In 2008, Harald Zur Hausen received the Nobel Prize in physiology and medicine for showing that two human papilloma viruses, HPV16 and HPV18, were associated with the bulk of cervical cancers, and that some of the genes contained within the viruses were incorporated into the infected host tissue, resulting in carcinogenesis. These carcinogenic strains of HPV cause 70% of cervical cancer and kill an estimated 175,000 women annually.