Influence of sexual habits on human papillomavirus infection risk and oral cancer

Certain sexual habits facilitate the oral spread of human papillomavirus (HPV), a virus involved in 70−90% of oropharyngeal cancers. This study aimed to investigate the influence of sexual habits, especially oral sex, on the risk of both HPV infection and oral cancer. We searched the following electronic databases for studies published between 1981 and 2018 on sexual behavior, HPV detection, and oral cancer: PubMed (MEDLINE, Cochrane Library), Web of Science (WoS), and Google Scholar. This meta-analysis included 36 studies involving 10,213 oral cancer patients (7,455 males and 2,758 females) and 52,195 subjects without oral cancer (21,172 males and 31,023 females). The data are expressed as odds ratios (ORs) with their 95% confidence intervals (CIs). The risk factors for oral cancer were first sexual contact before the age of 18 years (OR: 1.98; P < 0.01) and number of oral sex partners (> 5) (OR: 1.68; P < 0.001). There were no significant differences between oral cancer patients and controls regarding oral sex practices (P = 0.53), number of sex partners (P = 0.20), number of couples in sex work (P = 0.61), and number of marriages (P = 0.29). Oral sex increased 1.96 times the probability of HPV infection (P < 0.001). Oral cancer patients who engaged in oral sex practices had a 2.75-fold increased risk of HPV positivity (P < 0.001). Oral sex practices may be an important risk factor for HPV infection and oral cancer.