Men who have sex with men (MSM) are particularly at risk for conditions associated with HPV types 6, 11, 16, and 18; diseases and cancers that have a higher incidence among MSM include anal intraepithelial neoplasias, anal cancers, and genital warts. Type 16 is also associated with oropharyngeal squamous-cell carcinoma, a form of throat cancer.[40] A 2005 study in San Francisco found that 95% of HIV-infected gay men also had anal HPV infection, of whom 50% had precancerous HPV-caused lesions.