Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Breast cancer detected through mammography has survival advantage


Women whose breast cancer was detected by screening mammography had a significantly better prognosis than those whose cancer was found another way - even if the cancer had already spread to their lymph nodes, say researchers at The University of Texas M. D. Anderson Cancer Center who looked at outcomes from randomized screening studies of more than 150,000 women.

A likely reason for that finding is that mammography can detect tumors that are both slower growing and less biologically lethal than those found symptomatically, say the researchers, who published their findings in the Aug. 17 issue of the Journal of the National Cancer Institute.

The study is important because the survival benefit seen in this analysis is much greater than one would expect for screen-detected breast cancer, says the study’s lead author Donald Berry, Ph.D., chair of the Department of Biostatistics and Applied Mathematics. Berry is well-known for his work in designing breast cancer clinical trials sponsored by the National Cancer Institute and for his research in evaluating the effects of screening mammography.

"We know that screening picks up many tumors before they can be detected in other ways and women may benefit from early treatment, but the advantage we found is much larger than what would be expected from the so-called stage shift that is associated with screening mammography," Berry says.

Based on the results, Berry suggests that method of detection should be considered when a treatment plan for newly diagnosed breast cancer is being devised, and that this information also should be collected by researchers conducting clinical trials of experimental therapeutic strategies. "That information may be just as important as other variables, such as the number of positive lymph nodes. If you don’t account for method of detection, the results may not be as accurate as they would be otherwise," Berry says.

"The important message here for clinicians and patients is that breast cancer detected through mammography has a substantially better survival prognosis," he says. "Of two women who have the same age, size of tumors, and similar stage of cancer and spread to lymph nodes, the one whose cancer was detected with mammography has a reason to be happier than the woman whose cancer was detected symptomatically," Berry says.

While that sounds like good news for some patients, Berry says the conclusion should not be over interpreted.

"The paradox is that this result does not mean screening is beneficial," he says. "Without screening, some of the women would not have been diagnosed with breast cancer at all, and in that group, some of them could have avoided surgery and treatment without detriment. The rub is that we don’t know which ones they are."

This issue has long plagued screening mammography, especially when the detected tumors are very small and have not spread. But this study appears to add a new element to the debate, Berry says. "Our conclusions apply generally, and are as important in node-negative breast cancer as they are in node-positive disease," he says.

In this study, researchers examined data from three large randomized breast cancer screening trials - the Health Insurance Plan (HIP) of New York, which assigned about 62,000 women to screening or to a control group; and two Canadian National Breast Cancer Screening Studies (NBSS), which included a total of 44,790 women in the screening groups and 44,961 women in the control groups.

They then looked only at women in these studies who were eventually diagnosed with breast cancer, and adjusted for stage and other tumor characteristics as a way to eliminate what is known as "lead-time bias." Lead time is the time between when the tumor was detected by mammography and when the tumor would have been detected in the absence of screening. Lead-time bias occurs because lead time is added to the survival time of women detected by mammography but not to women whose tumors are detected clinically, Berry says. "Lead time is an artifact of screening and not necessarily a benefit of screening," he says.

If lead-time bias was responsible for improved survival, and if it was eliminated from the screening mammography group, then those patients should have the same survival, statistically, as women whose cancer was detected outside of mammography, the researchers say.

But that is not what they found.

Instead they discovered that all things being equal, the method of detection was a statistically significant independent predictor of breast cancer survival. After adjusting for stage of disease, patients whose breast tumors were discovered after a previous negative mammography screen had a 53 percent greater risk of death from the cancer than women with screen-detected cancer. Patients in the control group (where no mammography was used) had a 36 percent increased risk of death compared to screened patients.

"What is new here is that we found an effect that is beyond stage shift," Berry says. "All breast oncologists know that tumors detected by mammography have a better survival than tumors detected otherwise because they are smaller and more likely to be node-negative. Our study shows that these patients are even better off than their clinical characteristics suggest."

The difference likely is due to what is called a "length bias" which occurs because screening detects disproportionately more slowly growing tumors, the researchers say. This bias statistically incorporates biological characteristics of the tumors which have not yet been discovered, or cannot yet be easily diagnosed, Berry says."If we were able to get down to the molecular level to assess just the right factors at play in cancer development and progression, that might tell us how lethal a tumor is, but we can’t do that right now."

In the meantime, Berry suggests that information on method of detection should be collected for every clinical trial in order to improve the accuracy of findings, or at least as a way that might account for unexpected results. "I am always surprised that clinical trials of new agents result in better outcomes than expected, and it may just be that screen-detected breast tumors are becoming more common over time," he says.

Nancy Jensen | EurekAlert!
Further information:

More articles from Health and Medicine:

nachricht Advanced analysis of brain structure shape may track progression to Alzheimer's disease
26.10.2016 | Massachusetts General Hospital

nachricht Indian roadside refuse fires produce toxic rainbow
26.10.2016 | Duke University

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: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>