 These bracken-associated tumours might form a model for some types of human oesophageal cancer.Human papillomavirus DNA has been detected in around 18% of squamous cell carcinomas of the oesophagus, and there is an association between exposure to or consumption of bracken (which is used as a foodstuff and herbal remedy in South America, China, Japan, Korea and other countries) and risk of developing oesophageal cancer.BPV-1 and BPV-2 can also induce sarcomas and fibrosarcomas in other mammals, including equids (equine sarcoid) and, experimentally, rabbits, hamsters and mice (and reviewed in).