Colon cancer is the third most prevalent malignant tumor in our country, with the incidence rate of colon cancer accounting for about 50% and about 200,000 cases per year. Generally speaking, the prognosis of colon cancer is relatively good and the treatment is basically the same in general, but clinically it is also found that the prognosis and treatment of right hemicolectomy and left hemicolectomy are somewhat different, which are clinically divided into two types according to the different sites of colon cancer: left hemicolectomy and right hemicolectomy. However, it is difficult for patients to distinguish between these two types of tumor diseases, and misdiagnosis often occurs. In order to avoid this situation from happening again, we need to have a comprehensive understanding of the differences between left hemicolectasis and right hemicolectasis, and only based on these can we achieve targeted treatment and eliminate hidden diseases. So, what is the difference between left and right colon cancer? 1.Difference from rupture and bleeding To effectively distinguish left colon cancer from right colon cancer, we can start from the symptoms of rupture and bleeding. Generally speaking, left hemicolectomized colon cancer seldom appears to break down and bleed, and even if it bleeds, it is only a small amount and not obvious. On the other hand, right hemi-colon cancer is prone to ulceration and bleeding, and it is mostly manifested as dark red or sauce-colored stool. 2.Differentiation by touching lumps Usually, left hemicolectomy cancer is not easy to touch lumps, while right hemicolectomy cancer lumps are more obvious, and about 80% of patients can touch lumps. 3.Differentiation from intestinal obstruction Left hemicolectomy is prone to intestinal obstruction, mainly because the lumen of the left hemicolectomy is thin and easy to be blocked, causing obstruction. Right hemicolectomy is less prone to intestinal obstruction, but most of them are prone to secondary infections, such as fever, emaciation, weakness, loss of appetite, etc. 4.Differentiation from the phenomenon of malignant fluid The phenomenon of malignant fluid in left hemi-colon cancer is not obvious and rarely seen. On the other hand, the phenomenon of right hemicolectasis is very common, mainly because right hemicolectasis is easy to break down and bleed secondary to infection, and once the infection is aggravated, toxemia will appear, such as fever, nausea, vomiting, abdominal pain, shortness of breath, etc. These are the four main differences between left hemicolectomy and right hemicolectomy, according to which accurate differentiation and scientific treatment can be achieved. It must be remembered that one should not narrowly think that they are the same type of disease and there is no difference between them, and then blindly treat them, knowing that such a decisive operation treatment method can easily lead to mis-treatment and delay recovery. Only when the type of disease is clear can you get the right treatment to eliminate the disease and restore a healthy life. The colon is “wan” shaped and is divided into two halves by the splenic area in the left upper abdomen. The right half of the colon includes the cecum, ascending colon, and most of the right side of the transverse colon, while the left half of the colon includes the splenic area of the colon, descending colon, and sigmoid colon. The right hemicolectomy is innervated by the superior mesenteric artery, and blood flows back to the superior mesenteric vein, portal vein and into the right lobe of the liver, and its intestinal cavity is wide and thin-walled, and the contents are liquid or semi-liquid. The left hemicolectomy is innervated by the inferior mesenteric artery and emanates from the abdominal aorta a few centimeters below the superior mesenteric artery, and the blood returns to the inferior mesenteric vein, splenic vein, portal vein, and into the left lobe of the liver. The lumen of the left hemicolectomy is narrow, with concentrated stool and semi-solid contents. The tumor is mostly manifested as pus and blood stool, mucus stool, abdominal pain, and unclean stool. Due to the anatomical structure, there are two types of surgery for colon cancer: radical resection of the right hemicolectomy and radical resection of the left hemicolectomy. Generally speaking, the prognosis of left hemicolectomy is better than that of right hemicolectomy. If we look at the stage level, the difference between stage I left and right colon cancer is not much, stage II right colon cancer is a little better than left colon cancer, stage III left colon cancer is significantly better than right colon cancer, why? Right hemicolectomy cancer is mostly seen in women and elderly patients, and their physical condition is mostly worse. In early stage, it is usually polyp-like, and in the middle and late stage, the pathological types are more often low differentiated adenocarcinoma and indolent cell carcinoma, so the prognosis may be worse. On the other hand, left hemicolectomy is mostly seen in men and young people, who may have less underlying disease and better physical condition, and the early stage tumors are more flat and relatively better differentiated. The most important reason for the formation of intestinal cancer is high fat, high protein and low fiber diet, so that the bile acid in the intestine increases, and its metabolite, methylcholanthrene (class I carcinogen) will also increase accordingly, and the exposure of intestinal mucosa of the right hemicolectomy to methylcholanthrene is 10 times more than that of the left hemicolectomy. Therefore, there are significantly more mutation sites in the right hemicolectomy than in the left, which is also an important reason for the poor prognosis of the right hemicolectomy. In terms of adjuvant chemotherapy after surgery alone, there is no difference in the choice of treatment plan for right and left hemi colon cancer, but if the patient’s disease progresses or distant metastasis occurs, it is necessary to choose different treatment plans by combining the expression status of genes such as RAS and BRAF in left and right hemi sites and tumor tissues. The genes commonly used in bowel cancer are KRAS, NRAS, BRAF gene and mismatch repair gene, and the right hemicolectomy is mostly mutated type. Cetuximab can also be considered if it is wild type. The left hemicolectomy gene is often wild type, and chemotherapy combined with Cetuximab or Bevacor is recommended. However, mismatch repair gene mutations (microsatellite instability with high expression) in right hemi-colon cancer have a better prognosis, which is probably the reason why stage II right hemi-colon cancer is better than left hemi-colon cancer, and immunotherapy can also be considered. In the last two or three decades, more and more doctors have recognized the differences between right hemicolectomy and left hemicolectomy, and the treatment has become more and more precise.