HPV vaccination and cervical cancer

Cervical cancer is the second most common cancer in women worldwide and it is linked to persistent infection by human papilloma virus (HPV). Vaccination against HPV represents an important tool to obtain a primary prevention of the tumor. There are many strains of the virus but only a small number of them causes cancer. An international team of researchers has recently identified eight strains of the HPV responsible for more than 90% of cervical cancer cases. The study, which was published in the prestigious medical journal The Lancet, examined 60 years of data from 10575 cases of invasive cervical cancer in 38 countries. HPV was found in about 85% of cancer samples.  More than 90% of these cases were caused by  HPV types 16, 18, 45, 33, 31, 51, 58 and 35, in descending order of frequency. Only 1% of cases worldwide were linked to the infection by HPV types 26, 30, 61, 67, 69, 82 and 91. The former group of eight strains will represent the target for the next generation of HPV vaccines. Currently two vaccines are available in the market, Cervarix and Gardasil, which cover the infection by HPV strains 16 and 18. Gardasil covers 11 additional non oncogenic HPV strains which are responsible for genital warts.  Prophilactic efficacy of the two HPV vaccines is almost 100% and they can prevent cancer cases directly linked to infection by HPV strains 16 and 18. Efficacy of the vaccination is obviously dependent upon the recipient not having been already infected with that type of HPV.  Cancer cases due to 16 and 18 HPV strains represent about 60%-70% of total cases. Future efforts will focus on the production of second generation vaccines covering in addition the other six HPV strains (45, 33, 31, 51, 58 and 35) in order to prevent more than 90% of cases.