Colorectal cancer (CRC), also known as colon cancer, is a cancer that occurs in the large intestine (colon) or rectum and is the third most diagnosed cancer in the U.S., appearing more frequently in older men and women over the age of 50. Colorectal cancer often begins with appearance of small, non-cancerous (benign) growths (polyps) in the lining of the colon that are without symptoms. Some of these polyps can eventually develop into tumors and become colorectal cancer. Not all polyps become cancerous. The risk of polyps developing into cancer depends on the type of polyps, of which there are two main types:   1) Adenomas are considered pre-cancerous because they sometimes become adenocarcinomas, which represent 96% of colorectal cancers. 2) Hyperplastic and inflammatory polyps occur more often and are usually non-cancerous. Additional risks for polyps becoming cancerous include their size, number, or whether they have abnormal cells. If a polyp does become cancerous, the cancer can spread into the lining of the colon or rectum, and eventually through other layers. Once inside the wall of the colon or rectum, the cancer can then spread into the blood vessels and lymph system (nodes) or other, distant parts of the body (metastasis).  A few other, less common colorectal cancers include: Carcinoid Tumors that arise from hormone-producing cells in the colon. Gastrointestinal Stromal Tumors (GISTs) that arise from special cells in the lining of the colon, and which can be either cancerous or non-cancerous (benign); however, GISTs do not commonly appear in the colon. Lymphomas, which are cancers that begin in lymph nodes. Sarcomas, which begin in the blood vessels, muscles, or connective tissues, and rarely appear as colorectal cancers. Colorectal cancer is classified based on the following stages: Stage 0 – Carcinoma in Situ: abnormal cells may be found in the lining (mucosa) of the colon or rectum. Stage I – Cancer has formed in the lining (mucosa) of the colon or rectal wall and has spread to the submucosa (outer layer) or the muscle layer. Stage II (IIA, IIB, IIC) – Cancer has spread through the muscle of the colon or rectum to the outer layer (serosa); Cancer has spread through the outer layer (serosa) to the lining of the abdomen (peritoneum); Cancer has spread through the outer layer (serosa) to other organs. Stage III (IIA, IIIB, IIIC) – Cancer has spread through the mucosa (inner layer), submucosa (outer layer), or muscle layer of colon or rectum, or through the colon or rectal wall to four-to-six lymph nodes; Cancer has spread through the mucosa (inner layer), submucosa (outer layer), or muscle layer of colon or rectum, or through the colon or rectal wall to the mucosa that lines the abdomen (peritoneum) and one-to-three lymph nodes, or four-to six lymph nodes, or seven or more lymph nodes; Cancer has spread to the mucosa lining the abdomen (peritoneum) and four-to six lymph nodes, or seven or more lymph nodes, or to nearby organs. Stage IV (IVA, IVB, IVC) – Cancer has spread to one area or organ not near the colon or rectum, such as liver, lung, ovary, or distant lymph node; Cancer has spread to more than one area or organ, such as liver, lung, ovary, or distant lymph node; Cancer has spread to the lining of the wall of the abdomen (peritoneum) and may have spread to other organs. The level of staging for colorectal cancer determines its treatment and outcomes (prognosis).

Alternative names for colorectal cancer include bowel cancer, cancer of the rectum, colon cancer, gastrointestinal (GI) cancer, gastrointestinal stromal tumors (GISTs), hereditary non-polyposis colorectal cancer (Lynch syndrome), intestinal cancer, and rectal cancer.

Colorectal cancers occur when a cell’s DNA is damaged and mutates and then becomes cancerous, eventually forming tumors. Other than DNA mutations, the causes of colorectal cancer are unknown. However, there are several risk factors that increase the likelihood of developing colorectal cancer, such as having a family history of colon cancer or genetic syndromes, such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome), colorectal polyps, or inflammatory bowel diseases (IBD), such as Crohn’s disease or ulcerative colitis. Eating a diet high in fat or low in fruit and vegetables, or high in processed meats, lack of physical activity (sedentariness), being overweight or obese, alcohol consumption, or smoking, as well as being over the age of 50, African American, having diabetes, having ovarian cancer, or having received radiation therapy increases the risk of colorectal cancer.

Colorectal polyps and cancer may not have any symptoms at first. Signs and symptoms of colorectal cancer include a change in daily bowel habits, such as constipation or diarrhea, blood in the stool, narrow stools, ongoing abdominal discomfort, such as cramps, gas, or pain, a feeling of fullness in the rectum, weakness or fatigue, unexplained weight loss, nausea and vomiting, and bleeding from the rectum.

Colorectal cancer treatments are determined by the area of the cancer, its stage (early-or late- stage), and a patient’s overall health. Usual treatments for colorectal cancer include surgery (resection), radiation therapy, radiofrequency ablation, cryosurgery, chemotherapy, targeted drug therapy, and immunotherapy. Early stage colorectal cancer may be treated with a minimally-invasive surgical approach such as polypectomy, endoscopic mucosal resection, or laparoscopic surgery. Polypectomy – The removal of polyps through a colonoscope, usually done for small cancers. Endoscopic Mucosal Resection – The removal of large polyps through a colonoscope, along with a small portion of the inner lining (mucosa) of the colon. Laparoscopic Surgery – For polyps that cannot be removed with a colonoscope, laparoscopic surgery involves small incisions in the abdomen. In addition to removal of polyps, small portions of nearby lymph nodes may also be removed. Advanced stage colorectal cancer, in which cancer may have grown through the wall of the colon, may be treated with partial colectomy (removal of part of the colon), colostomy (temporary or permanent opening into the abdomen), and lymph node removal. Partial colectomy – Removal of the cancerous portion of the colon, often through laparoscopy, along with margins of normal tissue surrounding the cancer. Colostomy – A colostomy, which can be temporary or permanent, is an opening through the abdomen to the remaining portion of the colon with the placement of a bag that fits over the opening for the elimination of stool. Lymph Node Resection – Removal of lymph nodes surrounding the colorectal cancer. Advanced stage colorectal cancer treatments may include chemotherapy, radiation therapy, radiofrequency ablation, cryosurgery, targeted drug therapy, and immunotherapy. Chemotherapy – Chemotherapy for colorectal cancer uses medications to kill cancer cells and may be given before surgery to decrease the size of a tumor, making it easier to remove. Chemotherapy is more often given after the cancer has been surgically removed, if the cancer is too larger to be removed (unresectable), or if the cancer has spread to lymph nodes, and may be combined with radiation therapy. Radiation Therapy – Radiation therapy for colorectal cancer uses intense, directed X-rays and protons that either reduce the size of the cancer or kill it, can be used to stop cancer pain, and is often combined with chemotherapy. Radiofrequency Ablation – Radiofrequency ablation for colorectal cancer uses tiny electrodes to kill cancer cells. Cryosurgery – Cryosurgery for colorectal cancer freezes the cancerous tissue and destroys it. Targeted Drug Therapy – Targeted drug therapies (biologic or biotherapies) are used for advanced colorectal cancer to target specific characteristics, such as a protein or receptor, on cancer cells to kill the cancer cells, and are usually combined with chemotherapy. A type of targeted therapy for colorectal cancer is monoclonal antibodies: vascular endothelial growth factor (VEGF) inhibitor therapy (bevacizumab and ramucirumab); epidermal growth factor receptor (EGFR) inhibitor therapy (cetuximab and panitumumab); and angiogenesis inhibitors (Ziv-aflibercept and Regorafenib). Immunotherapy – Immunotherapy (immune checkpoint inhibitors) is used for advanced colorectal cancer and works by enlisting the body’s own immune system to attack the cancer cells. Palliative Care – Palliative care for advanced colorectal cancer is supportive care used alongside curative care as well as end-of-life care that seeks to improve the quality of life for individuals with cancer, while relieving pain and other symptoms.

There are various support groups for colorectal cancer: CancerCare - https://www.cancercare.org/support_groups/45-colorectal_cancer_patient_support_group Cancer Support Community - https://www.cancersupportcommunity.org/colorectal-cancer Colorectal Cancer Alliance - https://www.ccalliance.org/patient-family-support/patient-family-support-group-chat

Colorectal cancer is the third most common cause of cancer death in the U.S. However, the death rate from colorectal cancer has been decreasing due to earlier screening and removal of polyps before they become cancerous, discovering the disease in the early stages, and improved treatments. Overall, the outcome (prognosis) depends on the stage of the colorectal cancer (early or advanced), whether the tumor has created a blockage in the colon or rectum or has spread through the colon or rectal wall, whether the cancer has not been completely removed, whether the cancer has reoccurred, and the patient’s overall health. Colorectal cancer may reoccur, spreading beyond the colon or rectum to other parts of the body such as the liver, lungs, or other organs. Certain subtypes of colorectal cancer (signet ring and mucinous) have poorer outcomes (prognoses).

Complications of colorectal cancer may include blockage of the colon (bowel obstruction), development of a second primary colorectal cancer, and cancer recurrence or spread (metastasis) to other parts of the body, such as liver, lungs, and other organs. Colorectal cancer treatment-related complications may also occur, such as chemotherapy-related skin and nail changes, hair loss, nausea and vomiting, and fatigue. Treatment for cancer treatment-related complications is an essential part of cancer care.

If you experience any persistent signs and symptoms of colorectal cancer, such as a change in daily bowel habits, such as constipation or diarrhea, blood in the stool, narrow stools, ongoing abdominal discomfort, such as cramps, gas, or pain, a feeling of fullness in the rectum, weakness or fatigue, unexplained weight loss, nausea and vomiting, and bleeding from the rectum, it is important to see a doctor as soon as possible. Early detection of colorectal cancer can improve its outcome (prognosis).

Colorectal cancer can be prevented through colorectal cancer screening for anyone over 50 years of age or older. Screening can locate precancerous polyps that can be removed before becoming cancerous as well as locate any polyps at an early stage, thus improving treatment outcomes. Surgery may cure colorectal cancer if caught early. If you have a family history of colorectal cancer or have an inflammatory bowel disease (IBD), such as Crohn’s disease or ulcerative colitis, or a genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome), this may mean an increased risk of developing colorectal cancer, and therefore it is important to speak with your doctor about when to start screening and how often. Lifestyle changes, such as diet that includes a variety of fruits, vegetables, and whole grains, avoiding a high-fat diet, drinking alcohol in moderation, or not at all, stopping smoking, exercising 30 minutes most days of the week, and maintaining a healthy weight can reduce the risk of colorectal cancer. Low dose aspirin therapy has been shown to help prevent colorectal cancer in some individuals, however, use of aspirin for this purpose must only be used with a doctor’s recommendation.