Dr. Janet Baum
Demystifies the mammography controversy
By Susie Davidson
Advocate Correspondent
BOSTON - Of all issues facing women today, few carry the universal significance of breast cancer. Compounding the mystery and apprehension of the disease itself are its underlying controversies; specifically, the value of current modalities of detection and the ambiguities of environmental factors or preventative measures. Clarity and/or reassurance can seem elusive at best.
Last week, a Swedish study determined that women who underwent mammography,
especially those over age 55, had a 21 percent lower incidence of death from breast cancer than those who avoided the what for some is a painful, somewhat invasive, screening technique.
But this finding far from settles the long-debate surrounding the procedure. Controversy over mammography has been an issue since two federal panels in 1997 reached contradictory conclusions. Then, a Danish study in January 2000, which was later confirmed by another, further revealed that of eight studies, six had statistical flaws and two showed no benefit.
"There are conflicting studies," acknowledges Dr. Janet Baum, director of breast imaging at Beth Israel Deaconess Medical Center."But one of the problems was that there was wide variation in the subjects - the Canadian data has shown that some patients were already symptomatic for breast cancer, and in many cases, patients who agree to be in these trials are at higher risk due to family history or other factors. Thus, the study would already be biased. Also, some studies followed patients yearly, some every two years, some18 months, and some were one-view mammograms where others were two-view exams.
"Most importantly," she says, "these studies were all based on patients who had mammograms between about 10 and 25 years ago, and there has been a quantum leap in the quality of mammography since the early to mid 90's. What we see and detect today is very different from what we saw then. We are now picking up smaller lesions, and are more aware of multiple sites of disease in the same breast. Follow-up treatment has clearly improved as well, which also presents a problem in analyzing survival rates."
So mammography is still viable as well as valuable?
"I think it is still the gold standard; it's still the best thing we have," Dr. Baum responds, but cautions: "People think it detects all cancers, which is a mistake. The best mammogram, even today, still misses somewhere between ten and 15 percent of all cancers."
Given this reality, Dr. Baum advises supplementary clinical exams, and says that self-exams don't hurt either.
"Dr.Susan Love is against breast self exam," she says, "but what is most important is that a woman knows what the normal lumps and bumps in her breasts are."
What about the slight increase in breast cancer rates among Jewish, specifically Ashkenazic, women? "We know that at least some of it is related to genetics," she replies. "Part of it may be the genes we know about, BRCA 1 and 2, and unknown genes as well. We know that more highly educated groups have a higher incidence. Fewer and later pregnancies, later ages of primary menstruation, professional women - these additional factors can also be common among Jewish women."
Also, she explains, some women die of unrelated, other causes, and sometimes tiny "foci" of breast cancer, discovered in autopsy, would not have grown enough to affect mortality. "Some cancers might never amount to much," she says.
She analogizes prostate cancer in men. "It's now said that if every man lives long enough, they will get it, yet most of it - possibly a tiny focus, a couple of cells, will not be significant for the life of that individual. Yet, we don't hear all these questions about why men don't get PSA tests," she points out.
The modern environment is consequential as well, she says. "Today, we have better health care, better diet, longer years of hormonal stimulation - and hormones in the foods we eat (she cites chicken breasts as containing estrogens)."
But there now exist options for better and less disfiguring treatment as well. "60 to 75 percent of all women in the U.S. now have lumpectomies," she estimates, "and 75 percent in the New England area alone." There have been 20 to 30 years of follow-up studies now on lumpectomies, she adds.
"There are new therapies, new hormonal regimens such as tamoxifen. They are clearly helping to increase survival rates, which also make it difficult to evaluate mammography alone."
Newer modes of treatment are coming, she says, and detection will also continue to improve, including "double reading" or computer-aided detection, MR and ultrasound and selected screening of higher-risk individuals. "We are looking at other ways to increase the sensititivy of mammography," she says, and cites an ongoing national study comparing the efficacy of digital mammography over traditional film-screen mammography. BI/Deaconess is one of 18 sites for this effort, and will enroll 2500 out of the study's 50,000.
For women interested in participating in this trial, the web site (www.dmist.org) provides information; they can also call 617-667-2514.