You are here: MEDICA Portal. Part II: Cancer Screening. Cancer.
Little Certainty with Risks (Part 1)
Every year, 140,000 people get skin cancer, it is the most common cancer of all – that is written on the website of a German dermatological association. More than 57,000 Frauen get diagnosed with breast cancer per year, it is the most often occurring malignant tumor in women – that has been published by a German cancer association. The Burda foundation says: Each year, around 73,000 cases of colorectal cancer are being found, about 27,000 people die of it. Anyone confronted with this kind of data will be worried to death.
Therefore, experts, physicians and insurances put a lot of effort into diagnosing any cancer as early as possible by screening the population. They are trying to save lives since the expert world assumes that chances for a cure increase with early detection. However, in order to save as many lives as possible everybody needs to take part in the programs. Institutions and organisations therefore try to motivate the general public with vigorous campaigns into getting a physical examination in certain intervals. Part of these campaigns are numbers that stress a high overall risk of contracting cancer and numbers that stress a great preventive health benefit when taking part in screening programs. The result of the publicity is that most men and women totally overestimate the benefits of screening programs according to Gerd Gigerenzer, director of the Max- Planck- Institute for Educational Research in Berlin.
For many years, the psychologist has been investigating how risks are being communicated in medicine, especially in terms of mammography screenings. In Germany, this program is being covered by public health insurance since the beginning of 2004 for all women from 50 to 69 years. "A lack of transparency prevails in Germany and other countries", Gigerenzer says. Numbers games are part of it: The website of the Federal Ministry of Health, for example, states: „… it is possible to reduce age dependent dying of breast cancer by 20 to 30 percent with introducing a screening-mammography.“ This is not wrong but particularly clever. Because the same data underlying these percentages can also be presented in this way: 4 out of 1000 women die during a time span of ten years without mammography screening, with a screening it is 3 in ten years. If you look at this data in relative numbers the reduction of death cases is indeed 25 percent - from four down to three cases. However, in absolute numbers you save just one woman of a 1000 - that is 0.1 percent.
Results of medical research are being censored
"The great problem in Germany - a democracy - is that the results of medical research are being censored, suppressed or misrepresented. That also happens with screenings", Gigernezer is determined. The reason: The risks every cancer screening program holds are hardly ever being communicated. The Danish scientists Peter Gøtzsche and Margrethe Nielsen have been looking closely at research with more than half a million women in North America and Europe. The results: From 2000 women participating with mammography screening for ten years, ten women will be treated for breast cancer without actually having the condition. On top of that, 200 of those 2000 women will be put through a lot of psychological strain due to a false alarm.
It is these side effects that Karsten Jørgensen from the Nordic Cochrane Centre in Copenhagen is interested in. He is concerned with a phenomenon that becomes more and more apparent in conjunction with screening: over-diagnoses. These are not false-positive results that after a short while will be recognised as not being cancer. „Over-diagnosis means that this cancer would normally never have been detected.“ A screening detects these cases unnecessarily since they would never have been fatal - because the cancer grows too slowly or it would just never have turned into a life-threatening form.
Autopsy studies, for example, revealed that many older men had prostate cancer. „This kind of cancer occurs very often and most men do not die of it“, Jørgensen says. His statement is being backed up by a study recently published in the New England Journal of Medicine: It was found that for every man being saved through a PSA screening, 47 men were diagnosed with prostate cancer that would have never caused problems and would never have influenced their lives. These men too will undergo treatment with a high risk of complications such as impotency or incontinence. „The fact that over-diagnoses do also occur in screenings is less accepted for other cancer forms“, Jørgensen stresses. „However, the fact is also true for those.“
- Part 1: Little Certainty with Risks
- Part 2: Swapping Risks