Cancer screening
Usually when there are complaints about cancer screening in New Zealand it’s people complaining there isn’t enough. The Herald has an interesting example of the opposite, under the headline, “Cervical test switch ‘wrong’“. The ‘switch’ is from looking for actual abnormal cells on screening to just looking for high-risk strains of the virus HPV, which are responsible for nearly all cervical cancer.
Everyone agrees that viral testing is important, and that, all things being equal it is more sensitive. The specialists who are complaining say that the initial screen should look for abnormal cells as well, and only proceed further if they are found. The problem with screening based just on the virus is that it will lead to a bigger increase in repeat screening, biopsy, and treatment, with added inconvenience, risk and expense.
Also, as they say in the NZ Medical Journal
The detection of a sexually transmitted infection rather than a significant cytological abnormality is a major change in the aim of screening. This may reduce screening participation. Any reduction in screening coverage will reduce protection from cervical cancer.
I’m not an expert on cervical screening, so I don’t know the answers, but the issues being raised are the right sort of questions to ask about a change in a successful population screening program.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »