Could the cancer numbers be better explained?

Cristina Roure explained in a post in her blog series "Pantone", an experience that Gerd Gigerenzer, Director of the Max Planck Institute for Human Development in Berlin, wrote in the book "How to know when numbers deceive you", where more than half of the surveyed gynaecologists did not estimate, after seeing published scientific data, what was the probability to have cancer of an asymptomatic woman’s with a positive screening mammogram. In fact the error of most of the colleagues was monumental: they said it was 90% when in fact it was 10%.

In a recent post, I commented on the book of Peter Ubel "Critical Decisions", in which the author showed what the emotional force of numbers was, both for patients and for the doctors. In this certainly worrying line, I want to give you a shred of hope. There are ways to show the numbers in order to reduce the reigning confusion. Many experts are warning us to flee percentages, the ineffable pies and the relative risks, and we have to get used to talking to patients of real numbers, pictograms with people and absolute risks. To make myself understood, I include a couple of graphics from the Harding Center for Risk Literacy, a centre which is in the orbit of Gigerenzer and Max Planck. The first is a pictogram on the evaluation of prevention programs for prostate cancer based on PSA controls and anal touch of the gland.

The status quo bias

I like this JAMA (Volpp 2012) article because it raises the issue of the status quo and this is well-timed because just for now, we are accustomed to the debates on the introduction of new technologies or new drugs, and maybe that's why we’re now starting to evaluate the opportunity of innovation in terms of cost-efficiency or even cost-effectiveness. I’m talking about the $150,000 from the introduction of trastuzumab in metastatic cases of breast cancer per year of life gained, or the $370,000 of the use of erlotinib for advanced cancer of the pancreas cases (Weinstein 2010). But the question of the status quo is: are we wondering about the cost–effectiveness of clinical activities that are undertaken every day, or is that the status quo of having achieved a position in the portfolio of services, puts them at safety from doubts?

To illustrate the status quo, without going in-depth, I chose a couple of examples from the field of preventive activities and a couple more from the supposedly curative care activities.

Example 1 - PSA

Almost all health care assurances, both public and private, offer to men of 50 years of age, the opportunity to get an annual PSA test (Prostate Specific Antigen). It doesn’t seem to be a particularly expensive test, but now the controversy focuses on the disadvantages of early detection, because, according to experts, it’s not clear that this will bring more life to patients, but it does seem however, the resulting overtreatment can cause new problems in their daily life (incontinence, impotence). Expert groups claim to inform the men very well about all this prior to taking the test, but the assurances stubbornly continue to offer the annual PSA in its preventive portfolio without further consideration.

In case you are interested in this issue I offer the link to the U.S. National Cancer Institute.