Thursday’s announcement by top government health officials that women 40 and older should get mammograms every year or two cleared up all the confusion.
Or maybe not.
The fine print in the new recommendations by the U.S. Preventive Services Task Force said each woman should decide for herself, in consultation with her clinician, when to start getting screened for breast cancer and how often to have the test. It said she needs to weigh the potential harm of mammography against the promised benefit and factor in her own personal risk factors, values and preferences.
That’s a tall order.
Life was much easier when we just did what The Doctor told us to do. And if that’s your inclination, there are still plenty of doctors who will be happy to tell you to get a mammogram every year starting as soon as you turn 40. Period.
But if you’ve been at all troubled by recent studies casting doubt on the lifesaving benefit of screening mammograms, or by the relatively new admission that the commonplace X-ray also has some risks, then you’re probably at sea.
Like other well-educated and well-insured women of my generation, I have had an annual mammogram and a clinical breast exam every year since I turned 40.
Like other women who are smart enough to know better, I believed superstitiously that my vigilance was keeping the breast cancer monster at bay.
Of course, mammograms don’t prevent breast cancer. The recent study by two Danish researchers that created such an uproar a few months ago suggests they may not even prevent deaths from breast cancer.
How could that be? Isn’t it patently obvious that finding a malignant breast tumor earlier has to be better than finding it later? Don’t we have clear proof that women with smaller cancers have a better chance of surviving the disease?
As it turns out, those questions have no clear answers.
Early detection is useful if there is a window of opportunity in which treatment leads to more or better cures. Early detection doesn’t help if the patient could have been treated just as successfully later. Conversely, if the treatment is unsuccessful, it’s possible the only effect of early detection was that the patient spent more of her remaining life battling a fatal malady.
Likewise, smaller breast cancers generally do have a better prognosis. And mammograms tend to find smaller cancers. But that doesn’t necessarily mean mammograms are responsible for improved outcomes.
If mammograms are finding small tumors that would not have gone on to become big and dangerous, then the main effect of screening is to increase the incidence of breast cancer–not to reduce breast cancer deaths.
Unfortunately, there is some evidence of that. Mammograms are largely responsible for overdiagnosis–that is, detecting cancers so slow-growing that they would never become life-threatening before the patient died of something else. And because no one can tell for sure which ones are lethal and which aren’t, nearly all breast cancers get the standard slash, poison and burn treatment.
Women need to perform a fairly complicated calculus to figure out whether having a mammogram makes sense. First you need to understand the test’s benefit–a concept on which even experts in statistics and epidemiology can’t agree. How many lives does it save? How confident can we be in the evidence?
Then you need to weigh that benefit against the hazards of the tests, including the unquantifiable risk of being diagnosed with and treated for something that would never have hurt you.
In the two years I have spent researching this topic, I have come face-to-face with one unwelcome truth after another:
– Mammography is a pretty imprecise test. It misses about one-fifth of the cancers. It flags a huge number of suspicious findings that are not cancerous. And competent radiologists can look at the same images and draw different conclusions.
– Some breast cancers are so virulent they will probably kill you even if you catch them “early,” on a mammogram.
– Others are so slow-growing they will never become life-threatening.
– Routine screening mammograms are more likely to find the innocuous ones than the aggressive ones.
Throughout this project, friends and colleagues have asked me repeatedly: “So? Knowing all of this, are you still going to have regular mammograms?”
My answer is a somewhat equivocal “yes”–though probably not every year. (There’s no scientific evidence that annual screening is any more effective than screening every other year, at least for women over 50.)
Had I known at 40 what I know now, I might have skipped the first decade of mammograms. But now that I’m past 50, I’m willing to risk the downside of screening for a possible reduction–albeit very small–in the probability that I will die of breast cancer. (Because, until we have much more definitive evidence that mammograms don’t save lives, I believe it’s reasonable to assume there is a small mortality benefit.)
We have been inundated with the message that 1 in 8 of us will get breast cancer if we live long enough; we need to feel there’s something we can do about it.
But some women are less afraid of the cancer bogeyman, or have a different approach to risk in general, and they might well conclude the harm of the test outweighs the benefit.
(Remember I’m talking about screening mammograms, which by definition are done on healthy women. There’s no question you need to have a diagnostic mammogram if you have any symptoms that might indicate breast cancer.)
I could rationalize my own decision to continue being screened by saying my risk of getting breast cancer is higher than the average woman’s because my mother died of it. But 75 percent of breast cancer patients have no special risk: The biggest risk factors for breast cancer are being female and getting older, so every woman is at risk.
The real reason is that, despite the inadequacies of mammography, we don’t have anything better. As my internist, Dr. Emily Gottlieb, put it: “We know it’s not an exact science, but we don’t abandon it. It’s the best we’ve got right now.”
I believe that, before my daughters have adult daughters of their own, breast cancer screening will become unnecessary because improved treatment will make the disease curable–or at least manageable–no matter when it’s detected.
I think it’s also very likely that within the next decade we will have molecular diagnostic tools that will make it possible to predict with a high degree of certainty which malignancies need to be treated (and with what specific therapies) so doctors won’t have to bring out the heavy artillery to combat tumors that could just be watched.
In the meantime, I will go on having mammograms and clinical breast exams. But I promise not to panic the next time a doctor finds something suspicious.
