HANOVER, N.H. — A COUPLE of months ago, JAMA Internal Medicine, a journal of the American Medical Association, published the findings of a brief online survey of middle-aged Americans.Most had previously been screened for either breast or prostate cancer. But the study found that about half said they would not choose to start screening if the test resulted in more than one overtreated person per one cancer death averted.
Connect With Us on Twitter
For Op-Ed, follow @nytopinion and to hear from the editorial page editor, Andrew Rosenthal, follow @andyrNYT.
Wow. That implies that millions of Americans might choose not to be screened if they knew the whole story — that overtreatment is typically more common than avoiding a cancer death.
Is the survey right? Honestly, I have no idea. Different surveys get different answers. According to surveys, most of us hate Obamacare. But a number of us like the Affordable Care Act (another name for the same thing). And most of us like the bulk of the individual components of the law. How you ask the question matters.
Similarly, how Americans feel about screening is obviously related to what they are told about screening. Most of the time they get a simple message: It's the most important thing they can do to stay healthy. Occasionally, they may hear just the opposite: It's dangerous. The truth is, it's neither.
Instead, it's a close call. Different people in the same situation can rationally make different choices. But first, patients need some quantification of the benefits and harms.
In a study to be published Monday, Dec. 30 in JAMA Internal Medicine, a colleague and I attempt to provide that data for women making the choice about screening mammography. Let's be clear at the outset: There is a lot of uncertainty — and professional disagreement — about what the data are. So we provide a range of estimates, from optimistic to pessimistic.
There is no doubt that screening mammography in the United States leads to a lot of false alarms. Among a thousand 50-year-old American women screened annually for a decade, how many will have at least one false alarm? Our estimate ranges from 490 to 670. The data come from the mammographers themselves — the Breast Cancer Surveillance Consortium — and reflect radiologists who deliver low and high rates of false alarms (those in the 25th and 75th percentiles).
A screening program that falsely alarms about half the population is outrageous. To be sure, many women are quickly reassured by a second test that their breast is normal. But others — while told they don't have cancer — are told that their breast is somehow abnormal, that they have dysplasia or atypia, that they are at "high risk." Whether you blame the doctors or the system or the malpractice lawyers, it's a problem that needs to be fixed.
Then there is the problem of overdiagnosis: the detection of a "cancer" that was not destined to ever cause problems. Overdiagnosis is what leads to overtreatment. A decade ago doctors debated whether this problem existed in breast cancer. Now the debate is about how often it occurs.
In a pamphlet to help women decide about mammography screening in Britain, the National Health Service now explicitly tells women that their chance of overdiagnosis is about three times higher than their chance of avoiding a breast-cancer death. I can't tell you if that is the right estimate; since most everyone who receives a diagnosis of "cancer" is treated, overdiagnosis is rarely observed directly, so it is notoriously difficult to quantify. But I can tell you it's in the ballpark. Our optimistic/pessimistic finding is this: Among a thousand 50-year-old American women screened annually for a decade, 3 to 14 will be overdiagnosed and overtreated.
What about the benefit? Among those thousand women, 3.2 to 0.3 will avoid a breast-cancer death. If you don't like decimals, call it 3 to 0.
The optimistic estimate reflects the most favorable result of the nine most comprehensive randomized trials of breast cancer screening. But these trials were initiated 20 to 50 years ago. Whether their results are still relevant is a question. Because of substantial improvements in breast cancer treatment, many cancers that would have been deadly 20 years ago now no longer are. The better we are able to treat cancer, the less important it is find it early; in other words, there are fewer deaths for screening to help avoid. This is what is reflected in the pessimistic estimate. One study comparing regions with similar populations and health care systems, but different screening policies (like Sweden versus Norway and Northern Ireland versus the Republic of Ireland), found that breast cancer death rates had declined at similar rates, regardless of when mass screening was adopted.
So put it all together. Among a thousand 50-year-old American women screened annually for a decade, 3.2 to 0.3 will avoid a breast cancer death, 490 to 670 will have at least one false alarm and 3 to 14 will be overdiagnosed and treated needlessly. That may help some women choose whether to be screened or not. But it's still not very precise, and it doesn't answer the fundamental question: Now that treatment is so much better, how much benefit does screening actually provide? What we need is a clinical trial in the current treatment era.
Two randomized trials could begin to answer the central question of mammography interpretation: How hard should the radiologist look? Women who view mammography favorably might be willing to be screened under either the current approach or a high-threshold approach — meaning their radiologist would ignore small, likely harmless abnormalities found on a mammogram.Those who view it less favorably might choose that high-threshold approach (knowing that the harms of false alarms and overdiagnosis would be minimized) or forgo mammography completely.
Putting the two trials together, we could finally learn what level of screening minimizes false alarms and overdiagnosis while saving the most lives. Most experts would say that it's never going to happen. It would cost too much, take too long and need too many subjects.
Maybe they are right. But maybe not. Sure, it would cost millions of dollars. But that's chicken feed compared with the billions of dollars we spend on breast cancer screening every year. Sure, it would take 10 to 15 years. But it would help our daughters know more. Sure, it would take tens of thousands of women to participate. But maybe they would want to be part of the effort to help sort out the morass surrounding what is one of the most common medical interventions done to American women.
You never know, until you ask.
None of this should dissuade women from seeking a diagnosis when they develop a new breast lump (that's a form of early diagnosis we all agree on) or from seeking treatment for a diagnosed breast cancer (better treatment, not early detection, is the real success story in breast cancer). The uncertainties are about screening. Women who want to reduce those uncertainties will have to participate in trials.
H. Gilbert Welch is a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice and an author of "Overdiagnosed: Making People Sick in the Pursuit of Health."
Anda sedang membaca artikel tentang
Op-Ed Contributor: Breast Cancer Screenings: What We Still Don’t Know
Dengan url
http://opinimasyarakota.blogspot.com/2013/12/op-ed-contributor-breast-cancer.html
Anda boleh menyebar luaskannya atau mengcopy paste-nya
Op-Ed Contributor: Breast Cancer Screenings: What We Still Don’t Know
namun jangan lupa untuk meletakkan link
Op-Ed Contributor: Breast Cancer Screenings: What We Still Don’t Know
sebagai sumbernya
0 komentar:
Posting Komentar