Saturday 6 January, 2007

The new cervical cancer vaccine

Posted in General Practice, May Su, Medicine, Resources at 17:55 by May Su

Original article by: May Su :: Printer friendly

There has been much in the media recently about the new cervical cancer vaccine, “Gardasil”. The first vaccine was initially produced in the 1990s by a team of researchers in Queensland, headed by Professor Ian Frazer; who received Australian of the Year in 2006 for his work. The vaccine was then marketed by CSL pharmaceuticals and released in 2006. It is a vaccine aimed at preventing infection with the human papilloma virus (HPV), also known as the wart virus.

There is a clear relationship to human papilloma virus (HPV) and the development of cervical cancer (1). There are more than 100 different forms of human papilloma virus (HPV), but not all of them are linked to causation of cervical cancer (2). HPV 16 and 18 are indicated in causing over 70% of cervical cancers detected. The other genotypes linked to developing cervical cancer are types 45 and 31. Types 6 and 11 are linked to the clinical manifestation of genital warts and are low risk for developing cervical cancer.

Infection with high risk HPV is almost always sexually transmitted. There is a high rate of transmission and infection is usually asymptomatic. The usual duration of infection ranges from 8 to 14 months. There is a higher risk of cervical cancer developing with prolonged infection.

The screening program in Australia of 2 yearly Pap smears from the age of sexual activity has been extremely effective in reducing the number of women who develop squamous cell cervical cancer by detecting early abnormal cell changes (3). However there are some forms of cervical cancer such as glandular cervical cancer which are difficult to pick up on screening Pap smear. Hopefully the advent of the new vaccine will help to reduce the number of these cancers occuring.

The vaccine is a recombinant vaccine against the four human papilloma viruses (HPV types 6, 11, 16, 18). There is still the possibility of infection with other oncogenic HPV, therefore pap smears are still required for a vaccinated women. However, the risk of cancer is greatly reduced.

Currently the vaccine is aimed at girls prior to sexual activity. The reason for this is that most studies have been regarding prophylaxis of infection with HPV. There is currently uncertain evidence regarding its use in women who have already been infected with HPV 6, 11, 16 or 18. The other current area of interest is in the use of the vaccine for men who have sex with men (MSM) in preventing anal cancer caused by HPV 16 or 18.

The Australian government has approved of a PBS listing for Gardasil for women aged 9 to 26 years of age, after March 2007. If vaccination is required privately prior to that, the cost is currently $466 (Australian). It is also available to males aged 9 to 15 years of age, although not on the PBS.

Dosage: (5)

Administered intramuscularly as 3 separate 0.5 mL doses at the elected date, 2 and 6 months later.

In clinical studies there has been good efficacy with a dosage regimen of 0, 1 month and 3 months.

Gardasil can be administered concurrently with other vaccinations. Main side effects appear to be pain, swelling or erythema at the injection side, and occasionally fever.

References

(1) Daley, EM. Clinical update on the role of HPV and cervical cancer. Cancer Nurs. 1998 Feb;21(1):31-5.

(2) Screening to Prevent Cervical Cancer: Guidelines for the Management of Asymptomatic Women with Screen Detected Abnormalities. National Health and Medical Research Council (NHMRC). (c) Commonwealth of Australia 2006. [Link]

(3) Cervical Cancer Screening [electronic document]. The Cancer Council New South Wales. Last updated: November 2006 [Link]

(4) Gardasil Product information, CSL Pharmaceuticals

Please read the disclaimer

Advertisements

8 Comments »

  1. karen said,

    my daughter has had her 1st cancer injection and ever since she has been really moody and her period has stopped why is she like this please reply

  2. Michael Tam said,

    This is unrelated to the cervical cancer vaccine. I suggest that you see your regular General Practitioner.

    Regards.

  3. belinda said,

    i have recently had the first injection for the new cervical cancer vaccine ten days later i found out i am pregnant could this be affected by the vaccine

  4. Michael Tam said,

    Firstly: read the disclaimer

    Remember that I am not your regular physician. I do not have all the clinically relevant information. The below is simply my opinion on the limited information that you have provided me.

    Gardasil is classified as a “pregnancy category” B2 substance which means that it is a medication “… that have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.”

    In the existing trials of Gardasil, women who fell pregnant during the vaccination course did not appear to have experienced an increased rate of foetal abnormality or miscarriage. However, those trials were not looking for this specifically. I believe that the recommendation in this setting is to delay the further two doses of Gardasil until after delivery.

    From MIMS prescribing information (1):

    Female rats were given the clinical dose of Gardasil (500 microL) intramuscularly twice (during early gestation and one week postnatal) or four times (five and two weeks prior to mating, during early gestation and one week postnatal). Maternal toxicity or adverse effects on offspring were not observed. High titers of HPV type specific antibodies were detected in maternal blood during gestation, in near term fetal blood and in blood of offspring at weaning and at eleven weeks postnatal, indicative of transplacental and lactational transfer of antibodies (see Use in lactation). The effect of Gardasil administration of vaccine treated males on offspring has not been studied.

    In clinical studies, women underwent urine pregnancy testing prior to administration of each dose of Gardasil. Women who were found to be pregnant before completion of a three dose regimen of Gardasil were instructed to defer completion of their vaccination regimen until resolution of the pregnancy. Such nonstandard regimens resulted in postdose 3 anti-HPV 6, anti-HPV 11, anti-HPV 16 and anti-HPV 18 responses that were comparable to those observed in women who received a standard 0, 2 and 6 month vaccination regimen (see Dosage and Administration).

    During clinical trials, 2,266 women (vaccine = 1,115 versus placebo = 1,151) reported at least one pregnancy. Overall, the proportions of pregnancies with an adverse outcome were comparable in subjects who received Gardasil and subjects who received placebo.

    Further subanalyses were done to evaluate pregnancies with estimated onset within 30 days or more than 30 days from administration of a dose of Gardasil or placebo. For pregnancies with estimated onset within 30 days of vaccination, five cases of congenital anomaly were observed in the group that received Gardasil compared to zero cases of congenital anomaly in the group that received placebo. Conversely, in pregnancies with onset more than 30 days following vaccination, ten cases of congenital anomaly were observed in the group that received Gardasil compared with 16 cases of congenital anomaly in the group that received placebo. The types of anomalies observed were consistent (regardless of when pregnancy occurred in relation to vaccination) with those generally observed in pregnancies in women 16 to 26 years of age.

    Thus, there is no evidence to suggest that administration of Gardasil adversely affects fertility, pregnancy or infant outcomes.

    References
    (1) Human papillomavirus vaccine, recombinant (Gardasil), Merck Sharpe & Dohme (Aust.) Pty Ltd. MIMSOnline. Last updated: 27/7/2007

  5. priscilla said,

    The vaccine is not recommended for pregnant women. There has been limited research looking at vaccine safety for pregnant women and their unborn babies. So far, studies suggest that the vaccine does not cause health problems for pregnant women or their developing child. But more research is still needed. For now, pregnant women should wait until their pregnancy is over before getting the vaccine. If a woman finds out she is pregnant after she has started getting the vaccine series, she should wait until her pregnancy is over before finishing the three-dose series.

  6. --- said,

    i had the vaccine and my period has stopped. is it the vaccine?

  7. cherry said,

    Hi. I just had my third doe last jan 27,2012. When is it safe to be pregnant?must it be six months after my third dose? or 2 months after?

    Greatly appreciated your expertise on this.

    Thank you..


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: