Cancer Screening: Little Certainty with Risks (Part 2)

by Wiebke Heiss / MEDICA.de15/06/2009

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

Part 2: Swapping Risks


Also the risks connected to the examinations themselves are often not communicated appropriately: „A colonoscopy is a highly invasive intervention, very uncomfortable and its potential for damage is quite high“, Jørgensen says. According to the Danish scientist people die in very rare cases, for example due to complications arising from an accidental perforation of the intestine. Sometimes bleeding occurs after removing a benign polyp and the sedation during the examination may give rise to complications in elderly people. In Denmark, colonoscopy is not going to be used as a first line screening program because "the evidence on benefits from it is too poor."

Christian Pox confirms that no direct proof from a randomised trial exists for any benefits of this screening. However, the head of department at the Ruhr-University Bochum says that there were many indirect indications. Experts believe that the test for occult blood in the stool decreased the occurrence of colorectal cancer by 30 percent because a positive test result was always followed by a colonoscopy. „If one acts on the assumption that only carcinoma were found with the help of the stool test it should be possible to reduce the cancer rate by 60 to 90 percent with a routine colonoscopy“, the gastroenterologist says, who also is part of the scientific advisory council on preventive colonoscopy.

These theoretical considerations are partly the basis for implementing colonoscopy screening in Germany at the end of 2002. The sceptic Jorgensen, however, points out: „It does not matter which medical intervention we are talking about: It is never sufficient to concentrate solely on the benefits. One always has to consider the risks, too.“ Also Pox points out: „Colonoscopy is a good thing, but it is not perfect.“

No proof for benefits of skin cancer screening

On 1 July 2008, screening for skin cancer was introduced in Germany - the only country in the whole world to do so despite the fact that so far not one controlled randomised study was undertaken to prove a benefit of such a measure. Now any insured over the age of 35 has the right to get their skin examined every two years by a practitioner or dermatologist searching for any suspicious changes. The chairman of the Federal Joint Committee (G-BA), the highest panel in the German public health sector, Rainer Hess recently said in the political magazine Der Spiegel, that the public pressure had been enormous. "Dermatologists had been pointing out the problem for years and the media were willing to stoke fears concerning skin cancer. Against this background, also the willingness of Association of Statutory Health Insurance Physicians increased to support the screening despite small evidence."

Klaus Koch, scientific author of two books that are concerned with the benefits and risks of screenings says: „Fear is being induced in order to ease it again through a screening.“ Data from the US, for example, show that the risk of getting a melanoma is about two percent for men and a little more than one percent for women. The risk to die of it is even smaller than one percent. „Both the threat of contracting a cancer and the benefit of a screening is often overestimated“, Koch says.

Moreover, Koch stresses that the skin cancer screening concentrates on a health problem that is compared to other problems rather small. Indeed, screening for skin cancer may cost public insurances a few hundred million Euros per year since 45 million German citizens are entitled for this examination. A lot of cash for times where money is short. „We should also consider the question how much money is spent on what measure“, Koch says. „The money could ultimately be used for other things.“

The patients' interests, however, are different ones: they want to protect their health and believe that they can decrease their risk of dying of cancer with routine examinations. But Koch raises concerns: „When somebody participates in screening they should be aware of the fact that you may reduce a risk but at the same time enter new risks. You are swapping risks.“ Even though the potential for harm in skin cancer screening is not particularly high, all patients always need to be totally informed about all benefits and most important all risks.

Standards on communication may help here, standards that are to be followed by organisations and doctors. The German Network for Evidence Based Medicine in Berlin - a non-profit organisation for the advancement of public health care in Berlin prepared such criteria last year that should aid in the creation of patient information for examinations in terms of cancer screenings. One of the minimum requirements is: „In order to assess the benefits of a measure, those interested, on one hand, need unbiased information on how high the risk is to contract a specific cancer or to die of it; on the other hand they need information on how high these risks are despite screening.“ Therefore, it may be sensible in the end to decide to participate in a screening program and it may just the same be sensible to decide against it.

Wiebke Heiss/MEDICA.de

- Part 1: Little Certainty with Risks
- Part 2: Swapping Risks