Sigmoid colon cancer is a malignant neoplasm of epithelial origin located in the sigmoid colon. In the initial stages, it flows asymptomatically. Then there are pains and discomfort in the abdomen, flatulence, a feeling of incomplete bowel movement. There is an alternation of constipation and diarrhea. Often, in the left half of the abdomen, it is possible to feel a tumor-like formation. The diagnosis is made on the basis of complaints, anamnesis, external examination data, ultrasound, rectosigmoscopy, irrigoscopy, MRI, biopsy and other studies. Treatment – surgery, chemotherapy, radiotherapy.
ICD 10
C18.7 Sigmoid colon cancer
Meaning
Sigmoid colon cancer is a fairly common malignant tumor that affects the area of the large intestine located above the rectum. It originates from the cells of the glandular epithelium. It accounts for 34% of the total number of cases of colorectal cancer. In 60% of cases, it affects patients aged 40-60 years. Men suffer 1.5 times more often than women. Initially, disease often proceeds asymptomatically or with little symptoms, which complicates timely diagnosis. With progression, the tumor spreads to nearby organs, gives regional and hematogenous metastases (to the liver, lungs, spine, less often – to other organs). Treatment is carried out by specialists in the field of abdominal oncosurgery and operative proctology.
Causes
The high probability of developing sigmoid colon cancer is due to the peculiarities of this organ. The sigmoid colon is located in the left part of the abdomen, just above the rectum, and has an S-shaped shape. When the progress of the contents through the intestine slows down, the chyme remains in the sigmoid colon for a long time, which increases the contact time of toxic food processing products with the organ mucosa. Sedentary lifestyle and irrational nutrition are considered as factors that increase the risk of developing sigmoid colon cancer: the use of foods with a small amount of vegetable fiber, a large amount of fatty, fried and spicy foods, the predominance of animal fats and light carbohydrates. Both of these factors cause slowing of intestinal peristalsis. Irrational nutrition contributes to an increase in the amount of carcinogenic substances in the intestinal contents.
Among other circumstances that increase the likelihood of pathology, experts call constipation, in which the mucous membrane is not only in contact with carcinogens for a long time, but is also injured by solid contents. Alcohol abuse plays a negative role. In addition, sigmoid colon cancer often develops against the background of precancerous processes and inflammatory bowel diseases. More than 50% of neoplasms occur against the background of intestinal polyps, diverticulitis and other conditions accompanied by damage to the mucous membrane. Unfavorable heredity matters.
Classification
Taking into account the peculiarities of growth, two types of sigmoid colon cancer are distinguished: exophytic and endophytic. Exophytic tumors grow mainly in the intestinal lumen and are protruding nodes on a thick leg. With the progression of the process, the neoplasm often ulcerates, bleeding and infection are possible. Endophytic tumors grow mainly deep into the intestine. They spread along the intestinal wall and can circularly cover the intestine. Areas of ulceration appear in the center of the neoplasm. The circular growth of sigmoid colon cancer causes a narrowing of the intestinal lumen and hinders the movement of feces. The sigmoid colon is more characterized by endophytic tumors.
Taking into account the histological structure , there are three types:
- Adenocarcinoma. It originates from the cells of the glandular epithelium. It is detected in 75-80% of cases of this disease. It can be highly differentiated, moderately differentiated and low-differentiated. The lower the level of differentiation of sigmoid colon cancer, the worse the prognosis.
- Mucosal (mucosal) adenocarcinoma. It is a type of low-grade adenocarcinoma. It is represented by mucinous cells that secrete a large amount of mucus. Rapid growth and early metastasis are characteristic.
- Cricoid-cell cancer of the sigmoid colon. It is represented by atypical ring-shaped cells formed due to intracellular accumulation of mucin, which pushes the cell nuclei to the periphery. It is diagnosed in 3-4% of patients with oncological lesions of the sigmoid colon. It proceeds unfavorably.
Taking into account the prevalence of the process, the following stages of sigmoid colon cancer are distinguished:
- Stage 1 – the size of the tumor does not exceed 2 cm, the node is located within the mucous or submucosal layer. Regional and hematogenous metastases are not detected.
- Stage 2A – the size of the tumor is less than half the length of the circumference of the intestine. Sigmoid colon cancer does not germinate the intestinal wall. Regional and hematogenous metastases are not detected.
- Stage 2B – the tumor affects the intestinal wall, but does not go beyond it. Metastases in lymph nodes are detected. There is no distant metastasis.
- Stage 3A – the diameter of the tumor exceeds half the circumference of the intestine. Metastases are not detected.
- Stage 3B – lymphogenic metastases are detected.
- Stage 4A – sigmoid colon cancer blocks the intestinal lumen. Hematogenous metastases are detected.
- Stage 4B – neoplasm affects nearby organs with the formation of conglomerates, intestinal-vesicular fistulas, etc.
Symptoms
In the early stages, the course of sigmoid colon cancer is asymptomatic or with scant clinical manifestations. Patients may complain of bloating and rumbling in the abdomen, alternating constipation and diarrhea. With progression, there is a predominance of constipation. Impurities of mucus, pus and blood appear in the feces. With the germination of the intestinal wall and the presence of a mechanical obstacle to the advancement of the chyme, cramping or dull pains occur in the left half of the abdomen. Sometimes the first manifestation of the disease is the development of intestinal obstruction.
In patients with sigmoid colon cancer, weakness, fatigue, pallor or grayish skin tone, hyperthermia, weight loss and appetite due to cancer intoxication are detected. With the development of intestinal obstruction, paroxysmal cramping pains occur, recurring every 10-15 minutes, bloating, stools and gas retention are noted. Vomiting is possible. When the intestinal wall is destroyed, peritonitis develops. In advanced cases of sigmoid colon cancer, cachexia, anemia, jaundice and liver enlargement are observed. When hematogenous metastases appear, symptoms indicating a violation of the functions of the affected organs are added.
Diagnostics
The diagnosis of sigmoid colon cancer is made taking into account anamnesis, complaints, objective examination data and the results of additional studies. The most informative are endoscopic methods (rectoromanoscopy and colonoscopy), which allow visually assessing the volume and localization of the tumor, as well as taking material for subsequent histological examination. During the examination of patients with suspected sigmoid colon cancer, irrigoscopy and stool analysis for hidden blood are also used.
Abdominal ultrasound, chest X-ray, spine X-ray and other diagnostic techniques are used to detect metastases. The final diagnosis is made based on the results of histological examination. Sigmoid colon cancer is differentiated with inflammatory and precancerous intestinal diseases, with mobile mesentery tumors and fixed retroperitoneal neoplasms.
Treatment
In the treatment of this pathology, oncologists usually use combination therapy, including surgery, radiotherapy and chemotherapy. At the same time, the leading role is given to surgical treatment aimed at radical removal of the tumor. The amount of surgery depends on the prevalence of sigmoid colon cancer. In the early stages, in some cases, the use of endoscopic techniques is permissible.
In common processes, the sigmoid colon is resected with a mesentery site and nearby lymph nodes. The affected area is removed with 5 centimeters of unchanged distal and proximal intestine. Surgical intervention for sigmoid colon cancer can be one- or two-stage. When performing one-stage operations after the removal of the tumor, the surgeon imposes an anastomosis, restoring the continuity of the intestine. In advanced cases, the intestine is resected with the formation of a colostomy, and the integrity of the intestine is restored a few months after the first operation.
In the pre- and postoperative period, patients with sigmoid colon cancer are prescribed chemotherapy and radiotherapy. In advanced cases, palliative therapy is performed to ensure intestinal patency and reduce pain. Sometimes, with sigmoid colon cancer, emergency surgical interventions are required to eliminate intestinal obstruction, sanitation of the abdominal cavity with peritonitis, etc.
Prognosis and prevention
The prognosis for sigmoid colon cancer is determined by the type of tumor, the prevalence of the malignant process, the level of cell differentiation, the age of the patient, the presence of concomitant diseases and other factors. The average five-year survival rate is 65.2%. With neoplasms of stage 1, 93.2% of patients overcome the five-year milestone. With stage 2 sigmoid colon cancer, 82.5% of patients survive up to five years from the moment of diagnosis. With stage 3 tumors, this indicator decreases to 59.5%, with stage 4 lesions – up to 8.1%.