Saturday, March 20, 2010

How accurate is the conventional method of screening for Cervical Cancer?

This post is written based upon the observation and personal experience of the author, and not influenced by means of payment or any other form of remuneration by any pharmaceutical companies or parties.
With the discovery of Pap smear more than 50 years ago, death due to cervical cancer has been reduce significantly throughout the years worldwide. With the production of first ever Cancer vaccine back in February 27,2006, it marked  a milestone in the history of medicine where personally I felt its significance is in par with the landing of the first man on moon.
With the second vaccine produced by pharmaceutical giant, GSK, it added on to the arsenal at our disposal in the fight against cervical cancer. However, despite these development over the years, even with the marked reduction of mortality, it makes no difference to the family member and patients who was diagnosed with this killer disease.
Somehow, with the presence of these vaccines, some individuals developed this false sense of security that their immunity against cervical cancer last forever, in actual fact false. These vaccines prevent future infection of HPV(Human Papilloma Virus), but does not cure the already existing HPV.
Though vaccinated, one still needs to be screened annually. Last year alone, I had three patients who has sisters who never missed any of their annual Pap Smear, and each time was told to be normal, unfortunately, 5-6 month later, died of cervical cancer.
Despite the marked reduction of occurrence over the years, it makes no difference to these family members and victims who had succumbed to this killer disease which is currently ranked number 2 as the cause of death among women.
In my previous post, I had wrote on why Cervarix is far superior to Gardasil.

Deciding on getting the vaccination done is by far one of the best decision made in a woman's life. If you have decided to totally avoid from contracting this killer disease, vaccination MUST be followed up with annual Pap smear.
Unfortunately, the conventional Pap smear which most clinics perform have a high incidence of false negative. (when a patient have an early changes in the endocervix, which conventional Pap smear fails to detect, and hence its reports comes back as normal)
Such error is tragic to the victim and their family member.
Error occurs especially when cervical carcinoma arises from the inner part of the cervix, where conventional Pap smear's methodology of sampling is relatively poor, hence yields an inaccurate result, which gives a false sense of security to the unfortunate patient. This form of cervical carcinoma is called cervical adenocarcinoma.

While sampling from carcinoma that arises from the ectocervix as illustrated on the diagram above, cancer arising from the endocervix is not easily detectable.

A conventional Pap Smear kit.

The sampling is done using a wooden spatula which is then smeared on a glass slide, which then "fixed" with a chemical called cytospray which then is then looked at under a light microscope by a pathologist.
This method is proved to have high incidence of false negative due to several factors:-
1.majority of cells not collected
2.Non- representative transfer
3.Clumping and overlapping of cells
4.Obscuring materials
Hence since 1996, an improvised version that lessen the false negatives up to 30% was introduced. It is called Thin Prep Pap Smear.

The Thin Prep Pap Test is a liquid-based pap test that employs a fluid transport medium to preserve cells and an automated process to eliminate debris and distribute a representative portion of cells on a slide in a uniform, even layer. A Thin Prep Pap Test slide is clearer, easier to read, and minimizes obscuring blood, mucus, and non-diagnostic debris, enabling increased accuracy for both manual assessment and computerized assessment of the cells. The Thin Prep Pap Test process improves the quality of the sample, preparing a slide that is more appropriate for diagnostic review.

The additional advantage of Thin Prep Pap Smear is that if there exist any abnormality in the cytology report, the same sample can be sent for HPV DNA testing to determine the subtype of HPV(Human Papilloma Virus), or for further test for sexual transmitted diseases.

Hence ladies, with the availability of an improvised Pap Smear, insist upon it to your doctor that you want this method instead of the conventional Pap smear.

1 comment:

anapeace said...

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