Appendiceal adenocarcinoma

　　The etiology of appendiceal adenocarcinoma is not yet clear. According to its manifestations, it is divided into two types: mucosal type and colonic type.
　　1. Mucosal type:Also known as cystadenocarcinoma, originating from cystadenoma, mostly well-differentiated cells, very similar to ovarian cystadenocarcinoma, prone to rupture and peritoneal dissemination, leading to pseudomyxoma peritonei, and easy to recur after surgery.
　　2. Colonic type:It is a polypoid or ulcerous tumor originating from tubular or tubular villous adenoma, similar to colonic adenocarcinoma, and metastasizes along the lymphatic and hematogenous routes.
　　Appendiceal adenocarcinoma commonly occurs at the root of the appendix, so it is easy to invade the ileocecal region and colon. The main routes of metastasis include: ① Lymphatic route, the most common in the colonic type. Once the tumor invades the submucosa, it is highly likely to metastasize along the mesenteric lymph nodes, ileocecal artery lymph nodes, right hemicolonic artery lymph nodes, and even abdominal aorta lymph nodes. ② Hematogenous metastasis, which can metastasize to the liver along the portal venous system and further to tissues and organs throughout the body. ③ Direct invasion and implantation, which can invade adjacent mesentery, cecum, ureter, and even pelvic and abdominal implantation and metastasis. Mucosal-type adenocarcinoma is prone to this type of metastasis, and during surgery, several to hundreds of gelatinous nodules, as large as eggs and as small as sesame seeds, can be seen, often accompanied by ascites. Colonic-type adenocarcinoma with peritoneal metastasis is mainly mucinous adenocarcinoma, followed by differentiated adenocarcinoma, which often occurs in advanced patients.

　　The complications of appendiceal adenocarcinoma mainly include the following two types:

　　1. Appendiceal perforation

　　Due to the thin wall and narrow lumen of the appendix, along with the obstruction of secretions and tumor invasion, appendiceal perforation is easily complicated. Clinical symptoms may include local peritoneal irritation, which is highly likely to lead to implantation of tumor cells in the peritoneal cavity.

　　2. Intestinal obstruction

　　Cases of mucosal-type adenocarcinoma with peritoneal metastasis may develop mechanical or functional intestinal obstruction due to tumor compression or invasion of the intestinal tract. If not treated actively, patients may die due to intestinal obstruction.

　　The main clinical manifestations of appendiceal adenocarcinoma are right lower quadrant pain or a mass in the right lower quadrant. The tumor can narrow and occlude the root of the appendix, causing secretions in the appendix lumen to be difficult to discharge, leading to mucous accumulation. This can be complicated by infection, increasing intraluminal pressure, and presenting with symptoms similar to appendicitis. After being wrapped by the omentum, it adheres to surrounding tissues to form a mass, which is easily misdiagnosed as an appendiceal abscess preoperatively.
　　Symptoms of consumption may include decreased appetite, fatigue, weight loss, and ascites, which are symptoms of malignant tumors.
　　The perforation rate of appendiceal adenocarcinoma is high, which may be related to the high misdiagnosis rate of the disease. Larger tumors compress the narrow lumen of the proximal part of the appendix, causing the lumen to be blocked, secretions cannot be discharged, and the pressure increases leading to rupture and perforation. It is also not excluded that perforation may occur due to necrosis and disintegration of the tumor invading the colon. Perforation is more likely to lead to postoperative peritoneal implantation and metastasis, and a few patients may present with symptoms of intestinal obstruction.

　　The preoperative diagnosis rate is the key to improving the survival rate of appendiceal adenocarcinoma. And doing this is quite difficult. Mayo Clinic reported a group of patients with appendiceal adenocarcinoma, none of whom were diagnosed before surgery, and only 42% were diagnosed during surgery. Most were found to have the disease only after postoperative pathological examination. Therefore, clinical doctors should be vigilant about the possibility of adenocarcinoma when dealing with appendicitis, and the appendix should be incised during surgery to check for tumors. Frozen section examination should be performed on suspicious cases in a timely manner. Efforts should be made to perform a primary right hemicolectomy for confirmed patients. In addition, for well-differentiated appendiceal adenocarcinoma, postoperative close follow-up is needed to provide timely treatment before the formation of peritoneal pseudomyxoma. Literature reports that 35% to 60% of patients may simultaneously or at different times appear intracolonic or extracolonic tumors, so attention should be paid to preoperative diagnosis to prevent missed diagnosis, exploratory surgery to exclude associated peritoneal tumors, and postoperative follow-up to detect synchronous tumors.

　　Appendiceal adenocarcinoma has no typical clinical symptoms. For patients over 40 years old, if there is a long-term pain in the lower right abdomen or painless mass, and after treatment with anti-inflammatory drugs, the mass does not shrink, or even increases, accompanied by weight loss, anemia, and ascites, or if the wound after appendectomy does not heal and even forms a fistula, it should be suspected as this disease. The systematic examination includes:

　　1, Blood test

　　When complicated with acute appendicitis, there may be an increase in white blood cell count, and when there are systemic consumptive symptoms, the patient may have a decrease in hemoglobin, but it is not specific for the diagnosis of primary appendicitis.

　　2, Histopathological examination

　　Under fiberoptic colonoscopy, take the tumor for pathological examination to make a clear diagnosis.

　　3, Barium enema X-ray

　　It can be seen that the cecum segment presents an extracolic arc-shaped indentation or filling defect, the mucosal folds are disordered or even disappear, and the intestinal wall is rigid.

　　4, Ultrasound examination

　　It can be found that there is a mass-like shadow in the lower right abdomen, with unclear boundaries and low echo, and when the tumor is small, it may only be seen that the vermiform appendix is thickened.

　　5, CT, MRI

　　The examination may find something.

　　6, Fiberoptic colonoscopy

　　Visible extracolic pressure bulging, partial mucosal erosion and edema, and severe cases may be able to touch the tumor.

　　The diet of patients with appendiceal adenocarcinoma is similar to that of other tumor patients, and it is preferable to strengthen nutrition and improve immunity.

　　1, Supply easily digestible and absorbable protein foods such as milk, eggs, fish, and soy products, which can enhance the body's anti-cancer ability. Among them, milk and eggs can improve the disorder of proteins after radiotherapy.

　　2, Consume an appropriate amount of carbohydrates to supplement calories. Patients undergoing high-dose radiotherapy may experience the destruction of sugar metabolism within their bodies, causing a sharp decrease in glycogen, an increase in lactic acid in the blood, and the inability to utilize it; and insufficient insulin function. Therefore, supplementing with glucose is effective, and it is also advisable to eat more sugar-rich foods such as honey, rice, flour, potatoes, etc. to supplement calories.

　　3. Eat more foods with anticancer effects, such as turtle, mushrooms, black fungus, garlic, seaweed, mustard green, and royal jelly, etc.

　　The treatment methods for appendiceal adenocarcinoma are similar to those for colorectal cancer, mainly including comprehensive treatments such as surgery, and chemotherapy can be supplemented.
　　1. Surgical Treatment
　　1. Simple appendectomy:If the tumor is well differentiated, has no lymph node metastasis or invasion of veins, is small in size, and has not invaded the submucosal layer, a simple appendectomy can be performed, but there is still controversy.
　　2. Right hemicolectomy:In the early stage of the disease, even if it only invades the submucosal layer, a right hemicolectomy should also be performed. Patients who have undergone a right hemicolectomy have a higher 5-year survival rate than those who have undergone a simple appendectomy. One-time right hemicolectomy has a better prognosis than a second operation. For suspected cases, careful exploration is required, and frozen section examination during surgery should be performed to achieve radical surgery in one operation. Intraoperative intraperitoneal chemotherapy (using fluorouracil to rinse the peritoneal cavity) can be performed.
　　3. Right hemicolectomy plus bilateral oophorectomy:Appendiceal adenocarcinoma is prone to metastasis and implantation to the ovary. For female patients, exploration should be performed during surgery, and rapid biopsy may be necessary to determine whether it should be resected simultaneously.
　　Postoperative Adjuvant Chemotherapy
　　The standard treatment plan for stage III colorectal cancer and some patients with high-risk factors in stage II is the regimen of oxaliplatin combined with fluorouracil (5-fluorouracil) drugs, which should be continued for 6 months.
　　Treatment of IV Colorectal Cancer
　 　A comprehensive treatment plan mainly based on chemotherapy, including various drugs such as 5-fluorouracil, capecitabine, oxaliplatin, irinotecan, bevacizumab, cetuximab, panitumumab, and others. Common chemotherapy regimens include FOLFOX, XELOX, FOLFIRI, etc. Targeted drug therapy such as bevacizumab, cetuximab, and panitumumab can be combined with chemotherapy as appropriate.
　　Treatment of Peritoneal Implantation
　　The combined use of tumor resection and intraoperative intraperitoneal hyperthermic perfusion chemotherapy has certain efficacy for patients with mucosal adenocarcinoma and peritoneal metastasis.