Cervical screening

Cervical screening

A recent cervical cancer screening feature ("Smear Campaign", Pink magazine, The Times, July 21) orchestrated by a private laboratory, claimed that the more expensive liquid-based cytology (LBC) - and not the conventional Pap smear - had received some official approval for detection of infection with Human Papilloma Virus (HPV - which may lead to cervical cancer).

HPV infection was first identified in conventional Pap smears by America's Dr Leopold Koss in the 1960s, and which he initially labelled "koilocytosis", suggesting they were probably due to a viral infection.

In 1977, two almost simultaneous landmark scientific reports from Canada and Milan, confirmed that the Koss "koilocytosis" changes in conventional Pap smears were indeed due to HPV infection. It is therefore untrue that active HPV infection cannot be easily diagnosed by the conventional Pap smear, or that LBC is any better than the conventional Pap smear at picking up this viral infection, as insinuated in this magazine feature.

American reviews of claims that LBC is more accurate at picking up abnormalities than the conventional Pap smear, have not found any significant difference in accuracy between the two methods, nor could they determine whether the increased cost of LBC was justified.

America's Food & Drug Administration (FDA)'s Website on cervical cancer screening still features the conventional Pap smear. One needs to emphasise that the accuracy of both LBC and conventional Pap smear depends almost entirely on the experience of the people examining them, and on the internal quality controls of the laboratory, namely, are the tests examined by only one person, or are they checked by a second person, ideally the pathologist responsible for the service?

Maltese women have also been recently bombarded with scare stories about HPV infections. The huge majority of these are harmless, and the body's immune system eventually gets rid of them. They are common in girls in their teens and twenties, and it's a mistake to over-investigate and over-treat this very young age group.

Some local and overseas private laboratories are pushing for screening women with expensive molecular tests for HPV infection, claiming these should replace the cheap Pap smear as a primary screening tool. The United States Preventive Services Task Force has not found sufficient evidence to recommend routine use of this type of HPV testing as a primary screening test for cervical cancer.

The FDA doesn't recommend molecular HPV tests in women younger than 30.

Furthermore, the conclusion, at an Anglo-American conference on cervical cancer screening I attended last September in Edinburgh, was that HPV testing is helpful but not essential for safe patient management. The medical profession practising privately needs to bear in mind the ethical considerations relating to possible over-investigating and over-treating patients with expensive tests and procedures, particularly so if a laboratory, clinic or hospital might possibly be offering financial incentives to doctors (unknown to patients) to encourage take-up of such private facilities.

(Reference: Adult Preventive Health Care section (2006) in ACP Medicine, a publication of the American College of Physicians: www.acpmedicine.com).

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