Photo by Todd McNaught
By BARBARA BERG
Results of a long-running Public Health Sciences Division study raise doubts about the value of a common breast-cancer screening technique, the breast self-exam.
A 12-year trial involving more than 266,000 female factory workers in the mainland Chinese city of Shanghai found that women who received intensive instruction in breast self-exam suffered no fewer deaths from breast cancer than women who did not.
The results were announced Tuesday.
Dr. David Thomas, who led the trial, said that more studies are needed to assess whether breast self-exam reduces breast-cancer mortality in women who perform the technique frequently and competently or in those who receive regular mammograms.
Yet the results make clear that allocating money for large-scale breast self-exam training programs in the absence of mammographic screening has no effect on saving lives.
"On the basis of this trial, I wouldn't say that women should not practice breast self-exam," he said. "Breast self-exam may be helpful for highly motivated women at high risk of breast cancer.
"However, our findings do show that investing in breast self-exam training programs is not a good use of cancer-prevention funds in developing countries without mammographic screening where public-health resources are limited.
"If we couldn't see a benefit in Shanghai, where we were able to devote enormous resources to the study of breast self-exam instruction, I doubt we would see a benefit in any other developing country."
Researchers also found that women who received intensive breast self-exam training experienced more benign breast biopsies, potentially adding to health-care costs.
"Not only did we find that breast self-exam instruction was not doing any good with respect to mortality, it has the added effect of burdening the health-care system," Thomas said.
The final results from the study, one of the largest of its kind, appear in the October issue of the Journal of the National Cancer Institute. Co-authors include Roberta Ray, Dr. Charlene Allison, Dr. Peggy Porter, Dr. Wenjin Li, Chunyuan Wu, Zakia Coriaty, Ilonka Evans, Dr. Ming Gang Lin and Dr. Steven Self of PHS, as well Dr. Dao Li Gao and other collaborators from the Station for The Prevention and Treatment of Cancer of the Shanghai Textile Industry Bureau.
Thomas and colleagues initiated the Shanghai study in 1988 to address conflicting reports over the value of breast self-exam. Unlike all but one prior study of breast self-exam, the Shanghai investigation was designed as a randomized trial, a type of study in which participants are randomly assigned to receive or not receive an intervention - in this case, intensive instruction in breast self-exam. Scientists consider randomized trials the "gold standard" of cancer-prevention research.
Women in 519 factories
Researchers randomly assigned 266,064 female textile workers in 519 factories in Shanghai to a breast self-exam instruction group or to a control group that did not receive breast self-exam instruction. The textile workers, none of whom received screening mammograms, obtained their primary medical care through factory clinics, which served as the sites for breast self-exam instruction.
Women in the self-exam instruction group were taught how to perform breast self-exam and took reinforcement classes one and three years later. The women also received regular reminders to practice breast self-exam monthly and practiced breast self-exam under medical supervision every six months for five years. The control group received no information on breast-cancer screening.
"The instruction was intensive," Thomas said. "Women were taught normal breast anatomy and how to identify lumps that are abnormal, and they practiced breast self-exams on silicone breast models as well as on themselves. At one of the reinforcement sessions, participants were also shown videos that demonstrated incorrect breast self-exam technique and were asked to identify the errors."
The researchers obtained information about breast cancer incidence and deaths among participants by periodically following up all women in the study, and from a Shanghai Textile Industry Bureau tumor and death registry and the Shanghai cancer registry.
After 10 to 11 years, there was no difference in breast-cancer mortality between the breast self-exam and control groups. There also was little evidence that cancers were detected at an earlier stage in the breast self-exam group.
However, women taught breast self-exam found more benign breast lesions than did women in the control group throughout the trial, an outcome that has serious implications for countries with limited health-care resources.
If any epidemiological trial could demonstrate the effectiveness of breast self-exam in a general population, the Shanghai trial had the best chance, Thomas said. No other breast self-exam study previously undertaken or already under way has involved such a large group of study participants previously unschooled in breast self-exam and so readily tracked, he said.
Test the highly motivated
Thomas said that studies are needed to determine whether women who are highly motivated to practice breast self-exam could enhance the benefit of a mammographic screening program by detecting cancers that occur between screenings.
The study authors noted that their recommendations for public-health officials and for individual women, particularly those at high risk for breast cancer, are distinct.
"For public-health officials who have to make choices about how to spend prevention funds, breast self-exam instruction programs are an idea that shouldn't be pursued," Thomas said. "Yet for a woman with a mother and sisters who have had breast cancer, it's a different story. You would not want to discourage these women from practicing breast self-exam."
Still, he added, "You'd have to inform them that they'd have to do a better job at it than women in our study and that it could increase their chances of undergoing a benign breast biopsy."
Don't abandon breast self-exam in the United States, caution clinicians
Developing nations without mammographic screening may not be well-served by intensive instruction in breast self-exam, but clinicians caution that U.S. women shouldn't be quick to abandon the practice.
"There's no doubt that (the Shanghai breast self-exam trial) was a very carefully controlled study," said Dr. Ben Anderson, director of the University of Washington Breast Care and Cancer Research Program and the Breast Cancer Specialty Center at the Seattle Cancer Care Alliance.
"But breast self-exam needs to be evaluated in conjunction with other screening techniques, such as breast imaging, that are common in the United States."
Anderson and Dr. Georgiana Ellis, a UW medical oncologist, noted that U.S. breast-cancer mortality rates have declined over the last decade.
"This is largely due to more aggressive therapy for patients with earlier-stage disease," Ellis said. "But it is difficult to argue that earlier diagnosis is playing no role, and it would be worrisome if this study served to discourage breast self-examination. I would estimate that a third to half of the women we see with breast cancer discovered the mass themselves, often through the breast self-exam."
The U.S. Preventive Health Services Task Force, an independent panel of experts that develops recommendations for clinical preventive services, currently recommends mammographic screening because it reduces breast-cancer mortality but does not recommend for or against the teaching of breast self-exam or practice of clinical breast examination due to insufficient evidence.
Dr. Connie Lehman, a UW radiologist and director of breast imaging at the Alliance, said that this lack of evidence is exactly why women should not be discouraged from practicing breast self-exam.
"Insufficient evidence doesn't mean don't do it. It just means we don't yet know," she said. "That's a difficult concept for women to appreciate. Failing to find evidence in support of breast self-exam is not the same as finding evidence against its practice."
She added that women should talk with their doctors about conducting breast self-exam.
"Women should be taught how to do breast self-exam by their doctors and informed of benefits and limitations," she said. "If they choose to do it after having this conversation, they should review their technique when they see their doctor. Not all breast self-exam is the same. It really matters how competently it is performed."