Cervical cancer screening has always been imperfect

Cancer screening is in the news for all the wrong reasons. The CervicalCheck scandal will be added to a rich strand of medical history examining the ways that women have been treated, often poorly, by healthcare systems. Few medical historians will be surprised by a story in which some actors prioritised the reputation of a system over the needs of its patients. The Pap smear, used by CervicalCheck, has its own interesting history. The problem of false negatives is not new, but is part and parcel of the complexity and ambiguity of the test.

According to Monica Casper and Adele Clarke, the Pap smear "has become the most widely used and entrenched cancer-screening technology in the world". The process by which it became so ubiquitous involved a wide range of actors from medical doctors to cancer patients to women activists.

The Pap smear is named after Dr George Papanicolaou, a Greek doctor working at the Cornell University Medical Center in the early 20th century. The smear originated in his research on the reproductive cycle of female guinea pigs around 1917. A swab of cells taken from the cervix and examined under the microscope would suggest where in the oestrus cycle (the cycle of reproductive hormones) the animal was. Papanicolaou also tried the swabbing on his wife and later on staff and patients at a New York City hospital. When viewing the human cervical swabs he noted changes to the cells suggesting cancer and began to develop the idea of using the swab as a screening test for early stages of cervical cancer. It was not until the 1940s that Papanicolaou had demonstrated, to the satisfaction of the medical community, that his test might be an effective way of detecting very early stage cancer or pre-cancer.

Yet obstacles remained. In the first place the test is easy enough to administer but very difficult to read. Samples of more than 100,000 cells, appropriately stained, had to be read by a trained cytologist (an expert on cells) who had to check every cell for signs of cancerous changes. On average, a cytologist spent 5-10 minutes scanning a single sample and had to take breaks to avoid fatigue. Reading the smear was thus expensive and time consuming with many possibilities for human error. Pathologists examined any suspect smears and made a classification that would be communicated to doctor and patient. The classifications for observed cell changes are difficult to define clearly and have changed over time. Despite the cost and complexity, women in the US began to demand the smear be used as a screening tool because of its potential to save lives through early detection.

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Innovators introduced automation to try to reduce costs and improve consistency in reading the smears. One such system is ThinPrep which uses collection of cells in liquid and a computerised imaging system.

Responsibility

One of the interesting aspects of early cervical screening and indeed of early breast cancer screening was its tendency to place responsibility on the woman. Early campaigns in the 1950s encouraged women to get screened and to pay attention to symptoms but also appeared to place blame on women whose cancers were detected at a late stage. There was an underlying message that if women simply got themselves diagnosed early enough then medical science could cure them. Being past the stage of a cure was the woman’s fault, not the doctor’s.

We saw the resurgence of this kind of thinking when reality TV star Jade Goody was diagnosed with terminal cervical cancer (rare in young women). Some of the press suggested that Goody had ignored cervical smears and not attended to signs and symptoms and therefore she was partly at fault for her advanced stage cancer.

No one has suggested that the victims of the CervicalCheck scandal are at fault. However, there seems to me to be a similar underlying mistrust of women at work. Screening is imperfect and women should be trusted to understand that. Further, when mistakes are made they should also be trusted with that information. We cannot be expected to have trust in healthcare systems that do not have trust in us.

Dr Juliana Adelman lectures in history at Dublin City University