Which of the following statements about carcinogenesis is false ?

human papillomavirus (HPV). Most HPV infections cause no symptoms and resolve spontaneously. In some, they persist and result in was or precancerous lesions. The precancerous lesions increase the risk of cancer of the cervix, vulva, vagina, penis, anus, mouth, or throat. Nearly all cervical cancer is due to HPV with two types, HPV16 and HPV18, accounting for 70% of cases. Between 60 and 90% of the other cancers are also linked to HPV. HPV6 and HPV11 are common causes of genital was and respiratory papillomatosis. HPV infection is caused by a human papillomavirus, a DNA virus from the papillomavirus family, of which over 150 types are known. More than 40 types are transmitted through sexual contact and infect the anus and genitals. Risk factors for persistent HPV infections include early age of first sexual intercourse, multiple paners, smoking, and poor immune function. HPV is typically spread by sustained direct skin-to-skin contact with vaginal and anal sex being the most common methods. Occasionally, it can spread from a mother to her baby during pregnancy. It does not spread common items like toilet seats. People can become infected with more than one type of HPV. HPV only affects humans.