Colon Cancer

Colon cancer refers specifically to cancer of the colon, the part of the large intestine that is not confined in the pelvis. You may have heard it called colorectal cancer because colon cancer shares the same cause and growth pattern as rectal cancer, however colon cancer treatment is slightly different than rectal cancer because of its anatomy. Colon cancer starts in the inner lining (mucosa) of the colon as abnormal cells multiply and grow, often in the form of polyps first. The cancer then grows along and through the wall of the colon and can spread through the lymphatics to other organs in the body. Colon cancer is highly treatable and curable at early stage, and is preventable with some screening tests.

Symptoms of colon cancer

Most symtpoms of colon cancer are related to bleeding from the tumor or obstruction of the flow of stool, and are dependant on the size of the tumor and the segment of colon involved. When cancer is early, you may have no symptom. Bleeding from tumor is of small amount and not noticible in stool initially, but may cause anemia over time which is found as an abnormal blood test. As tumor grows bigger, you may notice blood (bright or dark red, usually mixed in) with stool, change in bowel pattern (constipation or diarrhea, more narrowed stool, etc), feeling more tired than usual due to anemia, abdominal cramps or bloating discomfort. Sharper abdominal pain occurs when more significant blockage of the colon results, or when the tumor grows through the colon wall causing a perforation. In more advanced stage cancer, you may have weight loss, nausea, decreased appetite, generalized weakness.

Diagnosis and treatment of colon cancer

Diagnosis of colon cancer requires a thorough history and physical exam, blood test, and colonoscopy with biopsy. When biopsy confirms colon cancer, imaging test (typically CT scan) is used to determine the cancer stage clinically. If cancer is confined to the colon wall (stage I or II) or had spread only to adjacent lymph nodes (stage III), surgery to remove the segment of colon with the cancer and surrounding lymph nodes is the standard first-line treatment. Dr. Choi typically performs such surgery with laparoscopic (minimally invasive) technique. The healthy ends of the colon is reconnected, unless there is severe blockage of the colon or anticipated problem with healing in the post-operative period, in which case an ostomy may be created (the bowel is brought out to the skin and the fecal waste is eliminated into a bag attached to the skin. The removed colon is examined under the microscope to determine the pathological (true) stage. Chemotherapy is recommended for stage III cancers. For some extensive clinical stage III cancer, or if cancer has already spread remotely to other organs (stage IV/ metastasized, commonly to liver or lung) upon initial diagnosis, upfront chemotherapy is typically offered. Radiation therapy is rarely if ever used. After adequate treatment of the cancer, you will need check up along with blood tests and imaging studies at regular intervals to monitor for cancer recurrence.

Prevention of colon cancer

Often it is not possible to pinpoint the cause of colon cancer. However there are few known risk factors for colon cancer, some of these preventable. Since most colon cancer starts as polyps and most cancer are diagnosed after age 50, getting your first screening colonoscopy at age 45 (the current recommended age) can allow polyp detection and removal before polyp turns into cancer. You may need to have screening colonoscopy at earlier age and at more frequent interval if you are at higher risk of colon cancer, such as family history of colorectal cancer (especially in parents or siblings), multiple cancers in the family, certain genetic syndrome such as Lynch syndrome and Familial Adenomatous Polyposis (FAP), personal history of colorectal polyps, inflammatory bowel disese or other cancer such as breast, uterine or ovarian cancer. Eating a diet high in fiber and low in fat, regular exercise, avoiding cigarette smoking and minimizing alcohol consumption may also be protective.