Chemotherapy in oesophageal cancer

Abstract

Squamous cell carcinoma of the oesophagus exhibits a most striking variation of incidence among different regions in the world. Prevalence rates between the most and least affected areas differ approximately 500-fold (0.4/100.000 for women in Utah (U.S.A.) compared to 170/100.000 in some regions in Iran) (I). Specific areas of high incidence include Iran (Azerbadzjan) and certain regions of the former U.S.S.R. (Kazakhstan and Turkmenistan) towards China, forming the so-called Central Asian Cancer Belt, France (Normandy and Brittany), Kenya, Zimbabwe and South Africa (2). Even within a very short distance, high-risk areas adjoin much lower-risk regions, questioning the influence of environmental factors, such as population, local agriculture, climate, vegetation and geology (3). A variety of risk factors have been identified, notably low consumption of fresh fruit and vegetables, consumption of food contaminated by mycotoxins and nitrosamines, and the consumption of alcohol and tobacco. Nitrosamines are potent carcinogens in laboratory animals (4). Apart from their low levels in food, these compounds can be formed in vivo by an interaction of amines and nitrites. Nitrites have been used in the preservation of meats, but can also be formed from nitrate by bacterial reduction during storage of food (5). The effects of the consumption of alcohol per se, although generally believed to be a major cause of oesophageal cancer in Europe and the U.S.A., are far from clear. Spirits have been found to present a much greater hazard than that resulting from consumption of the same amount of ethanol in the form of wine or beer (6). Another complicating factor is the synergistic effect of tobacco smoking on alcohol-related oesophageal cancer, as simultaneous exposure to alcohol and tobacco is common. Smoking as an independent risk factor has been regarded as both plausible (7) and not convincing (8). It is well established that alcohol consumption can lead to nutritional deficiency, potentially increasing the vulnerability of the oesophagus to carcinogens. Results from a case-controlled study of blacks in Washington, DC, with a high incidence of oesophageal cancer (29/100.000), showed that the least well-nourished individuals had twice the risk of developing oesophageal