 71, saying the cancer was "only recently discovered." An estimated 151,030 people will be diagnosed with colorectal cancer in the U.S. this year, according to the Colorectal Cancer Alliance. 

Colon cancer begins in the large intestine, or colon, the final part of the digestive tract, and usually beings as small, noncancerous clumps of cells in the colon, according to the Mayo Clinic. These clumps of cells, called polyps, can develop into cancer when healthy cells mutate, leading to colon cancer. 

The polyps that develop may be small and produce few symptoms, if any. Because of this, regular screening tests are recommended for adults 45 or older, in order to examine potential polyps and identify and remove polyps before they turn into cancer.

Some of the symptoms of colon cancer include a change in bowel habits, like diarrhea or constipation; rectal bleeding or blood in your stool; discomfort like cramps or gas; and unexplained weight loss, according to the clinic.

Colon cancer typically affects older adults, but can happen at age, according to Mayo Clinic. Things like smoking, having diabetes or obesity, and eating a low-fiber diet can increase risk. African Americans are also at a higher risk for colon cancer. A family history of colon cancer and a history of chronic inflammatory diseases of the colon, like ulcerative colitis and Crohn's disease, are also among the factors that could increase risk. 

While the overall rates of this type of cancer have decreased by about 1% per year, this mostly reflects the rate in older adults. The rate has actually increased by 2% for people under 50 and by 1% for people ages 50 to 64, according to the American Cancer Society. 

Patients 45 and older should talk to their doctor about screenings, such as stool examinations or visual exams, like a colonoscopy. Eating a healthy diet and managing your weight is a way to mitigate risk. 

Mayo Clinic recommends eating fruits and vegetables, exercising, drinking alcohol in moderation and quitting smoking.

Treatment for colon cancer can include surgery to remove the polyps or cancer cells as well as chemotherapy, according to the American Cancer Society. Treatment can depend on the stage of cancer, for example, stage II colon cancer can grow through the wall of the colon, and patients may need surgery to remove part of the colon, called a partial colectomy. 

Stage IV colon cancer might not be treated by surgery, but by chemotherapy. Sometimes, a colectomy or diverting colostomy – cutting the colon above the level of the cancer and attaching the end to an opening in the skin on the belly to allow waste out – may be performed. 

In announcing her death, Alley's kids, True and Lillie Park, thanked the doctors and nurses at Moffitt Medical Center in Tampa, Florida, for her care. "As iconic as she was on screen, she was an even more amazing mother and grandmother," they said.

The five-year survival rate for localized colon cancer, meaning there is no sign that the cancer has spread outside of the colon or rectum, is 91%, according to American Cancer Society. However, the five-year survival rate for distant colon cancer – when the cancer has spread to distant parts of the body – dips to 14%. It is unclear what stage of cancer Alley had or how recently she had been diagnosed.