The number of patients is rapidly increasing due to aging…second in incidence after thyroid cancer.
In the beginning, most are asymptomatic… the depth of invasion is more important than the size of the lesion.
Red meat, processed meat, obesity, etc. are risk factors… Smoking is absolutely prohibited.
Colon cancer is cancer that occurs in the large intestine, which is responsible for the last digestive function in our body. According to national cancer registration statistics released at the end of last year, colon cancer emerged as the second most common cancer type in Korea after thyroid cancer as of 2021. Most colon cancer patients are elderly. As the proportion of the elderly population rapidly increases, it is predicted that the number of colon cancer patients will continue to increase.
The inner wall of the large intestine is composed of four layers: mucosa, submucosa, muscularis, and serosa. Colon cancer generally occurs in the form of small adenomas in the innermost mucosal layer. It starts out as a small adenoma and gradually grows in size to become a larger adenoma. If it progresses to cancer, it may metastasize to other distant organs. In determining the treatment policy for colon cancer, the depth of cancer invasion is more important than simply the size of the lesion. A condition in which colon cancer grows only to the mucosa or submucosal layer is called early colon cancer. Due to the national five major cancer screening projects and the increase in colonoscopy health checkups, the proportion of early colon cancer is gradually increasing.
Most early-stage colon cancer has no noticeable symptoms. Some colon cancers show small amounts of bleeding intermittently on the surface. This is why, when colon cancer is suspected, a fecal occult blood test is performed first to check for blood in the stool. If blood is detected in a fecal occult blood test, a colonoscopy is performed for an accurate diagnosis.
As a result of colonoscopy, early colon cancer (yellow arrow) is observed. Photo courtesy of Seoul Asan Medical Center
Treatment for early colon cancer can be broadly divided into endoscopic treatment, which is less invasive than surgery, and surgical treatment. Endoscopic resection treatment is a method of removing only early colon cancer itself through colonoscopy. Typically, mucosal resection involves injecting a solution into the submucosal layer to lift the lesion and then cutting the tumor by capturing the lesion using a snare. If the lesion size of early colon cancer is smaller than 2 cm, mucosal resection under colonoscopy can be performed. This endoscopic resection treatment has a limitation in that it cannot remove lymph nodes located outside the colon. If risk factors for metastasis to nearby lymph nodes are identified as a result of a biopsy, additional surgery is required. In fact, one in 10 patients with early colon cancer who received endoscopic resection treatment can be confirmed to have cancer cells that have spread to nearby lymph nodes.
Even if colon cancer is discovered relatively early, treatment methods vary if the size of the lesion exceeds 2 cm. When colon cancer lesions are spread widely before and after or when fibrosis is expected under the lesion, submucosal dissection is performed, which involves peeling off the submucosa using a special knife. If the location of the lesion is judged to be unsuitable for endoscopic resection, surgical treatment may be performed from the beginning. In addition, if the size of the colon cancer lesion is too large and the risk of perforation is judged to be high, or if deep submucosal invasion is suspected, surgical treatment may be considered as a priority. In this way, the optimal treatment is determined by comprehensively considering the lesion pattern, cancer depth, and risk of complications.
To prevent colon cancer, a balanced diet is more important than anything else. A clear correlation has not yet been revealed regarding dietary factors that affect the development of colon cancer. In addition to red meat, consumption of refined carbohydrates such as animal fat, processed meat, alcohol, and sugar, as well as obesity, are considered major causes of colon cancer. On the other hand, dietary fiber consumed from fresh fruits and vegetables plays a role in preventing colon cancer, and sour fruits, dark green vegetables, and dried beans are also known to have a colon cancer prevention effect. Among the general public, there are people who extremely limit their intake of red meat, such as pork and beef, out of fear of developing colon cancer. The problem is that there are conflicting research results that show that consuming only dietary fiber and vegetables without consuming red meat actually increases the incidence of colon cancer. Rather than severely restricting certain foods, we recommend eating a variety of foods in appropriate amounts. Smoking is a risk factor for all cancers. If you currently smoke, it is important to quit smoking.
The earlier colon cancer is detected, the higher the treatment success rate. The most accurate test method to diagnose colon cancer, including early colon cancer, is colonoscopy. In particular, if you have a family history of colon cancer or have risk factors for colon cancer such as smoking or obesity, you should undergo regular colonoscopy.
Seungwook Hong, Professor of Gastroenterology, Asan Medical Center, Seoul
