Prevention of Cervical Cancer

Awareness

According to the US National Cancer Institute's 2005 Health Information National Trends survey, only 40% of American women surveyed had heard of human papillomavirus (HPV) infection and only 20% had heard of its link to cervical cancer.[35] In 2008 an estimated 3,870 women in the US will die of cervical cancer, and around 11,000 new cases are expected to be diagnosed.
Screening

The widespread introduction of the Papanicolaou test, or Pap smear for cervical cancer screening has been credited with dramatically reducing the incidence and mortality of cervical cancer in developed countries. Abnormal Pap smear results may suggest the presence of cervical intraepithelial neoplasia (potentially premalignant changes in the cervix) before a cancer has developed, allowing examination and possible preventive treatment. Recommendations for how often a Pap smear should be done vary from once a year to once every five years. The ACS recommends that cervical cancer screening should begin approximately three years after the onset of vaginal intercourse and/or no later than twenty-one years of age. Guidelines vary on how long to continue screening, but well screened women who have not had abnormal smears can stop screening about age 65 (USPSTF) to 70 (ACS). If premalignant disease or cervical cancer is detected early, it can be monitored or treated relatively noninvasively, and without impairing fertility.

Until recently the Pap smear has remained the principal technology for preventing cervical cancer. However, following a rapid review of the published literature, originally commissioned by NICE, liquid based cytology has been incorporated within the UK national screening programme. Although it was probably intended to improve on the accuracy of the Pap test, its main advantage has been to reduce the number of inadequate smears from around 9% to around 1%.This reduces the need to recall women for a further smear.

Automated technologies have been developed with the aim of improving on the interpretation of smears, normally carried out by cytotechnologists. Unfortunately these on the whole have proven less useful; although the more recent reviews suggest that generally they may be no worse than human interpretation.

The HPV test is a newer technique for cervical cancer triage which detects the presence of human papillomavirus infection in the cervix. It is more sensitive than the pap smear (less likely to produce false negative results), but less specific (more likely to produce false positive results) and its role in routine screening is still evolving. Since more than 99% of invasive cervical cancers worldwide contain HPV, some researchers recommend that HPV testing be done together with routine cervical screening. But, given the prevalence of HPV (around 80% infection history among the sexually active population) others suggest that routine HPV testing would cause undue alarm to carriers.

HPV testing can reduce the incidence of grade 2 or 3 cervical intraepithelial neoplasia or cervical cancer detected by subsequent screening tests among women 32–38 years old according to a randomized controlled trial. The relative risk reduction was 41.3%. For patients at similar risk to those in this study (63.0% had CIN 2-3 or cancer), this leads to an absolute risk reduction of 26%. 3.8 patients must be treated for one to benefit (number needed to treat = 3.8). Click here to adjust these results for patients at higher or lower risk of CIN 2-3.

Vaccination
HPV vaccine

Gardasil, licensed and manufactured by Merck & Co. is a vaccine against HPV types 6, 11, 16 & 18. Gardasil is up to 98% effective.[42]. It is now on the market after receiving approval from the US Food and Drug Administration on June 8, 2006.Gardasil has also been approved in the EU.

GlaxoSmithKline has developed a vaccine called Cervarix which has been shown to be 92% effective in preventing HPV strains 16 and 18 and is effective for more than four years.Cervarix has been approved some places and is in approval process elsewhere.

Neither Merck & Co. nor GlaxoSmithKline invented the vaccine. The vaccine's key developmental steps are claimed by the National Cancer Institute in the US, the University of Rochester in New York, Georgetown University in Washington, DC, Dartmouth College in Hanover, NH, and the University of Queensland in Brisbane, Australia. Both Merck & Co. and GlaxoSmithKline have licensed patents from all of these parties.

Together, HPV types 16 and 18 currently cause about 70% of cervical cancer cases. HPV types 6 and 11 cause about 90% of genital wart cases.

HPV vaccines are targeted at girls and women of age 9 to 26 because the vaccine only works if given before infection occurs; therefore, public health workers are targeting girls before they begin having sex. The use of the vaccine in men to prevent genital warts and interrupt transmission to women is initially considered only a secondary market.

The high cost of this vaccine has been a cause for concern. Several countries have or are considering programs to fund HPV vaccination.

Dr. Diane Harper, lead researcher for the HPV vaccines, stated that Gardasil and Cervarix will do little to reduce cervical cancer rates. She also stated that no efficacy trials for children under 15 have been performed.

Condoms

Condoms offer some protection against cervical cancer. Evidence on whether condoms protect against HPV infection is mixed, but they do provide protection against genital warts and the precursors to cervical cancer.They also provide protection against other STDs, such as HIV and Chlamydia, which are associated with greater risks of developing cervical cancer.

Condoms may also be useful in treating potentially precancerous changes in the cervix. Exposure to semen appears to increase the risk of precancerous changes (CIN 3), and use of condoms helps to cause these changes to regress and helps clear HPV. One study suggests that prostaglandin in semen may fuel the growth of cervical and uterine tumours and that affected women may benefit from the use of condoms.
Smoking avoidance
Smoking cessation

Carcinogens from tobacco increase the risk for many cancer types, including cervical cancer, and women who smoke have about double the chance of a non-smoker to develop cervical cancer.

Nutrition

Fruits and vegetables

Higher levels of vegetable consumption were associated with a 54% decrease risk of HPV persistence.Consumption of papaya at least once a week was inversely associated with persistent HPV infection.

Vitamin A

There is weak evidence to suggest a significant deficiency of retinol can increase chances of cervical dysplasia, independently of HPV infection. A small (n~=500) case-control study of a narrow ethnic group (native Americans in New Mexico) assessed serum micro-nutrients as risk factors for cervical dysplasia. Subjects in the lowest serum retinol quartile were at increased risk of CIN I compared with women in the highest quartile.

However, the study population had low overall serum retinol, suggesting deficiency. A study of serum retinol in a well-nourished population reveals that the bottom 20% had serum retinol close to that of the highest levels in this New Mexico sub-population.

Vitamin C

Risk of type-specific, persistent HPV infection was lower among women reporting intake values of vitamin C in the upper quartile compared with those reporting intake in the lowest quartile.

Vitamin E

HPV clearance time was significantly shorter among women with the highest compared with the lowest serum levels of tocopherols, but significant trends in these associations were limited to infections lasting 120 days) was not significantly associated with circulating levels of tocopherols. Results from this investigation support an association of micronutrients with the rapid clearance of incident oncogenic HPV infection of the uterine cervix.

A statistically significantly lower level of alpha-tocopherol was observed in the blood serum of HPV-positive patients with cervical intraepithelial neoplasia. The risk of dysplasia was four times higher for an alpha-tocopherol level <>120 days) was not significantly associated with circulating levels of carotenoids.

The likelihood of clearing an oncogenic HPV infection is significantly higher with increasing levels of lycopenes.[62] A 56% reduction in HPV persistence risk was observed in women with the highest plasma [lycopene] concentrations compared with women with the lowest plasma lycopene concentrations. These data suggests that vegetable consumption and circulating lycopene may be protective against HPV persistence.

CoQ10

Women who had either CIN or cervical cancer had markedly lower levels of CoQ10 in their blood and in their cervical cells than the women who were healthy.