Saturday, March 19, 2011

Cervical cancer/ Cancer Servik: prevention

Vaccination

Gardasil, is a vaccine against HPV types 6, 11, 16 & 18 which is up to 98% effective.
Cervarix has been shown to be 92% effective in preventing HPV strains 16 and 18 and is effective for more than four years.
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 have also been shown to prevent precursors to some other cancers associated with HPV.

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 vaccines have been shown to be effective for at least 4 to 6 years, and it is believed they will be effective for longer, however the duration of effectiveness and whether a booster will be needed is unknown.

The use of the vaccine in men to prevent genital warts, anal cancer, and interrupt transmission to women or other men 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.

Condoms

Condoms offer some protection against cervical cancer. Evidence on whether condoms protect against HPV infection is mixed, but they may protect 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

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

Nutrition

Fruits and vegetables
Higher levels of vegetable consumption were associated with a 54% decrease risk of HPV persistence.
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.[39]
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. Clearance of persistent HPV infection (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 < 7.95 mumol/l.

Folic acid
Higher folate status was inversely associated with becoming HPV test-positive. Women with higher folate status were significantly less likely to be repeatedly HPV test-positive and more likely to become test-negative. Studies have shown that lower levels of antioxidants coexisting with low levels of folic acid increases the risk of CIN development. Improving folate status in subjects at risk of getting infected or already infected with high-risk HPV may have a beneficial impact in the prevention of cervical cancer.
However, another study showed no relationship between folate status and cervical dysplasia.
Carotenoids
The likelihood of clearing an oncogenic HPV infection is significantly higher with increasing levels of lycopenes. 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

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