Definition of colon cancer: Cancer that forms in the tissues of the colon (the longest part of the large intestine). Most colon cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).
Estimated new cases of colon and rectal cancer in the United States in 2016: 95,270 (colon); 39,220 (rectal)
Colorectal cancer is the third most common non-skin cancer in both men and women. Men and women have similar incidence rates through age 39; at and above age 40, rates are higher in men. Differences exist between racial/ethnic groups in both incidence and mortality. African Americans have higher mortality rates than all other racial/ethnic groups and higher incidence rates than all except American Indians/Alaska Natives. Incidence rates are lowest among Hispanics and Asians/Pacific Islanders.
Risk factors for colorectal cancer include increasing age, colorectal polyps, a family history of colorectal cancer, certain genetic mutations, excessive alcohol use, obesity, being physically inactive, cigarette smoking, and a history of inflammatory bowel disease. Effective colorectal cancer screening tests include the fecal occult blood test, sigmoidoscopy, and colonoscopy. Standard treatments for colorectal cancer include surgery, chemotherapy, immunotherapy, radiation therapy, cryosurgery, radiofrequency ablation, and targeted therapy.
The following stages are used for colon cancer:
Stage 0 (Carcinoma In Situ)
In stage 0, abnormal cells are found in the mucosa (innermost layer) of the colon wall. These abnormal cells may become cancer and spread. Stage 0 is also called carcinoma in situ.
Stage I
In stage I, cancer has formed in the mucosa (innermost layer) of the colon wall and has spread to the submucosa (layer of tissue under the mucosa). Cancer may have spread to the muscle layer of the colon wall.
Stage II
Stage II colon cancer is divided into stage IIA, stage IIB, and stage IIC.
- Stage IIA: Cancer has spread through the muscle layer of the colon wall to the serosa(outermost layer) of the colon wall.
- Stage IIB: Cancer has spread through the serosa (outermost layer) of the colon wall but has not spread to nearby organs.
- Stage IIC: Cancer has spread through the serosa (outermost layer) of the colon wall to nearbyorgans.
Stage III
Stage III colon cancer is divided into stage IIIA, stage IIIB, and stage IIIC.
In stage IIIA:
- Cancer may have spread through the mucosa (innermost layer) of the colon wall to thesubmucosa (layer of tissue under the mucosa) and may have spread to the muscle layer of the colon wall. Cancer has spread to at least one but not more than 3 nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes; or
- Cancer has spread through the mucosa (innermost layer) of the colon wall to the submucosa (layer of tissue under the mucosa). Cancer has spread to at least 4 but not more than 6 nearby lymph nodes.
In stage IIIB:
- Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall or has spread through the serosa but not to nearby organs. Cancer has spread to at least one but not more than 3 nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes; or
- Cancer has spread to the muscle layer of the colon wall or to the serosa (outermost layer) of the colon wall. Cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
- Cancer has spread through the mucosa (innermost layer) of the colon wall to the submucosa(layer of tissue under the mucosa) and may have spread to the muscle layer of the colon wall. Cancer has spread to 7 or more nearby lymph nodes.
In stage IIIC:
- Cancer has spread through the serosa (outermost layer) of the colon wall but has not spread to nearby organs. Cancer has spread to at least 4 but not more than 6 nearby lymph nodes; or
- Cancer has spread through the muscle layer of the colon wall to the serosa (outermost layer) of the colon wall or has spread through the serosa but has not spread to nearby organs. Cancer has spread to 7 or more nearby lymph nodes; or
- Cancer has spread through the serosa (outermost layer) of the colon wall and has spread to nearby organs. Cancer has spread to one or more nearby lymph nodes or cancer cells have formed in tissues near the lymph nodes.
Stage IV
Stage IV colon cancer is divided into stage IVA and stage IVB.
- Stage IVA: Cancer may have spread through the colon wall and may have spread to nearbyorgans or lymph nodes. Cancer has spread to one organ that is not near the colon, such as the liver, lung, or ovary, or to a distant lymph node.
- Stage IVB: Cancer may have spread through the colon wall and may have spread to nearbyorgans or lymph nodes. Cancer has spread to more than one organ that is not near the colon or into the lining of the abdominal wall.
All information was taken from the NCI (National Cancer Institute)
