Mammograms Experts Divided Over Whether Yearly X-Ray Screening For Women In Their 40s Actually Saves Lives
A national panel of breast cancer experts recently reviewed everything science has learned about whether women in their 40s should have mammograms.
The panel concluded that, despite years of study and debate, science still does not know for sure whether mammograms save or prolong the lives of women under 50.
The panel left women to make sense of the mammogram muddle.
For women like Zora Brown Kramer, 48, there is no doubt what to do. As an African-American woman who has had breast cancer and whose family has fought the disease for three generations, she considers mammography essential.
“I had my first mammogram at age 21 and was diagnosed with breast cancer 10 years later,” Brown, founder of a breast-cancer advocacy group in Washington, D.C., told the panel. “I have become dismayed and disturbed by the controversy in the scientific community.”
But for millions of middle-age baby boomers - women already scratching their heads over possible breast cancer risks from hormone therapy for menopause - the panel’s statement left them feeling confused and defenseless in the face of a physically, emotionally and sexually devastating disease.
What’s a fortysomething woman to do?
Women’s dilemma difficult
The dilemma faced by the panel - and by every woman - is tough to resolve.
Because cancer is uncommon among women in their 40s, and because their relatively dense breast tissue is hard to read on a breast X-ray, they have a far greater chance of an inaccurate mammogram than of being diagnosed with cancer. And an inaccurate mammogram carries its own risks: the risk of unnecessary further testing or the risk that cancer was missed.
There are other downsides.
There’s a theoretical risk from cumulative mammographic radiation (perhaps one death per 10,000 women over a 10-year period). And there’s a good chance that if a tumor is detected, it will be the pre-invasive kind, which probably will be treated even though it may never turn cancerous.
The panel had the unenviable task of balancing these negative factors against the latest research on “mortality benefits,” that is, data showing whether mammograms save lives.
Increasingly, the research picture suggests a mortality benefit for women in their 40s, but not a strong or clear-cut benefit. And this benefit has emerged not because of brand-new studies but because the eight studies conducted in four countries during the past 34 years have continued to follow the women who received mammograms years ago.
These eight studies are tricky to compare. The number of mammograms per woman and the intervals between mammograms varied. So did the numbers of women enrolled.
And mammogram equipment in the earliest study was the equivalent of a Model T.
Still, all the studies used the same approach: Divide women into two groups - those who received mammograms and those who didn’t - then follow them to see which group had fewer breast cancer deaths.
For women over 50, the results were unequivocal and showed up within five years. Mammograms reduced deaths by a third.
For younger women, the mortality benefit was unclear.
At a 1993 National Cancer Institute workshop, a meta-analysis (a superstudy that included results from all eight studies) found no benefit at seven years of follow-up: Women lived just as long, whether they’d been screened or not.
However, there were nuances.
The oldest study, considered alone, found a 25 percent benefit after 10 to 18 years of follow-up. Four Swedish studies showed a 10 percent to 13 percent benefit after 12 years of follow-up, although this was not statistically significant.
Then came the breakthrough.
New analysis shows benefit
Last April, an updated meta-analysis of the studies showed, for the first time, a statistically significant mortality benefit of 24 percent, 23 percent or 15 percent, depending on which studies were included.
These important new findings prompted the National Institutes of Health to assemble the panel that last week reconsidered the question of screening women in their 40s.
The panel heard up-to-the-minute analyses by scientists from around the world.
The bottom line: Screening women in their 40s might reduce their breast cancer mortality by about 16 percent.
Put another way, if you screen 10,000 women in their 40s annually for 10 years, four lives might be saved - one out of 2,500.
But this heartening picture was fuzzy. Researchers could not be sure whether the emerging mortality benefit was due to the original mammograms, or to something else, such as the women developing cancer in their 50s, when mammograms are recommended anyway.
In the face of fuzziness, researchers are divided.
Daniel B. Kopans, a radiologist at Harvard Medical School, told the panel, “There has been evidence for years and now there’s statistically significant proof” that mammograms benefit younger women.
Anthony B. Miller, director of the Canadian National Breast Cancer Screening Study, the only study specifically designed to look at screening younger women, said, “It has failed to demonstrate a delayed benefit or a benefit at any stage.”
Radiologist Ingvar Andersson, head of a Swedish study, said, “In my mind, there is no doubt you can decrease mortality through screening women below age 50. But I also think the balance between the negative and positive effects is unclear.”
For a woman trying to sort it all out, the decision may boil down to how much she fears breast cancer, said Karla Kerlikowske, an epidemiologist and associate director of a woman’s clinic in San Francisco.
“If you’re risk-averse, then you tend to want to screen more,” Kerlikowske said. “And if you’re not, you don’t. So it depends on the kind of person you are.”
xxxx HERE ARE POINTS TO TAKE INTO ACCOUNT Here are some things to consider in deciding whether to have yearly mammograms:
Your chances of cancer. A 40-year-old woman has a 1.5 percent chance of getting cancer in the next 10 years and a 3-in-1,000 chance of dying of it. Suzanne Fletcher of Harvard Medical School looks at it this way: For every 1,000 women aged 40, about 16 will develop cancer by age 50. About half of these 16 women will survive, regardless of whether they were regularly screened, partly because of therapeutic advances.
Mammography is life-saving. The research indicates screening reduces mortality among women in their 40s by about 16 percent, compared with 34 percent for women in their 50s. Again, that means screening 10,000 women in their 40s annually for 10 years would save four lives, compared with saving 37 lives by screening women in their 50s. The benefit for younger women may be overestimated, primarily because some study subjects who had mammograms in their 40s got cancer in their 50s. On the other hand, this benefit may be underestimated because mammographic technology has improved dramatically in recent years.
Earlier cancer is easier to treat. Small tumors may be treated with lumpectomy (breast-conserving surgery) rather than breast removal. Small, early cancers are less likely to have spread to lymph nodes and may need little or no radiation and chemotherapy. However, there is evidence that younger women are more prone to fast-growing, aggressive cancers that may spread microscopically and defy cure, even with early detection. That’s why scientists now say women in their 40s who opt for mammograms should have them annually.
Mammography isn’t perfect. It misses one-fourth of invasive breast cancers in women ages 40 to 49, compared with one-tenth of cancers in women 50 to 59. On the flip side, 11 percent of all mammograms suggest cancer when none is present. A 40-year-old woman who is screened annually for a decade has almost a 1-in-3 chance of having such a “false positive,” compared to a 1-in-4 chance for a 50-year-old. To discover the mistake, she’ll have to undergo extra tests - and more anxiety, discomfort and expense. There’s a 7 percent chance the extra tests will include a biopsy.
Mammography is radiation. No one has ever been shown to have contracted cancer from mammographic X-rays, but theoretically, it’s possible, even with today’s ultralow doses of radiation. The younger a woman is when she starts getting mammograms, the greater her cumulative lifetime risk. Experts estimate mammograms may account for one added breast cancer death per 10,000 women who get annual mammograms in their 40s.
The downside to early detection. Thanks to mammography, more cancers are being caught early, but a growing number of these are pre-invasive cancers, restricted to the milk ducts, that may never become life-threatening. They now account for 15 percent of breast cancers among women in their 40s. The problem is that doctors can’t predict whether they’ll become malignant, so the lesions are usually removed, sometimes by mastectomy. The physical and emotional toll can be great. Marie McCullough Philadelphia Inquirer