The sexually transmitted human papillomavirus is the leading cause of oral and pharyngeal cancer incidence in Sweden, MedPage Today reports. A group of scientists from the Karolinska Institute in Stockholm, led by Dr. Torbjörn Ramqvist, studied cases of squamous cell carcinoma of the mouth and pharynx from 1970 and 2007. In analyzing the data, the team estimated the proportion of malignancies in which the presence of DNA was found from papilloma viruses. According to the team’s data, from 1970 to 2002, the share of cancer of the oral cavity and pharynx, as a result of infection with papilloma viruses, increased 3 times from 23% to 68%, and in 2007 it reached 93%. According to the authors of the study, the number of carcinomas of the mouth and pharynx caused by papillomaviruses significantly exceeds the analogous indicator for tumors of the neck and head, i.e. in 45-100% of cases of carcinoma of the mouth and pharynx are due to papillomaviruses. Swedish doctors clarify that the human papilloma virus embeds its DNA in cancer cells, thus increasing the number of neoplasms, similar to cervical and vaginal cancer. According to experts, the growth of cancers caused by papillomaviruses is due to changes in sexual behavior – the increased number of sexual partners and high popularity of oral sex.