Impact of HPV Vaccination in Reducing Cervical Cancer: Too Early to Comment?

Researchers demonstrated a reduction in high-grade cervical lesions following the introduction of the HPV vaccine especially in the age group of 18 to 20 years. This good news was published in Cancer. While the credit for this change could go to the HPV vaccine, researchers also believe that it could be due to the changes in screening recommendations for cervical cancer.

Human papilloma virus (HPV) infection is strongly associated with the development of cancer of the cervix in females. There are several cancer-causing HPV strains. Vaccination against the virus could play a role in the prevention of cervical cancer. Currently, HPV vaccine is available as Gardasil^®, Gardasil 9^® and Cervarix^®. Three doses of vaccines are advised in adolescent girls around the ages of 11 to 12 years, with the second dose given 1 to 2 months after the first dose and the third dose about 6 months after the first dose. Some countries including Britain have approved the use of only 2 doses of the vaccine.

Researchers from the HPV-IMPACT Working Group evaluated the impact of the HPV vaccine in preventing cervical cancer. They found that the rate of high-grade cervical lesions which often progress to cancer (cervical intraepithelial neoplasia grade 2, 3, and adenocarcinoma in situ) had reduced in the period between 2008 to 2012 in several cities of the United States, which was the time following the introduction of the vaccine. The change was particularly noted in the age groups of 18 to 20 years, and also in the 21 to 29 years group. However, no major change was noted in the age group of 30-39 years.

Though this reduction in the pre-cancerous changes can be attributed to the impact of vaccination, the researchers caution that it could also be due to the low screening rates in the younger age groups during the same post-vaccination period. Currently, screening for cervical cancer is not routinely recommended in girls below the age of 21 years. Consequently, the researchers found a large decrease in screening among the 18 to 20 years age group, with smaller declines in the other age groups.

The US Preventative Task Force currently recommends cervical cancer screening with Pap smear in women aged 21 to 65 every 3 years. If women between the ages of 30 and 65 years want to be screened less frequently, they have the option of choosing a combination of Pap smear and HPV testing, which can be done every 5 years.

Long-term studies are required before one can say for sure that the HPV vaccine does have a significant effect in preventing cervical cancer. These studies also have to consider that the changes in screening recommendations could affect their study results as well.

Source-Medindia