Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Breast cancer screens scrutinised

19.10.2001


Mammography screening may not stand up to scrutiny.
© SPL


Study questions whether mammography saves lives.

Breast-cancer screening programmes may not save lives, according to a new examination of clinical trials. The controversial findings have led to calls for a re-evaluation of the routine monitoring procedure undergone by numerous women.

Mammography, X-ray breast imaging, is used in Europe and the United States to catch cancers early. "We’ve based a national screening programme on a set of results which do not stand up to scrutiny," says Richard Horton, editor of The Lancet, the medical journal that today publishes the peer-reviewed research.



In January 2000, Ole Olsen and Peter Gotzsche of the Nordic Cochrane Centre in Copenhagen, Denmark first questioned whether regular screening of middle-aged women reduces the overall cancer death rate1. Their challenging re-analysis of large-scale mammography trials sparked public and medical controversy as some questioned the validity of the work.

Now Olsen and Gotzsche have confirmed their earlier conclusions with a more comprehensive analysis2,3. The report comes with further scientific backing from the respected Cochrane Collaboration, an independent, international body that supports high-quality, systematic reviews of health-care treatments. "The best evidence says there is no reduction in mortality following screening," says Olsen.

Horton thinks that the "storm of protest" triggered by the initial report was understandable but subjective. "Everyone wants screening mammography to be a great success," he says. We should not be afraid to put medical procedures under the same scrutiny as any political decision, he argues.

"There is an urgency for the data to be re-analysed correctly," says breast-cancer clinician Serge Rozenberg of the Free University of Brussels in Belgium, and for women to be informed of existing doubts over the efficacy of screening. "This is about millions of women," he says; not acting on this study is "unacceptable".

But some still dispute Olsen and Gotzsche’s techniques and findings. "We estimate that screening is saving on average 1,250 lives a year," says Julietta Patnick, National Coordinator of the UK’s National Health Service breast-screening programme, which aims to examine all women over 50 every 3 years.

A bumpy ride

Around 1 in 8 women in the United States and 1 in 11 in Britain will develop breast cancer during their lives. It is the main cause of female cancer deaths in these countries for women under 54.

Mammography detects small changes in breast tissue that may indicate the beginnings of a tumour; results influence how doctors proceed. Treatment usually involves surgery to remove the abnormal tissue or the whole breast, followed by radiotherapy, chemotherapy or hormone therapy.

Olsen and Gotzsche reviewed seven clinical trials carried out since the 1960s in Europe, the United States and Canada, involving half-a-million women. The studies reported an average 30% reduction in mortality.

But the pair report that several studies were flawed, for example because women were not properly assigned at random to groups with or without screening. In the two best trials, Olsen and Gotzsche conclude that screening produced no reduction in overall death rate.

They calculate that in some trials, lives lost for other reasons outweighed the reduction in deaths due to breast cancer. Deaths in a screened group may be less likely to be ascribed to breast cancer, speculates Olsen - deaths may be "relabelled", he says.

Screened women were also more likely to undergo aggressive treatment. Some of this may have been unnecessary, say the authors - some tissue changes are benign or slow-growing and would not put lives at risk. Treatment also creates its own problems - for example, radiotherapy leads to an increased chance of heart disease.

References
  1. Gotzsche, P.C. & Olsen, O. Is screening for breast cancer with mammography justifiable?. The Lancet, 355, 129 - 134, (2000).

  2. Olsen, O. & Gotzsche, P.C. Cochrane review on screening for breast cancer with mammography. The Lancet, 358, 1340 - 1342 , (2001).

  3. Olsen, O. & Gotzsche, P.C.Screening for breast cancer with mammography. Cochrane Library, issue 4, Oxford: Update Software, in press (2001).

HELEN PEARSON | Nature News Service
Further information:
http://www.nature.com/nsu/011025/011025-5.html
http://www.nature.com/nsu/

More articles from Health and Medicine:

nachricht Investigators may unlock mystery of how staph cells dodge the body's immune system
22.09.2017 | Cedars-Sinai Medical Center

nachricht Monitoring the heart's mitochondria to predict cardiac arrest?
21.09.2017 | Boston Children's Hospital

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>