Malignant intestinal obstruction refers to intestinal obstruction caused by primary or metastatic malignant tumors, and is one of the common complications of gastrointestinal tumors and pelvic tumors in the late stage, with many uncomfortable symptoms, often multiple obstruction sites, little possibility of surgical resection, critical condition, poor prognosis, serious decline in patients’ quality of life, and very difficult treatment.
The causes of MBO can be divided into two categories: cancerous and non-cancerous. The cancerous etiology mainly refers to the obstruction caused by cancer dissemination (common in small bowel obstruction) and primary tumor (common in colon obstruction).
Mechanical intestinal obstruction caused by malignant tumors may be combined with inflammatory edema, constipation, tumor and treatment-induced fibrosis, cachexia or electrolyte disorders (e.g., low potassium), abnormal intestinal dynamics, decreased intestinal secretion, dysbiosis of intestinal flora and adverse drug reactions, which further complicate and worsen the condition.
Non-cancerous causes include intestinal adhesions, intestinal stricture and intra-abdominal hernia after surgery or radiotherapy, and fecal impaction in elderly and frail patients. The incidence of MBO due to non-cancerous causes accounts for about 3% – 48% of MBO.
Even in patients with MBO with known malignant lesions, the possibility of non-cancerous causes of MBO should be considered.
The pathological types of malignant intestinal obstruction include two major categories: mechanical intestinal obstruction and functional intestinal obstruction.
Mechanical intestinal obstruction is the most common type of MBO pathology, which is caused by tumor invasion of the intestine or abdominal cavity! It is caused by narrowing of the intestinal lumen due to tumor invasion of the intestine or abdominal cavity! Its pathological subtypes include: extra-intestinal luminal occupying MBO caused by primary tumors, mesenteric and omental masses, abdominal or pelvic adhesions, fibrosis after radiotherapy, etc.; intestinal luminal occupying MBO caused by polyp-like lesions caused by primary tumors or metastatic carcinomas, intestinal luminal occupying MBO caused by circumferential dissemination of tumors along the intestinal lumen, and intestinal wall occupying MBO. Functional intestinal obstruction: also called dynamic intestinal obstruction, is due to tumor infiltration of mesentery, intestinal It is caused by tumor infiltration of intestinal mesentery, intestinal muscles, abdominal cavity and intestinal plexus, resulting in impaired intestinal motility, as well as paralytic intestinal obstruction caused by paraneoplastic syndrome neuropathy (especially in lung cancer patients), chronic pseudo-intestinal obstruction, paraneoplastic pseudo-intestinal obstruction and neurotoxicity of chemotherapy drugs.
The clinical manifestations of malignant intestinal obstruction are often manifested as follows: most of them have slow onset and long duration, and are often incomplete intestinal obstruction. Common symptoms include nausea, vomiting, abdominal pain, abdominal distension, and loss of bowel movements. The initial symptoms are usually intermittent abdominal pain, nausea, vomiting and abdominal distension that can be spontaneously relieved, and there is usually still defecation or exhaustion during the onset of symptoms. The symptoms progressively deteriorate to persistent obstruction as the disease progresses. In the later stage, the patient’s body temperature rises, the abdominal distension becomes more obvious, the intestinal wall thickens after the dilatation of the intestinal canal, and the exudation increases. The symptoms are related to the location and degree of intestinal obstruction.
The success of treatment for patients with tumor-induced intestinal obstruction is influenced by many factors, such as the degree of obstruction, the type of lesion, the clinical stage and overall prognosis of the tumor, previous and possible future antitumor therapy, and the health and physical status of the patient. Physicians must weigh the advantages and disadvantages of various treatment options and recommend individualized palliative care based on the patient’s prognosis, the biology of the tumor and, most importantly, quality of life.