Oesophageal cancer

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Abstract
Who gets oesophageal cancer?The two main histological types of oesophageal cancer, adenocarcinoma and squamous cell carcinoma (fig 1⇓), have different causes and patterns of incidence.1 Although the incidence of adenocarcinoma has surpassed that of squamous cell carcinoma in many Western countries, squamous cell carcinoma still represents 90% of all oesophageal cancer cases in most Eastern countries. Register based cohort studies have found that the incidence of oesophageal cancer increases with age and the average age of onset is about 65 to 70 years. Generally, men are more affected than women: the striking 7:1 male predominance of oesophageal adenocarcinoma remains unexplained.1 The origins of oesophageal cancer are multifactorial, including interactions among environmental risk exposures and nucleotide polymorphisms of inflammatory and tumour growth promoting pathways. The two main risk factors for oesophageal adenocarcinoma are gastro-oesophageal reflux and obesity.3 Some gene-environment interaction patterns differ between patients with and without reflux.4 Polymorphisms of genes coding for the obesity linked insulin-like growth factor may also be markers of risk.5 The two main risk factors for squamous cell carcinoma of the oesophagus are tobacco smoking and high alcohol consumption, particularly in combination. The 3:1 male predominance is explained by differences in such exposures between the sexes. Infection with the bacterium Helicobacter pylori, which commonly occurs in the gastric mucosa, seems to reduce the risk of oesophageal adenocarcinoma by about half.6 A possible mechanism is that the gastric atrophy that might follow such infection reduces the acidity and volume of the gastric juice, thereby lowering the risk of gastro-oesophageal reflux.7 Use of aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) might decrease the risk of oesophageal cancer. A recent meta-analysis, mainly including case-control studies, showed a 35% decrease in the risk of oesophageal cancer among users of NSAIDs compared with non-users.8 Factors affecting the choice of using NSAIDs, however, constitute a threat to the validity of observational studies, as highlighted in some investigations.8 9View larger version: In this window In a new window Fig 1 (A) Small oesophageal squamous cell carcinoma seen on endoscopy. (B) Large necrotic and bleeding oesophageal adenocarcinoma seen on endoscopy. Used with permission from Dr Edgar Jaramillo