Colon cancer is one of the most common cancers in the United States. It forms in the colon, part of the large intestine that stores waste before it’s removed from your body during a bowel movement. The colon has four sections: cecum, ascending colon, transverse colon, and descending colon. Cancer can form in any area of this organ; however, it tends to develop more often in the cecum or the rectum (the lowest part of the colon).
What are some symptoms? There are no early symptoms of colon cancer. This is why getting screened regularly is so important. Many people begin having symptoms when they already have advanced cancer. The symptoms tend to develop slowly and may include:
– Rectal bleeding, especially if it’s bright red blood, mixed with stool or a type that is pink, light red, or looks like tar
– A change in the size or frequency of bowel movements over weeks or months
– Abdominal pain, often in the lower abdomen (backside) and sometimes accompanied by weight loss and fatigue.
Cancer can develop after someone reaches adulthood; however, colon cancer is most common between ages 50 and 70—about 5 percent of colon cancers from before age 40. People with colon polyps are at higher risk for colon cancer than those who don’t have colon polyps. The colon is a long, hollow tube about 5 feet long and an inch in diameter. Colon cancer occurs when the cells in the colon lining become abnormal and start to grow out of control. These cells form tumors and invade nearby structures and tissues.
What causes colon cancer? There are many risk factors for colon cancer, including:
– A personal history of colon cancer or polyps
– Family history. You have a higher chance of colon cancer if other family members have had it too. This suggests that some colon cancers may be caused by inherited (genetic) abnormalities passed from one generation to another within your family. Cancer risk also increases with age; however, people younger than 50 can get colon cancer. People who have inherited colon cancer syndromes, such as familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC), often develop colon cancer at an earlier age, even before they reach their forties or fifties.
What are the stages of colon cancer? The stage of colon cancer refers to how far the disease has spread beyond your colon. The extent of the spread is determined by examining the tissue under a microscope in a lab to see if there are any abnormal cells. Your treatment plan will be based on your stage at diagnosis. As with all cancers, colon cancer is staged from I (1) to IV (4). The lower the colon cancer stage, the better your chance of curing. Doctors also look at where colon tumors are located and whether nearby lymph nodes contain cancer cells.
– Stage 0: Cancer is found in the inner lining of the colon or rectum and may have grown into nearby tissues or lymph nodes; however, it has not spread beyond these areas.
– Stage 1: The tumor is 5 centimeters (cm) or smaller, and all four of its borders (where it begins and ends) can be clearly defined; the tumor only involves the inner layer of the colon wall; it’s been completely removed by surgery, or it’s inside a colon that remains open after colon surgery. There is no sign that the colon cancer has grown through the colon wall into other organs. Cancer may have spread to nearby lymph nodes but not beyond.
– Stage 2: The tumor is more significant than 5 cm in size, or it invades tissue outside of the colon, or it has grown into fat around the colon but not into nearby lymph nodes. The colon may be blocked by a piece of colon cancer (obstruct) and requires surgery to open (unblock). If your doctor finds any noncancerous polyps when removing colon cancer, they will remove them.
– Stage 3: The tumor continues to grow bigger. It may have also spread to surrounding areas like the colon wall to the lymph nodes near the colon but has not spread to other parts of the body. Also, there are no signs of cancer in any other part of the colon or rectum.
– Stage 4: One or both of these apply to stage 4 colon cancer: the tumor continues to grow bigger but has not spread outside of the colon wall, or strong evidence shows that colon cancer is growing into nearby lymph nodes. Additionally, cancer can be found in other organs away from the colon, such as the liver, lungs, bones, lining around your heart.