domingo, 6 de abril de 2014

JAMA Review: Stop One-Size-Fits-All Mammography

JAMA Review: Stop One-Size-Fits-All Mammography

JAMA Review: Stop One-Size-Fits-All Mammography

Imaging Societies Respond

Nick Mulcahy
April 02, 2014

A woman's decision to undergo mammography "should be individualized based on patients' risk profiles and preferences," concludes a systematic review of 50 years of breast cancer screening data, published in the April issue of JAMA.
How to best go about achieving that individualization is not entirely clear, but clinicians need to make an effort with the tools that are currently available, such as decision aids and risk models, suggest Lydia Pace, MD, MPH, and Nancy Keating, MD, MPH, both from Brigham and Women's Hospital in Boston, in their review.
The pair evaluated nearly 450 scientific articles from 1960 to 2014 for "evidence on the mortality benefit and chief harms of mammography screening."
After pouring over clinical trials, systematic reviews, meta-analyses, and observational studies, they conclude that the mortality benefit of mammography is "modest" and the risks of harm from screening are "significant."
This mix means that clinicians "must focus on promoting informed screening decisions," they write.
"There is a challenge for physicians to find the time to talk about this with patients," acknowledged Dr. Keating in an email to Medscape Medical News. "I do hope that the increasing availability of decision aids will make these discussions easier."
In an accompanying editorial, another pair of experts echo the main messages of the review.
"Balanced messaging is essential to help each woman make her own individual decision regarding her participation in screening mammography," write Joann Elmore, MD, MPH, from the University of Washington in Seattle, and Barnett Kramer, MD, MPH, from the National Cancer Institute in Bethesda, Maryland.
Discussions about screening "should begin with information about the woman's realistic risk of a breast cancer diagnosis," they add.
However, like Drs. Pace and Keating, the editorialists suggest there is a bit of a glitch in doing this. "The current ability to estimate individual risk is imprecise," they note.
The benefit of mammography is "less than once hoped" and the potential harms are "greater than anticipated," the editorialists write. "Yet that nuanced balance is not easily communicated."
In short, clinicians face a tremendous task when trying to communicate the risks and benefits of mammography screening to individual patients, they suggest.
They do offer some advice for clinicians who sit and talk with women considering screening: "Messages based on fear or guilt may impede full understanding."
Fifty Years of Data
In their review of 50 years of data, Drs. Pace and Keating conclude that mammography screening is associated with a 19% overall reduction of breast cancer mortality (approximately 15% for women in their 40s and 32% for women in their 60s).
But, for a 40- or 50-year-old woman undergoing 10 years of annual mammograms, the cumulative risk of a false-positive result is about 61%.
Additionally, about 19% of the cancers diagnosed during that 10-year period of mammograms would not have become clinically apparent without screening (and thus represent overdiagnosis). However, Drs. Pace and Keating note that "there is uncertainty about this [overdiagnosis] estimate."
Strong Response From Imaging Societies
The analysis from Drs. Pace and Keating met with fierce opposition from 2 medical societies: the American College of Radiology (ACR) and the Society of Breast Imaging (SBI).
In a joint press release, the 2 groups raise the specter of missed cancers and subsequent deaths.
"Breast cancer screening based primarily on risk — as discussed in the JAMA article — would miss the overwhelming majority of breast cancers present in women and result in thousands of unnecessary deaths each year," the statement reads.
Part of the problem with the study is that it relied too much on old data, the groups assert.
"The JAMA article authors also placed too much emphasis on the obsolete and low lifesaving benefit of mammography claimed in outdated or discredited studies," they state.
As an example, the critics cite the Canadian National Breast Screening Study (CNBSS), which is included in the JAMA analysis. CNBSS has been "widely discredited," and the World Health Organization officially excluded it from their analyses of screening's mortality benefit, according to the ACR/SBI statement.

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