Colorectal cancer is a malignant tumor of the large intestine. At the initial stage, it is asymptomatic. Subsequently, it is manifested by weakness, malaise, loss of appetite, abdominal pain, dyspepsia, flatulence and intestinal disorders. Intestinal obstruction phenomena are possible. Ulceration of the neoplasm is accompanied by bleeding, but the admixture of blood in the feces with colorectal cancer of the upper intestine may not be visually determined. The diagnosis is made taking into account complaints, anamnesis, examination data, stool test for latent blood, colonoscopy, irrigoscopy, ultrasound and other studies. Treatment – surgery, chemotherapy, radiotherapy.
ICD 10
C18 C19 C20
General information
Colorectal cancer is a group of malignant neoplasms of epithelial origin located in the colon and anal canal. It is one of the most common forms of cancer. It accounts for almost 10% of the total number of diagnosed cases of malignant epithelial tumors worldwide. The prevalence varies greatly in different geographical areas. The highest incidence is detected in the USA, Australia and Western European countries.
Experts often consider colorectal cancer as a “disease of civilization” associated with an increase in life expectancy, insufficient physical activity, eating a large amount of meat products and insufficient fiber. In recent decades, there has been an increase in the incidence in our country. 20 years ago, this disease was on the 6th place in terms of prevalence in patients of both sexes, now it has moved to the 3rd place in men and to the 4th in women. Disease is treated by specialists in the field of clinical oncology, gastroenterology, proctology and abdominal surgery.
Causes
The etiology is not precisely established. Most researchers believe that pathology belongs to the number of polyethological diseases that arise under the influence of various external and internal factors, the main of which are genetic predisposition, the presence of chronic diseases of the large intestine, diet and lifestyle features.
- Errors in the power supply. Modern specialists are increasingly focusing on the role of nutrition in the development of malignant tumors of the colon. It has been found that colorectal cancer is more often diagnosed in people who consume a lot of meat and little fiber. During the digestion of meat products, a large amount of fatty acids is formed in the intestine, which turn into carcinogenic substances.
- Violation of the evacuation function of the intestine. A small amount of fiber and insufficient physical activity lead to a slowdown in intestinal peristalsis. As a result, a large number of carcinogenic agents come into contact with the intestinal wall for a long time, provoking the development of colorectal cancer. The factor aggravating this circumstance is the improper processing of meat, which further increases the amount of carcinogens in food. Smoking and alcohol consumption play a certain role.
- Inflammatory pathology of the intestine. According to statistics, patients with chronic inflammatory diseases of the large intestine suffer from colorectal cancer more often than people who do not have such a pathology. The highest risk is observed in patients with ulcerative colitis and Crohn’s disease. The probability of colorectal cancer directly correlates with the duration of the inflammatory process. With a disease duration of less than 5 years, the probability of malignancy is about 5%, with a duration of more than 20 years – about 50%.
- Intestinal polyps. In patients with colon polyposis, colorectal cancer is detected more often than the population average. Single polyps are reborn in 2-4% of cases, multiple – in 20% of cases, villous – in 40% of cases. The probability of degeneration into colorectal cancer depends not only on the number of polyps, but also on their size. Polyps smaller than 0.5 cm almost never undergo malignancy. The larger the polyp, the higher the risk of malignancy.
Colon cancer often develops in the presence of colorectal cancer and other malignant neoplasms in close relatives. Such cancer is often diagnosed in patients with familial diffuse polyposis, Turco syndrome and Gardner syndrome. Among other predisposing factors indicate:
- age over 50 years
- fatness
- insufficient physical activity
- diabetes mellitus
- lack of calcium
- hypovitaminosis
- immunodeficiency conditions caused by various chronic diseases, weakening of the body and taking certain medications.
Classification
To determine the severity of colorectal cancer, a standard four-stage classification and an international NNM systematization are used, reflecting the prevalence of the primary process, the presence of regional and distant metastases. Depending on the prevailing symptoms , there are four clinical forms of pathology:
- Toxic-anemic form of colorectal cancer. The main symptom is progressive anemia in combination with the so-called “small signs” (weakness, weakness, fatigue) and minor hyperthermia.
- Enterocolitic form of colorectal cancer. Intestinal disorders prevail.
- Dyspeptic form of colorectal cancer. Abdominal pain, weight loss, loss of appetite, belching, nausea and vomiting come to the fore.
- Obturation form of colorectal cancer. Symptoms of intestinal obstruction prevail.
Colorectal cancer symptoms
At stages I-II, the disease may be asymptomatic. Subsequently, the manifestations depend on the localization and features of the growth of the neoplasm. There is weakness, malaise, fatigue, loss of appetite, an unpleasant taste in the mouth, belching, nausea, vomiting, flatulence and a feeling of heaviness in the epigastrium. One of the first signs of colorectal cancer is often abdominal pain, more pronounced with tumors of the left half of the intestine (especially the colon).
Such neoplasms are characterized by stenosing or infiltrative growth, which quickly leads to chronic, and then to acute intestinal obstruction. Pain with intestinal obstruction is sharp, sudden, cramping, recurring after 10-15 minutes. Another manifestation of colorectal cancer, more pronounced when the colon is affected, is intestinal disorders, which can manifest themselves in the form of constipation, diarrhea or alternation of constipation and diarrhea, flatulence.
Colorectal cancer, located in the right part of the large intestine, often grows exophytically and does not create serious obstacles to the advancement of chyme. Constant contact with intestinal contents and insufficient blood supply, due to the inferiority of the vessels of the neoplasm, provoke frequent necrosis with subsequent ulceration and inflammation. With such tumors, hidden blood and pus in the feces are especially often detected. There are signs of intoxication associated with the absorption of the decay products of the neoplasm during their passage through the intestine.
Colorectal cancer of the ampullary rectum is also often ulcerated and inflamed, however, in such cases, impurities of blood and pus in the feces are easily detected visually, and the symptoms of intoxication are less pronounced, since necrotic masses do not have time to be absorbed through the intestinal wall. Unlike hemorrhoids, blood in colorectal cancer appears at the beginning, not at the end of defecation. A typical manifestation of a malignant lesion of the rectum is a feeling of incomplete bowel emptying. With neoplasms of the anal region, pain during defecation and ribbon-like stools are observed.
Anemia may develop due to repeated bleeding. When disease is localized in the right half of the large intestine, signs of anemia often appear already at the initial stage of the disease. The external examination data depends on the location and size of the tumor. Neoplasms of a sufficiently large size, located in the upper parts of the intestine, can be felt by palpation of the abdomen. Colorectal cancer of the rectum is detected during a rectal examination.
Complications
The most common complication of colorectal cancer is bleeding, which occurs in 65-90% of patients. The frequency of bleeding and the volume of blood loss vary greatly. In most cases, there are small recurrent blood losses, gradually leading to the development of iron deficiency anemia. Less often, profuse bleeding occurs with colorectal cancer, posing a threat to the patient’s life. When the left parts of the sigmoid colon are affected, obstructive intestinal obstruction often develops. Another serious complication of colorectal cancer is perforation of the intestinal wall.
Neoplasms of the lower parts of the large intestine can germinate neighboring organs (vagina, bladder). Local inflammation in the area of a low-lying tumor can provoke purulent lesions of the surrounding fiber. Perforation of the intestine in colorectal cancer of the upper intestine entails the development of peritonitis. In advanced cases, a combination of several complications may occur, which significantly increases the risk of surgery.
Diagnostics
The diagnosis is established by an oncologist on the basis of complaints, anamnesis, general and rectal examination data and the results of additional studies. The most accessible screening studies for colorectal cancer are stool analysis for latent blood, rectoromanoscopy (with a low location of the tumor) or colonoscopy (with a high location of the neoplasm). If endoscopic techniques are unavailable, patients with suspected colorectal cancer are referred for irrigoscopy. Given the lower informative value of X-ray contrast studies, especially in the presence of small single tumors, in doubtful cases, irrigoscopy is repeated.
To assess the aggressiveness of local growth of colorectal cancer and to identify distant metastases, chest X-ray, ultrasound of the abdominal cavity, ultrasound of the pelvic organs, cystoscopy, urography, etc. are performed. In difficult cases, with the germination of nearby organs, a patient with colorectal cancer is referred for CT and MRI of internal organs. A general blood test is prescribed to determine the severity of anemia and a biochemical blood test to assess liver dysfunction.
Colorectal cancer treatment
The main method of treating a malignant tumor of this localization is surgical. The scope of the operation is determined by the stage and localization of the neoplasm, the degree of intestinal obstruction, the severity of complications, the general condition and age of the patient. Usually, a segment of the intestine is resected, while simultaneously removing nearby lymph nodes and intestinal fiber. In colorectal cancer of the lower intestine, depending on the localization of the neoplasm, abdominal anal extirpation (removal of the intestine together with the closure device and the imposition of a sigmostomy) or sphincter-preserving resection (removal of the affected part of the intestine with the reduction of the sigmoid colon while maintaining the closure device) is performed.
When colorectal cancer spreads to other parts of the intestine, stomach and abdominal wall, extended operations are performed without distant metastasis. In colorectal cancer complicated by intestinal obstruction and intestinal perforation, two– or three-stage surgical interventions are performed. First, a colostomy is applied. The neoplasm is removed immediately or after a while. The colostomy is closed a few months after the first operation. Prescribe pre- and postoperative chemotherapy and radiotherapy.
Prognosis and prevention
The prognosis depends on the stage of the disease and the severity of complications. The five–year survival rate after radical surgical interventions performed at stage I is about 80%, at stage II – 40-70%, at stage III – 30-50%. With metastasis, the treatment of colorectal cancer is mainly palliative, only 10% of patients manage to reach the five-year survival threshold. The probability of new malignant tumors in patients with colorectal cancer is 15-20%. Preventive measures include examination of patients from risk groups, timely treatment of diseases that can provoke the development of neoplasms.