Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women in the United States and medical experts agree that if diagnosed early, survival can be most assured. March is Colorectal Cancer Awareness Month and everybody is strongly encouraged to learn more about the disease and go for screening.
Genetic analysis shows that essentially colon and rectal tumors are genetically the same cancer. Symptoms of colorectal cancer typically include rectal bleeding and anemia which are sometimes associated with weight loss and changes in bowel habits.
Most colorectal cancer occurs due to lifestyle and increasing age with only a minority of cases associated with underlying genetic disorders.
It typically starts in the lining of the bowel and if left untreated, can grow into the muscle layers underneath, and then through the bowel wall.
Screening is effective at decreasing the chance of dying from colorectal cancer and is recommended starting at age 50 and continuing until a person is 75 years-old.
The American Cancer Society estimates the number of colorectal cancer cases in the United States for 2014 will be 96,830 new cases of colon cancer and 40,000 new cases of rectal cancer.
Overall, the lifetime risk of developing colorectal cancer is about one in 20 (five percent). This risk is slightly lower in women than in men. A number of other factors can also affect a person’s risk for developing colorectal cancer.
Colorectal cancer is the third leading cause of cancer-related deaths in the United States when men and women are considered separately, and the second leading cause when both sexes are combined. It is expected to cause about 50,310 deaths during 2014.
The good news is that the death rate (the number of deaths per 100,000 people per year) from colorectal cancer has been dropping in both men and women for more than 20 years.
There are a number of likely reasons why; one is that polyps are being found by screening and removed before they can develop into cancers. Screening also allows more colorectal cancers to be found earlier when the disease is easier to cure. In addition, treatment for colorectal cancer has improved over the last several years and as a result, there are now more than one million survivors of it in the United States.
Cancers confined within the wall of the colon are often curable with surgery while cancer that has spread widely around the body is usually not curable and management then focuses on extending the person’s life with chemotherapy.
Colorectal cancer is the third most commonly diagnosed cancer in the world, but just more common in developed countries. Around 60 percent of cases were diagnosed in the developed world. It is estimated that worldwide, in 2008, 1.23 million new cases of colorectal cancer were clinically diagnosed and killed 608,000 people.
Signs, symptoms, causes
The symptoms and signs of colorectal cancer depend on where tumors are located in the bowel, and whether it has spread elsewhere in the body. The classic warning signs include: worsening constipation, blood in the stool, decrease in stool caliber, loss of appetite, loss of weight, and nausea or vomiting in someone over 50 years old.
While rectal bleeding or anemia are high-risk features in those over age 50, other commonly-described symptoms including weight loss and change in bowel habit are typically only concerning if associated with bleeding.
Greater than 75-95 percent of colon cancer occurs in people with little or no genetic risk. Other risk factors include older age, being a male, high intake of fat, alcohol or red meat, obesity, smoking and a lack of physical exercise. Approximately 10 percent of cases are linked to insufficient activity. The risk for alcohol appears to increase at greater than one drink per day.
People with inflammatory bowel disease (ulcerative colitis and Crohn’s disease) are also at increased risk of colon cancer. The risk is greater the longer a person has had the disease and the worsening severity of inflammation.
Those with a family history in two or more first-degree relatives have a two to threefold greater risk of disease and this group accounts for about 20 percent of all cases. A number of genetic syndromes are also associated with higher rates of colorectal cancer.
Experts agree the best way to learn about the disease and ways to overcome it is by talking with your doctor.