There are no stupid questions... 2

Unusually swift response to Mdm Haslinda's letter from the Obstetrical and Gynaecological Society of Singapore:


Saving lives
Have a Pap smear done at least every three years

Letter from Dr Chia Yin Nin Member
and A/Prof Tay Eng Hseon President
Obstetrical and Gynaecological Society of Singapore

The Obstetrical and Gynaecological Society of Singapore (OGSS) thanks Haslinda Shamsudin ("How often should Pap smear be done?", Nov 4) for her support for the cervical cancer awareness campaign.

The Pap test, like any medical test, has its limitation. It has a false negative test rate of as high as 30 per cent. The latter is overcome by regular repeated testing. However, the frequency must be balanced against the cost of testing.

Based on studies, Pap smear screening prevents about 84, 91 and 93 per cent of cervical cancers when performed at five-yearly, three-yearly and yearly intervals respectively. That is, the cost of screening would triple, from three-yearly to yearly screening, to gain an additional advantage of 2 per cent increased benefit.

Therefore, the best balance reported between cost effectiveness and life years saved from cervical cancer is a screening interval of between three and five years.

More importantly, the effectiveness of a national Pap smear screening program to prevent cervical cancer hinges on the percentage of population coverage more so than the interval of screening.

In Singapore and elsewhere, the majority of cervical cancers occur in women who have never been screened or have not been screened within the last five years; additional cases occur in women who do not receive appropriate follow-up after an abnormal Pap.

The OGSS recommends all sexually active women, aged between 20 and 69, to attend regular Pap smear screenings at no more than three years in between screenings.


A very informative reply, and it explains why '[p]olytechnic [sic] doctors... advise their patients that it is sufficient to have it done once in three years'.

But it doesn't answer the question as to why '[g]ynaecologists in private practice and at government hospitals... advise that such screenings be done annually' though, does it?

Or would that be a stupid question?