Will a new test improve survival rates for cervical cancer?

According to a paper which appeared recently in the New England Journal of Medicine a DNA test outperformed the Pap smear in reducing deaths from cervical cancer. I asked Adeola Olaitan for her thoughts.

Countries in the developing world have a disproportionately high incidence of cervical cancer mainly to the lack of effective screening. Thus, the efforts of Sankaranarayanan et al. identify a low cost, reproducible and reliable screening method is welcome.

The results are encouraging: In a low-resource setting, a single round of HPV testing was associated with a significant reduction in the numbers of advanced cervical cancers and deaths from cervical cancer.

It must be recognised however that these results were achieved within a strictly regulated study environment.

Before accepting HPV testing as a solution to screening in the developing world, it is important to determine the efficacy of the test in a real world setting. I foresee a number of obstacles.

1. Infrastructure: countries with no culture of cervical screening may encounter difficulty identifying eligible women, inviting them to undergo testing and monitoring response. Screening tests save lives only if a significant proportion of the eligible population is covered. The NHSCSP in this country aims at a minimum 80% coverage.

2. The model tested by the authors requires a second visit for women with positive results. Several screening studies in the developing world have reported a high loss to follow up rate in similar studies. This raises questions about the ethics of screening if women with a positive result cannot be contacted for treatment.

3. Although VIA performed far worse in this study group than has previously been reported, it remains an attractive option, with it's ability to yield an instant result and allow for immediate diagnostic testing and/or treatment.

4. Cost. The authors identify the high cost of this screening technique. Even if the test is made available at a tiered rate for developing countries, there are still hidden costs for laboratory tests, recall and follow up.

On the positive side, this is a mechanised tests that avoids the limitations of individual variability and human error which have long been the limitations of cytology.

Thus on the balance, a reduction in death rate from cervical cancer is good news but more information is required before the wholesale introduction of these tests.