40代の約2/3は過去2年以内にマンモグラムを受け、50〜65才では72%が受けている。1年おきの検査で害を半分に減らせ、利益はほとんど変わらないとテキサス大のDr. Berry は言う。
Screening for Breast Cancer: U.S. Preventive Services Task Force Recommendation Statement
Effects of Mammography Screening Under Different Screening Schedules: Model Estimates of Potential Benefits and Harms
Panel Urges Mammograms at 50, Not 40
By GINA KOLATA
Published: November 16, 2009
Most women should start regular breast cancer screening at age 50, not 40, according to new guidelines released Monday by an influential group that provides guidance to doctors, insurance companies and policy makers.
The new recommendations, which do not apply to a small group of women with unusual risk factors for breast cancer, reverse longstanding guidelines and are aimed at reducing harm from overtreatment, the group says. It also says women age 50 to 74 should have mammograms less frequently ― every two years, rather than every year. And it said doctors should stop teaching women to examine their breasts on a regular basis.
Just seven years ago, the same group, the United States Preventive Services Task Force, with different members, recommended that women have mammograms every one to two years starting at age 40. It found too little evidence to take a stand on breast self-examinations.
The task force is an independent panel of experts in prevention and primary care appointed by the federal Department of Health and Human Services.
Its new guidelines, which are different from those of some professional and advocacy organizations, are published online in The Annals of Internal Medicine They are likely to touch off yet another round of controversy over the benefits of screening for breast cancer.
Dr. Diana Petitti, vice chairwoman of the task force and a professor of biomedical informatics at Arizona State University, said the guidelines were based on new data and analyses and were aimed at reducing the potential harm from overscreening.
While many women do not think a screening test can be harmful, medical experts say the risks are real. A test can trigger unnecessary further tests, like biopsies, that can create extreme anxiety. And mammograms can find cancers that grow so slowly that they never would be noticed in a woman’s lifetime, resulting in unnecessary treatment.
Over all, the report says, the modest benefit of mammograms ― reducing the breast cancer death rate by 15 percent ― must be weighed against the harms. And those harms loom larger for women in their 40s, who are 60 percent more likely to experience them than women 50 and older but are less likely to have breast cancer, skewing the risk-benefit equation. The task force concluded that one cancer death is prevented for every 1,904 women age 40 to 49 who are screened for 10 years, compared with one death for every 1,339 women age 50 to 59, and one death for every 377 women age 60 to 69.
The guidelines are not meant for women at increased risk for breast cancer because they have a gene mutation that makes the cancer more likely or because they had extensive chest radiation. The task force said there was not enough information to know whether those women would be helped by more frequent mammograms or by having the test in their 40s. Other experts said women with close relatives with breast cancer were also at high risk.
Dr. Petitti said she knew the new guidelines would be a shock for many women, but, she said, “we have to say what we see based on the science and the data.”
The National Cancer Institute said Monday that it was re-evaluating its guidelines in light of the task force’s report.
But the American Cancer Society and the American College of Radiology both said they were staying with their guidelines advising annual mammograms starting at age 40.
The cancer society, in a statement by Dr. Otis W. Brawley, its chief medical officer, agreed that mammography had risks as well as benefits but, he said, the society’s experts had looked at “virtually all” the task force and additional data and concluded that the benefits of annual mammograms starting at age 40 outweighed the risks.
Other advocacy groups, like the National Breast Cancer Coalition, Breast Cancer Action, and the National Women’s Health Network, welcomed the new guidelines.
“This is our opportunity to look beyond emotions,” said Fran Visco, president of the National Breast Cancer Coalition. The task force “is an independent body of experts that took an objective look at the data,” Ms. Visco said. “These are the people we should be listening to when it comes to public health messages.”
Some women, though, were not pleased. “I know so many people who had breast cancer and survived, and what saved their lives was early detection,” Janet Doughty, 44, of San Clemente, Calif., said in a telephone interview. She said she had had an annual mammogram since her late 30s and would not stop now.
The guidelines are not expected to have an immediate effect on insurance coverage but should make health plans less likely to aggressively prompt women in their 40s to have mammograms and older women to have the test annually.
Congress requires Medicare to pay for annual mammograms. Medicare can change its rules to pay for less frequent tests if federal officials direct it to.
Private insurers are required by law in every state except Utah to pay for mammograms for women in their 40s.
But the new guidelines are expected to alter the grading system for health plans, which are used as a marketing tool. Grades are issued by the National Committee for Quality Assurance, a private nonprofit organization, and one measure is the percentage of patients getting mammograms every one to two years starting at age 40.
That will change, said Margaret E. O’Kane, the group’s president, who said it would start grading plans on the number of women over 50 getting mammograms every two years.
The message for most women, said Dr. Karla Kerlikowske, a professor in the department of medicine, epidemiology and biostatistics at the University of California, San Francisco, is to forgo routine mammograms if they are in their 40s.
Starting at age 50, Dr. Kerlikowske said, “the message is to get 10 mammograms in a lifetime, one every two years.” That way they get the most benefit and the least harm from the test. If women are healthy, she added, they might consider having mammograms every two years until age 74.
Nearly two-thirds of all women in their 40s had mammograms within the last two years, as did 72 percent of women age 50 to 65, according to an editorial by Dr. Kerlikowske that accompanies the report.
In order to formulate its guidelines, the task force used new data from mammography studies in England and Sweden and also commissioned six groups to make statistical models to analyze the aggregate data. The models were the only way to answer questions like how much extra benefit do women get if they are screened every year, said Donald A. Berry, a statistician at the University of Texas M. D. Anderson Cancer Center and head of one of the modeling groups.
“We said, essentially with one voice, very little,” Dr. Berry said. “So little as to make the harms of additional screening come screaming to the top.”
The harms are nearly cut in half when women have mammograms every other year instead of every year. But the benefits are almost unchanged.
The last time the task force issued guidelines for mammograms, in 2002, the reportwas announced by Tommy G. Thompson, the secretary of health and human services. When the group recommended mammograms for women in their 40s, some charged the report was politically motivated. But Dr. Alfred Berg of the University of Washington, who was the task force chairman at the time, said “there was absolutely zero political influence on what the task force did.”
It was still a tough call to make, Dr. Berg said, adding that “we pointed out that the benefit will be quite small.” In fact, he added, even though mammograms are of greater benefit to older women, they still prevent only a small fraction of breast cancer deaths.
Different women will weigh the harms and benefits differently, Dr. Berg noted, but added that even for women 50 and older, “it would be perfectly rational for a woman to decide she didn’t want to do it.”
Researchers worry the new report will be interpreted as a political effort by the Obama administration to save money on health care costs.
Of course, Dr. Berry noted, if the new guidelines are followed, billions of dollars will be saved.
“But the money was buying something of net negative value,” he said. “This decision is a no-brainer. The economy benefits, but women are the major beneficiaries.”
Roni Caryn Rabin contributed reporting.
This article has been revised to reflect the following correction:
Correction: November 19, 2009
An article on Tuesday about revised guidelines on breast cancer screening misstated a statistic from the United States Preventive Services Task Force, which released the recommendations. The task force concluded that one cancer death was prevented for every 1,339 women aged 50 to 59 who were screened for 10 years ― not 50 to 74.
Yearly Mammograms Undergo Scrutiny
Dr. Marie Savard Explains Why Some Cancer Screenings May Do More Harm Than Good
By MARIE SAVARD, M.D.
ABC News Medical Contributor
Nov. 17, 2009
Screening tests for early detection of cancer have undergone a lot of scrutiny lately. Just a few weeks ago the American Cancer Society (ACS) issued a press release reminding us that the Cancer Society may have overstated the benefits of screening and underemphasized the potential harm when it came to testing for early breast and prostate cancer.
The ACS went on to discuss the limitations of screening women for early breast cancer with mammograms and screening men for prostate cancer with the simple PSA blood test.
This week, the United States Preventive Task Force (USPTF) issued new guidelines for breast cancer screening. I suspect that explains why the ACS issued its recent comments, knowing these guidelines were about to be released.
The USPTF analyzed various mammography screening schedules and concluded that:
1) Women under the age of 50 should not be screened with routine mammograms because proven benefits are lacking and the risks of harm (such as unnecessary biopsies from false positive results, especially in women with dense breasts) are greater.
2) Screening women of average risk between the ages of 50 and 74 with mammography every two years will achieve most of the benefits of yearly screening, but with less harm.
3) The task force also recommends against teaching breast self-exam.
So why the new recommendations? What new information do we have on the behavior of breast cancers and mammograms?
Many scientists believe that there are two types of cancers.
First there are those that appear suddenly, grow rapidly, act aggressively, and often are diagnosed when it is already "too late" for curative treatment. Even a yearly mammogram might not diagnose this aggressive breast cancer in the early stages.
But for many women (and men when it comes to the prostate) their cancers are of a second type -- they are very slow growing, often not even showing up on mammograms for many years. These slow cancers are thought to be much less aggressive. Some experts are even suggesting that these cancers may either disappear on their own or would not cause injury or death to the person with them, even without treatment.
Can Cancers Disappear on Their Own?
A recent study in the Journal of the American Medical Association (JAMA) pointed out the evidence for this. Breast cancer statistics for women in the Unites States has not shown a reduction of advanced breast cancers being diagnosed, despite the widespread use of mammography.
One would expect that if mammograms diagnosed breast cancers earlier and women were then treated for these cancers, over time there would be a reduction in the diagnosis of more advanced cancers from the "successful" screening. But this is not the case. Advanced cancers continue to be diagnosed with greater than expected frequency.
For men, the same seems to be true for prostate cancers. Many men will develop prostate cancer if they live long enough, yet many of these cancers will not cause problems and don't need to be treated. However the simple PSA blood test, like the mammogram for women, does not distinguish the slow growing from the more aggressive fast growing ones.
On the other hand, for both men and women who are equally at risk for colon cancer, screening and early diagnosis and treatment has led to a significant reduction in the number of more advanced cases of colon cancer diagnosed. So when it comes to colon cancer, early detection and removal of any precancerous polyps or early cancers really make a difference.
The same is true for Pap tests in women. Pap tests are also a great screening success story (read my recent blog on the value of adding the HPV test to your Pap test if you are 30 or older). Women who have an abnormal Pap test will have their abnormal cells diagnosed and treated early and are therefore much less likely to be diagnosed with advanced cervical cancer.
Australian researchers have found that as many as a third of women diagnosed with breast cancer may not need treatment. The researchers from the University of Sydney say they found that screening with mammograms is far from perfect and women often go on to have surgery and chemotherapy that is unnecessary because the cancers detected are slow-growing and not life-threatening. Unfortunately, our current screening with mammography -- even the more detailed digital mammography -- can't distinguish between slow-growing and aggressive ones.
Benefits and Risks of Mammograms
I talked about some of the other potential risks of mammograms including radiation exposure in a column last February titled "Deja Vue: Questions about the Timing Of Mammograms."
What about women with a strong family history of breast cancer or those who have inherited the BRCA 1 or BRCA 2 gene? The USPTF was clear to address only women at average risk for breast cancer and not those women at particularly high risk.
For high-risk women, an MRI scan of the breast for breast cancer screening is thought to be more sensitive than mammograms and therefore more likely to pick up subtle breast changes or early breast cancer and it is not associated with ionizing radiation.
But we still do not have enough research on screening MRIs in young high-risk women to know if they are safe, effective, and worth the greatly added cost (both in dollars and in needless biopsies, scares, missed work, etc.).
I suggest that until we learn more about the benefits and risks of MRIs, every woman at high risk should talk with her doctor about the pros and cons of all available tests, including routine mammogram, breast ultrasound and periodic breast MRI.
Every woman's medical history and breast exam will be different and only when all aspects of a woman's history are taken into account can the best decision for screening be made. In the end, the decision should be made between a woman and her doctor.
In addition to a detailed conversation with your practitioner about the best way to be protected, all women should:
1) Be familiar with how your breasts feel and what is normal for you -- and do not hesitate to examine your breasts and to report any change or concerns to your practitioner
2) Continue to expect a regular breast examination by your practitioner, regardless of your risk factors.
3) Discuss the benefits and risks of routine mammograms with your practitioner if you are between the ages of 40 and 50.
4) Continue having a yearly mammogram starting at age 50.
5) Ask about getting a more sensitive digital mammogram or breast ultrasound if your breasts are very lumpy or dense
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