Relationships between Alternaria alternata and oesophageal cancer

Although it is uncertain whether fungi can produce the mycotoxins that induce oesophageal cancer, the tumorigenicity of fungi isolated from grain in an area of high incidence of oesophageal cancer has been confirmed. Alternaria alternata is a fungus of importance in this respect. The contamination rate with A. alternata in corn from areas of high morbidity from oesophageal cancer is higher than that in low-morbidity areas. Extracts of A. alternata induced reverse mutation in Escherichia coli, unscheduled DNA synthesis in cultured human amnion FL cells, chromosomal aberrations and sister chromatid exchange in human peripheral blood lymphocytes, mutation in V79 cells and transformation of NIH3T3 cells. Alternariol methyl ether, which is an active compound produced by this fungus, also induced transformation of NIH3T3 cells, and the transformed cells grew in soft agar and were tumorigenic in nude mice. Food mildewed by this fungus induced forestomach tumours in rats. Thus, (i) A. alternata is tumorigenic, (ii) it has been isolated from corn in an area of high incidence of oesophageal cancer, and (iii) contamination with A. alternata in the area of high incidence is higher than that in the area of low incidence. We therefore believe that A. alternata is one of the causes of human oesophageal cancer.