HPV Vaccination as a Mode of Cervical Cancer Prevention in Pakistan.

Abstract

In Pakistan, cervical cancer continues to be a challenge. About 68.6millionwomen over the age of 15 are at risk of developing cervical cancer, with the annual number of cases being over 5,000. Of these, more than 3,000 women lose their lives, making cervical cancer the third leading cause of cancerrelated deaths in women of the reproductive age group in Pakistan. In the country, 88% of cervical cancer cases are due to humanpapillomavirus (HPV) serotypes 16 and 18, as reported by the International Agency for Research on Cancer.1 HPV is a nonenveloped DNA virus belonging to the Papillomaviridae family, with over a hundred different serotypes. Of which, 15 to 20 are oncogenic, with 16 and 18 being the most common. HPV is transmitted via sexual activity. It is found that 75% of all sexually active adults are estimated to be positive for at least one HPV serotype. However, most of these infections have spontaneous resolution with only less than 1% progressing to cancer.2 This progression can be reduced by regular screening via pap smears. The developed world has seen a significant decline in cervical cancer mortality since screening through pap smears introduced to the population. Unfortunately, in developing countries like Pakistan, the uptake of pap smears is very limited, estimated at one instance to be as low as 2%.3 In such circumstances, where pap smears are already difficult to conduct and have low uptake, HPV vaccinations become even more crucial for cervical cancer prevention. Two globally licensed HPV vaccines have been introduced in Pakistan: a quadrivalent vaccine Gardasil (marketed by Merck, Pakistan) and a bivalent vaccine Cervarix (marketed by GlaxoSmithKline, Pakistan). Gardasil is protective against the HPV serotypes 6, 11, 16, and 18, providing protection against both cervical cancer and genital warts. On the other hand, Cervarix is effective against serotypes 16 and 18, thereby protecting only against cervical cancer. It is important to note that both these vaccines work prophylactically and do not have any effect on pre-existing infections.2 Despite their introduction in Pakistan, there is a dearth of awareness regarding these vaccines and a low uptake in the general population. One study done in women of the reproductive age group at a tertiary care center in Karachi estimated the awareness of HPV vaccines to be as low as 20% and their uptake to be less than 10%.4