Mortality is high both in developed and developing countries.
The presence of HPV in oesophageal malignancies is more common in developing than in developed countries. In agreement, we have detected HPV-16 DNA in oesophageal carcinomas from Brasil. BF contains immunosuppressants and mutagens, and, in addition to causing chromosomal abnormalities and neoplasia in ruminants, it induces different types of cancers in experimental animals. DNA adducts have been found in the upper GI tissue of mice fed bracken extracts or bracken spores. BF is used as human food and as herbal remedy in South America, Japan, China, Korea and other Eastern countries.