Sent_en: 2zh Theories have been around since the 1940s that childhood exposure to infection was related to the development of childhood leukaemia — one, like the working theory of the UK study, said that lack of immune challenge was a factor, another that leukaemia developed as a delayed result of some type of infection.
Sent_yy: 自20世纪40年代以来，其中一种理论一直认为儿童接触感染与儿童白血病的发展有关，如英国研究的工作理论，认为缺乏免疫挑战是一个因素，另一种理论认为，白血病是由于某种类型的感染而延迟发展的。