Carcinoma of the oesophagus is common in certain parts of Asia and Africa. A high incidence is found in the coastal areas of the Caspian Sea, Northern Iran, The Transkei of South Africa, the Soviet Republic of Kazakstan, northern China, and along the coast of southern China. In these regions the incidence of oesophageal carcinoma is 50 to 100-fold higher than the rest of the world: in Hunan province of China, for example, the incidence of oesophageal carcinoma is 185 per 100 000 population. By contrast, oesophageal carcinoma is generally uncommon in America and Europe, with notable exceptions in France and Italy.

Over 80 per cent of oesophageal carcinoma seen in Asian countries is of squamous cell origin, while in Western countries as much as 50 per cent of oesophageal carcinoma is adenocarcinoma. The prevalence of oesophageal diseases such as reflux oesophagitis and Barrett's oesophagus in Western countries (which are considered premalignant lesions), may explain the increased proportion of adenocarcinoma. These conditions are uncommon in Asia.

Although the use of alcohol and tobacco is considered to be the main factor predisposing to squamous cell carcinoma of the oesophagus in the West, additional dietary and environmental factors are probably responsible for the high incidence of oesophageal carcinoma in Asia.

Environmental surveys have incriminated dietary nitrosamine as an important aetiological factor. In areas with a high incidence of oesopheal cancer, high concentrations of nitrosamine have been isolated from preserved food contaminated by fungi such as Geotrium candidum and Fusarium species. Nitrosamine is also found in food and water in regions where the soil is deficient in trace elements such as molybdenum, copper, and zinc. A deficiency of molybdenum, which is a cofactor for nitrate reductase, is seen in northern China where a high incidence of carcinoma of the oesophagus is encountered in both human populations and in livestock. Dietary deficiency of vitamin C, habitual ingestion of hot food, and betel nut chewing are additional risk factors. Patients with other aerodigestive malignancies have an increased incidence of squamous cell carcinoma of the oesophagus; this is presumably because both malignancies involve exposure to similar environmental carcinogens.

Apart from a familial occurrence of the disease in high incidence areas, there is little evidence to support genetic factors playing a role in the pathogenesis of oesophageal carcinoma.

The disease commonly affects men in their 60s and 70s. In Asia, the male to female ratio is 8:1. Macroscopically, the tumour may present as an ulcerative, fungating, infiltrating, or rarely polypoidal or verrucous lesion. Histologically, squamous cell carcinoma accounts for over 80 per cent, of all cancers, 15 per cent being adenocarcinoma. The remainder are rare tumours such as mucoepidermoid, adenoid cystic, oat cell carcinoma, and spindle cell carcinoma. Other malignant variants include melanoma and leiomyosarcoma.

Squamous cell carcinoma spreads by direct infiltration, subepithelial extension, and lymphatic and bloodborne metastasis. Longitudinal subepithelial spread is common, and may be found some distance away from the main tumour. For this reason, a subtotal oesophagectomy should be carried out with an in-vivo 10-cm proximal margin if possible. Anastomotic recurrence after resection is proportional to the length of resection margin; it is estimated that the anastomotic recurrence rates for a 2-cm, 5-cm, and 10-cm margin are 20, 13, and 4 per cent respectively.

The most common presenting symptom is dysphagia, initially for solids and later for liquids as the obstruction becomes complete. However, the dysphagia may not be apparent until more than half of the lumen of the oesophagus has been obliterated. Furthermore, socioeconomic conditions mean that many patients in Asia may not seek medical attention until significant disabling symptoms have arisen. This delay often results in patients having an advanced tumour at the time of presentation. Other symptoms include regurgitation, chest pain, cough, and weight loss. Hoarseness is the result of recurrent laryngeal nerve palsy; the left side is usually affected. General examination may reveal weight loss, muscle wasting, and dehydration. Examination of the chest may show pneumonia, due to aspiration, or the development of a tracheo-oesophageal fistula. There may be cervical lymphadenopathy or hepatomegaly due to metastasis.

In addition to routine tests, specific investigations for oesophageal carcinoma include a chest radiograph, a double-contrast barium study, flexible endoscopy, and bronchoscopy. Chest radiographs may show a hilar mass, tracheal compression and deviation, aspiration pneumonia, or pulmonary metastasis. Additional features which are of importance in assessing operability are pulmonary emphysema and evidence of tuberculosis. The latter is endemic in many parts of Asia.

Barium study will show mucosal irregularity and shouldering, which is diagnostic of the tumour. It also indicates the level and length of the tumour. The features which are suggestive of advanced disease include angulation, sinus formation, and fistulation.

Fibreoptic endoscopy allows histological confirmation of the carcinoma to be obtained on samples obtained by biopsy or brush cytology. Flexible bronchoscopy is performed to assess tumour involvement of the tracheobronchial tree. Signs of involvement include a widened carina, external compression, tumour infiltration, and fistulation: the last two are considered contraindications to resection.

In most parts of Asia, CT or MRI scanning is not readily available and cannot be used routinely for preoperative staging. However, the accuracy of detecting tumour infiltration and lymph node metastasis with CT or MRI scan is only between 50 and 75 per cent. The absence of a fat plane around the oesophagus and the imprecise detection of affected lymph nodes are partly responsible for this low accuracy. Endoscopic ultrasound may provide a more precise preoperative staging than CT or MRI scan. This investigation is possible only if the tumour is not completely obstructing the oesophagus.

Investigation of other causes of dysphagia is less important in Asia as the vast majority of the patients with dysphagia will have oesophageal carcinoma. Benign causes of dysphagia such as oesophageal motility disorders and oesophagitis are uncommon in Asia compared with Western countries. In our experience, simple investigations such as chest radiography, barium study, and endoscopy are adequate for the purpose of diagnosis and preoperative assessment of resectability.

Late presentation is the rule in patients with oesophageal carcinoma. In Asia, about 15 to 25 per cent of patients will have distant metastases at the time of presentation. The primary objective of treatment, therefore, is to relieve the symptoms of dysphagia, as curative treatment is only possible in about 20 per cent of patients.

Various surgical or non-surgical treatments are available for the management of oesophageal carcinoma. Surgical treatment includes resection of the tumour with reconstruction of the oesophagus, or bypass operations for unresectable tumours. Non-surgical treatment includes radiotherapy, chemotherapy, intubation, and laser thermocoagulation.

Most patients in Asian countries are treated surgically: this is the most effective method of relieving dysphagia, and most patients request surgery by the time they present. The type of operation depends on the stage of the tumour and also on the general condition of the patient. However, surgery is associated with a higher morbidity and mortality than is non-operative treatment. The main causes of death after surgery are respiratory complications, malignant cachexia, and sepsis. Only when the surgical risk is reduced to an acceptable level can the choice of surgery as the primary mode of treatment be justified.

Squamous cell carcinoma is generally radiosensitive and theoretically radiocurable. In contrast, radiotherapy for adenocarcinoma is much less effective. Unfortunately, even in Asia where the majority of oesophageal carcinomas are of squamous cell origin, few cures are obtained by radiotherapy alone. As in the West, the 1-year survival is 20 per cent and the 5-year survival is 5 per cent. Palliation of the dysphagia is achieved in under 50 per cent of patients. Failure to alleviate the symptoms is the result of either poor response to radiotherapy, recurrence of tumour, or development of postirradiation stricture.

The value of chemotherapy as primary treatment is unproven. Although there is objective evidence of tumour regression and lengthening of the disease-free period when chemotherapy is used, there is no evidence of improvement in overall survival.

Endoscopic insertion of a prosthesis or thermocoagulation (with Nd:YAG laser or Bicap probe) can be used to re-establish the oesophageal lumen. However, in the presence of advanced disease these methods are associated with a 10 to 15 per cent mortality. Complications include aspiration, fistulation, and perforation of the oesophagus. Palliation is often short-term, and the majority of patients are usually only able to tolerate a soft diet.

For patients who are potentially operable, resection offers restoration of swallowing and a chance of cure. In centres where an active surgical policy is pursued, it is estimated that 75 of every 100 unselected patients presenting with oesophageal carcinoma will be operable. Of these 75 patients, resection will be possible in 85 per cent, bypass in 10 per cent, and 5 per cent will be found not suitable for a definitive operation because of unexpected extensive disease. For those undergoing resection, about one-third will be considered cured, as with complete resection of the tumour and adjacent lymph nodes, without evidence of infiltration, gross lymph node involvement, or metastasis.

The 30-day mortality and hospital mortality in experienced centres are 5 per cent and 15 per cent respectively, for patients undergoing surgical resection. The median survival for curative resection, palliative resection, and the overall median survival are approximately 24 months, 6 months, and 12 months, respectively. The corresponding 5-year survival is 30, 5, and 15 per cent.

For patients with potentially resectable lesions, preoperative adjuvant therapy may be given with the aim of improving survival. Adjuvant chemotherapy with or without radiotherapy has been claimed to produce a response in about 50 per cent of patients, and complete histological regression of the tumour has been achieved in a few patients. However, the response is usually transient and subsequent surgical resection is necessary. Moreover, operative morbidity may be increased when preoperative adjuvant therapy is given, while the improvement of survival is uncertain. Prospective randomized controlled studies are in progress to evaluate the value of preoperative chemotherapy. Preoperative radiotherapy alone has not been shown to improve survival.

Only about 10 per cent of oesophageal tumours arise in the cervical part of the oesophagus. These patients are usually treated by radiotherapy in Western countries. In Asia, surgical resection is preferred, partly because of familiarity with the procedures. Resection requires the removal of the hypopharynx, larynx, and a total oesophagectomy with reconstruction using the stomach or colon anastomosed to the pharynx. A terminal tracheostomy is also constructed. For confined lesions, a free jejunal graft or a tubed muscle flap lined internally with skin from the pectoralis region can be used for reconstruction.

The majority of oesophageal carcinomas in Asia occur in the intrathoracic part of the oesophagus. About 50 per cent occurs in the middle thoracic segment, and 20 per cent in the lower thoracic segment. Almost all of the tumours are squamous cell carcinoma. Resection of the tumour can be difficult because of its close relationship to and often invasion into vital contiguous structures in the mediastinum.

Resection is safest when performed by a thoracotomy. The operation begins with an abdominal phase, in which the stomach is mobilized and its blood supply based on the right gastric and right gastroepiploic arcades. This is followed by a right thoracotomy. The tumour is resected together with the adjacent lymph nodes and thoracic duct. The stomach is then advanced cephalad for reconstruction with the proximal oesophagus at the apex of the pleural cavity. In China, a single left thoracotomy incision is commonly used for both the preparation of the gastric tube and the resection and reconstruction of the oesophagus.

Extended regional lymph node dissection is advocated in Japan in addition to tumour resection. This operation includes a bilateral cervical, thoracic, and abdominal lymph node dissection. However, whether this extensive lymph node clearance improves survival has yet to be demonstrated. Prospective randomized trials are currently under way to evaluate this procedure.

A transhiatal resection may be performed in patients with limited cardiopulmonary reserve who are unfit for thoracotomy. In this procedure, the thoracic part of the oesophagus is mobilized by blunt dissection through the enlarged oesophageal hiatus, with the hand passed into the mediastinum. The mobilized stomach is then delivered to the neck orthotopically and anastomosed to the cervical oesophagus. Careful selection of patients is necessary as this method is associated with substantial morbidity. Complications include excessive bleeding, tumour rupture, tracheal perforation, and recurrent laryngeal nerve injury. The procedure is particularly hazardous for tumours of the middle thoracic oesophagus. Survival following transhiatal resection is no better and may be worse than transthoracic resection. This could be due to less radical tumour and lymph node clearance.

Adenocarcinoma comprises 15 per cent of oesophageal carcinoma in Asia, and oesophagogastrectomy is usually performed. This operation involves removal of part or the whole stomach together with the distal oesophagus, and the reconstruction is usually accomplished in the thorax. Total gastrectomy may be necessary if the tumour involves more than one-third of the stomach. In this situation, the colon or jejunum can be used for replacement.

For the 10 per cent of patients who are unsuitable for resection, a gastric, colon, or jejunal loop bypass can offer good symptomatic relief. The substitute organ is brought to the neck via a retrosternal or subcutaneous tunnel and the anastomosis is performed in the neck. A thoracotomy is not necessary. In contrast to non-surgical treatment, most patients can tolerate a normal diet after a bypass operation. However, these patients suffer major operative morbidity, since they are often poor surgical risks. Careful patient selection is necessary.

Carcinoma of the oesophagus is common in Asia. The majority of tumours are of squamous cell origin and located in the middle third of the oesophagus. As presentation of the symptoms is usually late, the prognosis of patients with symptomatic oesophageal carcinoma remains poor, regardless of the type of treatment given. Surgical resection can adequately restore swallowing and offer cure in some patients.

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