Cervical Cancer Prevention In U.S. Should Focus On Vaccinating Adolescent Girls And Revising Screening Policies

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Cervical Cancer Prevention In U.S. Should Focus On Vaccinating Adolescent

Girls And Revising Screening Policies

Article Date: 24 Aug 2008 - 0:00 PDT

The cost-effectiveness of vaccination in the United States against human

papillomavirus (HPV), a sexually-transmitted virus that causes cervical

cancer, will be optimized by achieving universal vaccine coverage in young

adolescent girls, by targeting initial " catch-up " efforts to vaccinate women

younger than 21 years of age, and by revising current screening policies,

according to an analysis by Harvard School of Public Health (HSPH)

researchers in the August 21, 2008 issue of The New England Journal of

Medicine.

In the U.S. In 2007, cervical cancer developed in more than 11,000 women and

killed 3,600 women. Cervical cancer is caused by infection with high-risk

oncogenic " types of HPV, also associated with other cancers. Worldwide, HPV

types 16 (HPV-16) and 18 (HPV-18) cause approximately 70% of cervical cancer

cases. Vaccines against HPV-16 and HPV-18 appear to be highly efficacious in

preventing HPV-16 and HPV-18 infections and cervical disease in females who

have not previously been infected with these types. The quadrivalent vaccine

currently licensed in the U.S. Also prevents low risk HPV types 6 and 11

(HPV-6 and HPV-11) infections, which are responsible for most genital warts

and juvenile-onset recurrent respiratory papillomatosis (JORRP), a rare but

severe respiratory condition usually diagnosed in infancy that may be

related to a mother's infection with genital warts.

Cervical cancer prevention in the U.S. Has traditionally relied on a

screening program involving frequent cytology (Pap smear) and/or HPV DNA

testing, recommended annually or biennially for sexually-active women. HPV

vaccination raises questions regarding the age at which to vaccinate females

target groups for temporary catch-up programs, and appropriate changes to

screening practices.

Jane Kim, assistant professor of health decision science in the Department

of Health Policy and Management at HSPH, led the study which involved

synthesizing epidemiologic, clinical, and demographic information using

sophisticated computer models that simulate the U.S. Population. The models

were used to predict the health and economic outcomes of HPV vaccination of

preadolescent girls (I.e., 12 years of age) and catch-up vaccination over a

5-year period for girls and women over 12 years of age, in the context of

routine cervical cancer screening; strategies differed in the upper age of

catch-up programs, to ages 18, 21, or 26 years. While the study focused on

the prevention of cervical disease, the investigators also examined the

benefits of the quadrivalent vaccine on genital warts and possible benefits

of averting other HPV-related cancers and JORRP.

A novel part of this study involved examining how uncertain scenarios might

impact the appropriate policies for the U.S., such as the duration of

vaccine protection and whether or not a booster dose will be needed, whether

or not the vaccine will also prevent infections with other HPV types, and

what might occur to rates of cancer if women change their screening

practices after being vaccinated.

Kim and co-author Sue Goldie , professor of health decision science at HSPH,

found that vaccination against HPV-16 and HPV-18 would lead to lower

cervical cancer rates and be economically attractive if high coverage can be

achieved in the most important target group of 12-year-old girls, and if

vaccine protection against infection lasted for at least 20 years. The study

predicted that if most 12-year-old girls were vaccinated, their future

cervical cancer screening could begin somewhat later than currently

recommended and be conducted less frequently (I.e., every 3 to 5 years).

At an additional expense, a catch-up program for girls between 13 and 18

years of age appears to offer benefits and be reasonably cost-effective

compared to other vaccine programs in the U.S. The cost-effectiveness of

extending the catch-up program to 21 years of age is less certain, and

depends on whether the vaccine will eventually be proven to prevent other

cancers caused by HPV-16 and -18. Including women to age 26 was consistently

not cost-effective because the vaccine is quite expensive, but is less

effective in women who are already sexually active. Current CDC

recommendations and a recent CDC summary suggest routine vaccination of

girls aged 11-12 and catch-up vaccination of girls and women aged 13 to 26.

There is no absolute criterion that dictates whether a vaccine or public

health intervention is cost-effective in the U.S.; however, most

policy-makers agree that interventions that have a cost-effectiveness ratio

less than $50,000 per quality-adjusted life year (QALY) gained, a metric

used to describe cost-effectiveness, are very good value for money. While

vaccination of 12-year-old girls was less than this threshold, vaccinating

girls into their mid- to late-20s as part of a catch-up program was not.

Kim and Goldie caution that these results could change if future information

shows that vaccine protection does not last, or if there is an unexpected

increase in other cancer causing HPV types not included in the vaccine.

Kim emphasizes, " Our results are the best prediction we can make with the

information available now, but it will be critical to update the analysis as

we learn more about the long-term vaccine effects. "

An editorial, " Human Papillomavirus Vaccination - Reasons for Caution, " by

Charlotte J. Haug, MD., PhD. Editor in Chief of the Journal of the Norwegian

Medical Association, also appears in this issue of NEJM. A long-term

followup study of HPV vaccination is underway in Norway.

Kim and Goldie also emphasize that it will be important to achieve high

coverage among all 12-year-old girls, and not just a small subset, and to

ensure girls are screened for cervical cancer beginning in their early- to

mid-20s, since HPV types not included in the vaccine can still cause cancer.

From a public health perspective, if women who are at continued risk for HPV

infection and cervical cancer are not regularly screened, and if only some

adolescents have access to the vaccine, cervical cancer rates in the U.S.

may not change. Ensuring U.S. women equal access to both preadolescent

vaccination and adult cervical cancer screening, is imperative.

The analysis was funded by the National Cancer Institute, the Centers for

Disease Control and Prevention, and the American Cancer Society. Similar

work in developing countries was funded by the Bill and Melinda Gates

Foundation.

The article, " Health and economic implications of HPV vaccination in the

United States, " will appear inThe New England Journal of Medicine, August 21

2008, Volume 359, Number 8.

Harvard School of Public Health is dedicated to advancing the public's

health through learning, discovery, and communication. More than 400 faculty

members are engaged in teaching and training the 1,000-plus student body in

a broad spectrum of disciplines crucial to the health and well being of

individuals and populations around the world. Programs and projects range

from the molecular biology of AIDS vaccines to the epidemiology of cancer;

from risk analysis to violence prevention; from maternal and children's

health to quality of care measurement; from health care management to

international health and human rights.

Harvard School of Public Health