Blake Cady, MD, professor of surgery (emeritus), Harvard Medical School, Boston. His study was published in Cancer.
“I might be dead by now if I had done what those guidelines are now telling women to do. In fact, I think it’s just plain crazy to say that we shouldn’t start getting mammograms until we’re 50 or that we shouldn’t get them every year!” a friend of one of our colleagues said. That was several years ago, right after the US Preventive Services Task Force issued its controversial recommendations to limit breast cancer screening.
Her outrage was understandable. Ten years ago, when she was 45, a routine screening mammogram revealed a tumor in her breast—a tumor that had not been evident at her previous mammogram 12 months before. Her cancer would not have been diagnosed nearly so early if the current Task Force guidelines had been in effect at the time. She was treated successfully, thank goodness, and is cancer-free today—so even though the Task Force characterizes the benefits of screening for women like our colleague’s friend as small, she herself calls the benefit immeasurably huge.
Now a new study from Harvard has reignited the controversy surrounding who should and should not have routine mammograms…how often those tests should be done…and the ages at which screening should start and stop. Since this new research contradicts the Task Force recommendations, women are left wondering, Whom should we listen to? So Daily Health News went after the answer…
Two aspects of the Task Force recommendations sparked outrage among many women (and many doctors, too)—the idea that women in their 40s did not need routine mammograms…and that screening should take place every other year rather than yearly. When challenged, the Task Force defended its position, asserting that “although the benefit of screening seems equivalent for women aged 40 to 49 years and 50 to 59 years, the incidence of breast cancer and the consequences differ.” It further claimed that the test’s “harms”—such as inconvenience, discomfort and the risk for false-positive results—outweighed its benefits for women under age 50 and warranted the less-frequent screening schedule for older women.
However, the Harvard researchers now contend that the previous studies on which the Task Force recommendations were based had gone about their calculations all wrong—and that lives would be saved if women were screened more frequently and at a younger age.
The new study is of a type called a failure analysis. Such analyses look backward from death to discover correlations at diagnosis, rather than looking forward from the beginning of a randomized trial—a technique that eliminates problems of noncompliance and “contamination biases” that can skew results.
Researchers from two major academic teaching hospitals in Boston reviewed their records for women who were diagnosed with potentially curable (stage I, II or III) invasive breast cancer between 1990 and 1999 and followed through 2007. They found 7,301 such patients…and of those, 609 died from breast cancer during the follow-up period.
The researchers analyzed these 609 confirmed breast cancer deaths, comparing screened women (those who had had a mammogram at least every two years in the absence of symptoms) with unscreened women (those who never had a mammogram or hadn’t had one within two years of their cancer diagnoses). What they found…
The vast majority of deaths, or 71%, were among unscreened women—even though unscreened women accounted for only 20% of the total patient population in the study. Of the women who died, 65% had never had a screening mammogram…and 6% had not had a mammogram for at least two years prior to their diagnoses. Only 29% of the deaths were among screened women. The fact that most of the women who died were not participating in screening clearly supports the importance of early detection through mammography, the researchers said.
Of all breast cancer deaths, a startlingly high 50% were in women younger than 50—the very same age group that, under the current Task Force guidelines, would not be expected to benefit from screening mammograms!
Among patients younger than age 50, the breast cancer death rate was 13%—nearly double the 7.6% death rate for the patients between ages 50 and 74. Likely reason: The Harvard researchers pointed out that the biological nature of breast cancer in young women is more aggressive than in older women.
Interval cancers are those that are detected when they cause actual symptoms in the interval between a normal, negative mammogram and a woman’s next regularly scheduled mammogram. Among screened women who were diagnosed in their 40s, 47% of those who died had interval cancers…whereas among screened women who were diagnosed in their 60s, only 24% of those who died had interval cancers. These findings, the researchers said, suggest that it’s appropriate to do more frequent screening in women younger than 50 and less frequent screening in women age 60 and up.
Bottom line on breast cancer screening: By definition, screening refers only to people who have no signs or symptoms of a disease. If you do have possible symptoms of breast cancer (a lump, thickening of tissue, nipple discharge, inverted nipple, dimpling or other skin changes), it is vital that you get a diagnostic mammogram to start the process that can determine whether or not your symptoms are caused by cancer.
It’s also important to note that screening recommendations apply to the public in general. Women at increased risk for breast cancer often are advised to begin screening earlier, to screen more often and/or to screen with other technologies (such as ultrasound or MRI) in addition to mammography. So if you have a family history of breast cancer, had a previous biopsy with high-risk though benign results or have tested positive for the BRCA1 or BRCA2 gene, ask your doctor to provide details on the most appropriate screening schedule and methods for you.
Absent such risk factors, however, the researchers from this new study suggested that, in general, “a screening sequence that corresponds to the biological behavior of breast cancer” would be for women to get mammograms every six to 12 months in their 40s…every year in their 50s…every two years in their 60s…and every two to three years from age 70 onward until life expectancy is less than 10 years.
The researchers put it this way: Participating in mammography is like buying home owners’ insurance. You pay a premium even though you’re unlikely to ever need to file a claim—but in the event of disaster, you are protected from ruin. With breast cancer, the disaster of death is largely avoided due to early detection.
For much more on breast cancer: Read Bottom Line’s Breast Cancer Guide: Prevent, Detect, Treat, Recover.