I. Pathogenesis
The esophagus is a muscular food passage between the pharynx and the stomach. The upper end of esophagus is continued in the pharynx at the lower edge of the 6th cervical vertebra, descends along the front of the spine and connects to the gastric cardia at the left side of the 11th thoracic vertebra. Esophageal cancer is a malignant tumor with strong geographical distribution, and the incidence rate varies greatly among countries and regions in the world. It is highly prevalent in China, ranking 4th among malignant tumors, with more than 150,000 new cases per year, accounting for more than half of the total number of annual cases in the world. The incidence rates in western countries such as the United States and Europe are significantly lower than those in Asia and Africa. Moreover, even in China, the incidence rates of esophageal cancer in high incidence areas and low incidence areas are tens to hundreds of times different. In conclusion, the epidemiological characteristics of esophageal cancer are: 1. There are obvious geographical and population distribution, mainly in Henan, Hebei and Shanxi provinces in Taihang Mountains, the junction area of E and Wan in Dabie Mountains, Sichuan Basin and northwest Sichuan, northern Jiangsu Province, the junction area of Fujian and Guangdong, and the Kazakh settlement in Xinjiang. 2. The incidence rate is highest in the center of the high incidence area of esophageal cancer and decreases in a gradient around. 3. The incidence of esophageal cancer is higher in poor areas than in rich areas, and higher in rural than in urban areas.4. The incidence of colored people is higher than that of white people.5. The incidence of esophageal cancer is higher in Asian and African countries than in European and American countries.6. The incidence of esophageal cancer is higher in men than in women, and higher in those with family history than in those without family history.7. Heavy epithelial cell hyperplasia is common in normal people in high incidence areas.8. The incidence of esophageal cancer increases with age (mostly 60-70 years old).
The exact etiology of esophageal cancer is still not fully understood. Most believe that the occurrence of esophageal mucosal epithelial tumors is due to the combined action of multiple factors and long-term chronic stimulation. Dietary characteristics common to people at high risk for esophageal squamous carcinoma development are: eating too fast, overheated food, high starchy food, and little or no vegetables and fruits. Other possible factors include: lack of certain trace elements in soil and food, accumulation of nitrites, lack of vitamins and essential fatty acids due to unreasonable food structure, long-term chronic damage to esophageal mucosa due to various reasons, poor oral hygiene, long-term alcoholism, heavy smoking, long-term consumption of food contaminated with mold (aflatoxin), and genetic factors (24%-61% of esophageal patients in Henan County have family history of esophageal cancer). (24%-61%). Barrett’s esophagus is the most closely related to the occurrence of esophageal adenocarcinoma. Barrett’s esophagus is a phenomenon in which the esophageal squamous epithelium in the esophagogastric junction is repeatedly damaged and healed by gastric reflux, resulting in columnar epithelial hyperplasia. This columnar epithelium is not a congenitally preserved columnar mucosa, but is acquired later and undergoes a process of repeated re-repair. Barrett’s esophagus with severe dysplasia is considered to be a precancerous lesion, closely related to invasive adenocarcinoma, and requires surgical removal.
Most of the esophageal cancers occur in the middle part of the esophagus. The incidence of upper, middle and lower esophageal cancer is 15%, 50% and 35%, respectively. The pathological type is mainly squamous carcinoma, which accounts for about 95%. In recent years, epidemiology shows that squamous carcinoma is still predominant in China, and the incidence rate has a certain decreasing trend. However, the incidence of esophageal cancer in Europe and the United States is on the rise, which is mainly esophageal adenocarcinoma. At present, the proportion of esophageal adenocarcinoma and squamous carcinoma in Europe and the United States is half each. Some people think that the increase of esophageal adenocarcinoma may be related to Barrett’s esophagus and obesity.
Symptoms
Early symptoms of esophageal cancer are atypical, non-specific, sometimes good, sometimes bad and recurrent. Common discomforts include
(1) Choking sensation with large mouthful of solid food. This is the most common early symptom. It usually appears at the first bite of food and disappears later, once every few days to a few months, and can be easily overlooked. In fact, the symptoms can be relieved without taking any medicine because the symptoms are not caused by mechanical obstruction of the disease, but by inflammation of the lesion, nerve reflex, esophageal spasm and other factors. As the disease progresses, the interval between the onset of symptoms is gradually shortened and the symptoms become more pronounced. It is very easy to be misdiagnosed clinically.
(2) Foreign body sensation in the esophagus. About 15-21% of patients feel a foreign body in the esophagus when swallowing. Some patients feel a foreign body adhering to the esophageal wall when eating, and cannot spit out or swallow the discomfort. The site of foreign body sensation is mostly consistent with the site of esophageal lesion.
(3) Pain, discomfort or choking sensation behind the sternum. Mild retrosternal pain occurs after eating or when not eating, sometimes and more easily when eating hot food. Sometimes, the pain may stop at a certain place when swallowing food or may be a mild choking sensation.
(4) Lower segment esophageal cancer may also cause discomfort under the glabella or upper abdomen, eructation and belching.
2.Middle and late stage symptoms
Most of the esophageal cancer patients are already in the middle and late stages when they come to the hospital for consultation. The clinical symptoms of middle and late stage esophageal cancer mainly include
(1) Difficulty in swallowing About 90% of patients come to hospital with this symptom, and the symptom of difficulty in swallowing worsens progressively with time loss. The symptoms appear when eating large pieces of food at the beginning, and gradually develop into requiring boiled water or thin rice to wash down even when eating rice-sized food, and then develop into only being able to eat semi-liquid or liquid diet, and finally dripping water in severe cases. This process usually takes only 3-6 months.
(2) Obstruction In severe cases, there is complete obstruction when eating, often accompanied by persistent spitting of foamy mucus. This is due to the increased secretion of esophageal glands and salivary glands caused by the infiltration and inflammation of esophageal cancer. The accumulation of mucus in the esophagus may lead to reflux, vomiting and even choking, and in severe cases, aspiration pneumonia.
(3) Pain Mostly swallowing pain when eating. In advanced cases, there is persistent retrosternal or back pain, which is dull or vague in nature, but also burning or stabbing pain, and accompanied by a feeling of heaviness. The location of the pain may not coincide with the location of the lesion. The pain often indicates that the tumor has invaded and caused peri-esophagitis or mediastinitis, but it can also be caused by deep ulceration of the esophagus caused by the tumor. If the pain is severe and cannot sleep or accompanied by fever, not only the possibility of surgical resection is small, but also the possibility of tumor perforation should be noted.
(4) Bleeding A few patients with esophageal cancer may also come to hospital for vomiting blood or black stool. The tumor can infiltrate large blood vessels, especially the thoracic aorta, and cause lethal bleeding. In cases with penetrating ulcers, especially those with CT examinations showing tumor invasion of the thoracic aorta, the possibility of bleeding should be noted.
(5) Hoarseness is often caused by direct invasion of tumor or lymph node metastasis in tracheoesophageal groove and compression of laryngeal nerve.
3.Other systemic symptoms, metastatic symptoms and complications
(1) Weight loss and fever. Due to obstruction, food intake decreases, nutrition becomes more and more depressed, wasting and dehydration often appear one after another. Weight loss and fever may also occur when the tumor spreads. Tumor fever mostly occurs in the afternoon, around 38 degrees, and body temperature tends to be normal in the morning and morning.
(2) Tumor infiltration through esophagus invades mediastinum, trachea, bronchus, pulmonary hilum, pericardium, large blood vessels, etc., causing mediastinitis, abscess, pneumonia, lung abscess, tracheobronchial fistula, lethal hemorrhage, etc.
(3) Corresponding symptoms caused by widespread systemic metastasis. For example, in the case of lung metastasis, cough, chest tightness, dyspnea, etc.; in the case of abdominal lymph node metastasis, abdominal pain and loss of appetite, etc. In the case of liver metastasis, right upper abdominal pain, loss of appetite, jaundice, ascites, hemorrhage, coma, etc.
(4) Cachexia, dehydration, and failure. The manifestation is extreme wasting and exhaustion, often accompanied by disorders of hydropower mediators.
III. Physical signs
1.Superficial lymph node enlargement Supraclavicular lymph node enlargement is a common sign of esophageal cancer patients. Both cervical and thoracic esophageal cancers have the possibility of supraclavicular lymph node metastasis. Most of the swollen lymph nodes are very hard, stone-like and fixed. Cervical lymph node metastasis is relatively rare, mainly from cervical and upper thoracic esophageal cancer. Occasionally, there are axillary lymph node metastases. Besides, the probability of superficial lymph node metastasis from other parts is very low.
2.Limited or fixed vocal cord movement If patients have hoarseness, indirect or direct laryngoscopy should be performed to see if there is limited or fixed vocal cord movement. Most of the hoarseness is caused by the enlarged lymph nodes in the tracheoesophageal groove that compress or invade the recurrent laryngeal nerve, or sometimes the tumor may directly invade the recurrent laryngeal nerve.
3.Signs related to metastasis site Tumor metastasis to other parts may show corresponding signs. If there is skeletal pain, find out whether there is local pressure pain in the painful area.
4.General condition Attention should be paid to the general nutritional status of the patient, the presence of fever, anemia and cachexia.
IV. Examination methods
1.Barium X-ray meal examination, also called esophageal film. It is easy, accurate and less painful for patients. It can not only observe the site, length, obstruction, size and depth of ulcer, perforation and fistula formation, but also the change of esophageal mucosa and esophageal dynamics.
2.CT tomography/magnetic resonance imaging (MRI). It can not only see the location and length of the lesion, but also the thickness of esophageal wall, tumor invasion, relationship with adjacent organs, metastasis of cervical or mediastinal lymph nodes and lung metastasis.
3.Esophageal endoluminal ultrasound (EUS). It has a high accuracy of T-stage of lesions, about 70%-80%; meanwhile, the diagnostic rate of metastasis in paraesophageal lymph nodes is also higher than that of CT scan, up to 70% or more.
4.Esophagoscopy and biopsy Esophagoscopy is a more reliable method to diagnose esophageal cancer. It can observe the size, shape and location of the tumor under direct vision, and also biopsy or brush examination on the lesion.
5.Positron emission computed tomography (PET): It can detect primary foci and regional lymph node metastasis, especially has higher sensitivity to distant lymph nodes and distant organ metastasis. This test has been regarded as routine in Europe and the United States.
6.Abdominal CT/B ultrasound: It detects or excludes abdominal metastases.
7.ECT: If bone metastases are suspected, ECT should be performed.
8.Esophageal stretching: If pathology cannot be taken by esophagoscopy, etc., esophageal stretching is another method to obtain cytological diagnosis.
9.Blood routine, liver and kidney function, electrocardiogram, etc. These tests are performed to assess the general condition of the patient and to improve the reference for treatment selection.