Major Study in Shanghai Looks at Efficacy of Breast Self-examination
David B. Thomas
Breast cancer is the most common malignancy in women in the developed countries of the world. In many economically disadvantaged countries breast cancer rates have been low, but in areas undergoing economic and cultural transformations to a more "Western" way of life, this disease is rapidly increasing in importance. Although epidemiologists have identified several risk factors, such as early menarche, late menopause, nulliparity or late childbearing, a history of benign breast lesions with ductal proliferation, and a family history of breast cancer, there are no practical means to modify these or any other factors to reduce a woman's risk of developing breast cancer. Mammography, with and without clinical breast examination by a health practitioner, is effective in reducing mortality by about 30% in women over 50 years of age. However, mammography is too expensive to be widely used in much of the developing world. Furthermore, even in wealthy populations, screening women more than once a year is not practical; and some cancers that develop between annual screenings can progress to such an extent that they are not amenable to curative treatment. This phenomenon, plus the inability of mammography to detect all existing tumors at an early stage, probably explains the rather small effect of mammography on breast cancer mortality.
Breast self-examination (BSE) has theoretical advantages over mammography and manual palpation by a practitioner. If practiced regularly and frequently, it may be of value in detecting interval cancers, and it may be more sensitive than a clinical breast examination because women may be able to detect subtle changes in their breasts that would be missed on manual palpation by others. BSE may thus be a useful adjunct to annual screenings. In addition, it is cheap and could be of practical use in countries where mammography is not affordable, if it is shown to be efficacious.
BSE has been widely advocated by many organizations and individuals, but studies conducted to date have not provided valid or consistent evidence for its efficacy In 1995, the U.S. Preventive Health Services Task Force concluded that evidence is insufficient to recommend for or against the teaching of BSE. Expert committees of both the World Health Organization (WHO) and the International Union Against Cancers have advocated randomized trials to determine whether the regular practice of BSE can reduce mortality from breast cancer. Such a trial began in the 1980s in Russia, but the disintegration of the Soviet Union disrupted the project so much that it is not likely to produce useful information. Beginning in 1988 in Shanghai, China, a randomized trial of BSE was initiated by the Fred Hutchinson Cancer Research Center (FHCRC through a grant funded by the National Cancer Institute.
Study Methods
The study is being conducted in the Shanghai Textile Industry Bureau under the direction of Dr. Gao Dao Li, a former visiting scientist in the Department of Epidemiology in the University of Washington School of Public Health and Community Medicine. When the study began, this bureau included 520 factories employing over 300,000 women. Under the Chinese socialist system, women were assigned to a work unit on entering the work force and infrequently transferred to other units. Most women received their primary medical care through medical clinics in each factory. Upon retiring, women continued to receive their medical benefits, pensions, and other benefits through their factory. This system provided an almost ideal environment for this trial.A team of 34 retired factory medical workers, referred to as BSE workers, are implementing the trial with the assistance of approximately 5,000 factory medical workers, plus 10 additional office and supervisory staff. All study protocols, manuals, and forms are developed by a study team in Seattle, translated into Chinese, pilot tested in Shanghai, and modified if needed before use. Data are recorded in Shanghai and transmitted on diskette to Seattle to be edited and analyzed.
The 520 factories were randomly allocated to the instruction or control group. All current or retired employees without a history of breast cancer who were born between 1925 and 1958 were eligible. Of the 267,040 women enrolled in the trial, 133,375 were in the instruction group.
Jan Mahloch, a member of the project team from the Fred Hutchinson Cancer Research Center, uses a silicone breast model to teach proper palpation techniques to the BSE workers who are instructing study participants.
From October 1989 to October 1991 a baseline questionnaire was administered to obtain information on risk factors for breast cancer. The BSE workers instructed women in groups of approximately 10. They used multiple visual aids to present information on the normal anatomy of the breast, breast cancer, the importance of early detection, and correct BSE techniques. Silicone breast models were used to teach proper palpation technique, and all sessions ended with supervised practice of the women performing BSE on themselves. From completion of baseline activities in 1991 through mid-1995, women were encouraged to come to their factory clinics approximately twice each year for supervised practice of BSE. During two reinforcement sessions at one year after initial instruction, and again in 1993-95, the women saw two videos and practiced BSE.
The program also used posters (Figure 1) and other reminders and inducements to practice.
Figure 1: Instructional posters helped to remind study participants of BSE techniques. Below are the characters for breast self-examination.
All women in the study are followed by periodic visits to factories by the BSE workers, and through attendance at the supervised BSE and reinforcement sessions; those who move from Shanghai or die are identified. Women who develop a breast lump are initially evaluated by factory medical workers, and then by a surgeon if warranted. If a lump is biopsied, the study workers collect information on its histology (benign or malignant), size, and location in the breast. Annual follow-ups determine survival of women with breast cancer. An advisory committee to the study, known as a "leading group," was established when the study began. The chair of this group is the deputy director of the Textile Bureau's Department of Education and Health and is responsible for all factory medical clinics. Other committee members include the directors and deputy directors of the three Textile Bureau hospitals. This group serves as the local decision-making body for the trial, and as the Institutional Review Board (IRB). It approves all procedures prior to their implementation, and periodically reviews progress of the trial with study investigators.
Cultural characteristics of contemporary urban Chinese women have proven to be both beneficial and a challenge to implementation of this project. The socialist system emphasized group decision making following discussion of issues. At the same time, people were expected to assume responsibility for their own activities; hence the title of one of our videos and the slogan for the study became "Protect your own health with your own hands." These attributes of modern Chinese society facilitated acceptance and implementation of the group method of providing BSE instruction. However, modesty is also a valued and highly prevalent attribute; and even though bathing in communal showers is the norm, practicing BSE in a group setting and inspecting one's breasts in a mirror were initially met with some resistance. This reluctance was only overcome after instruction group discussions focused on these issues and, for some women, identified specific means to ensure privacy while practicing BSE.
Recent economic reforms in China have also complicated implementation of the trial. Some factories have merged with others or closed, and some women have transferred from their original factory, gone to work in the private sector, or moved from Shanghai. However, these changes have affected a relatively small proportion of the study population, and they occurred largely after the primary BSE instruction efforts were completed. Still, as more factories are affected by these changes, future follow-up activities will become more difficult, and new methods to ensure completeness of follow-up will have to be developed.
Preliminary Results
For this trial to provide a valid assessment of the efficacy of BSE, the women must show high level of compliance with study procedures and achieve competency in practicing BSE. We have evidence that both of these goals were achieved. Available data on half of the instruction group show that 84% of the women attended the initial baseline BSE instruction and the two reinforcement sessions. Also, of the more than 1. 17 million individual sessions for supervised BSE that were scheduled through 1994, 87% were attended.Compared to sampled women in the control group, a higher proportion of the instruction groups found lumps in test breast models, and a smaller proportion erroneously reported detection of lumps that did not exist. These results suggest that BSE instruction achieved an increase in both sensitivity and specificity for lump detection in practice.
As expected, through 1994, approximately equal numbers of breast cancers occurred in the two arms of the study: 331 in the instruction group and 322 in the control group. However, about three times as many benign lesions were detected in the instruction group, which indicates a higher level of suspicion in the women who received the BSE instruction. Unexpectedly, however, the breast malignancies in the instruction group were not detected when smaller or at a less advanced stage than those in the control group. A possible explanation is that the information on stage and tumor size may be imprecise because it was obtained from medical records from multiple institutions, and no attempt to standardize staging or measurement of lesions was possible.
The total mortality rate through 1994 was nearly the same in the instruction and control groups (1. 1 and 1. 2 %, respectively). The cumulative breast cancer mortality rate was also nearly the same in the two groups. This result is not unexpected. In randomized trials of mammography, a difference in breast cancer mortality between the screened and unscreened groups of women of comparable age did not begin to emerge until the fifth year after randomization.
These preliminary results were published in the Journal of the National Cancer Institute.
Implications and Future Plans
The women in this study will be followed for 10 years. The efficacy of BSE in reducing mortality from breast cancer will not be known until 2001. Beneficial results will justify programs to teach women BSE and motivate them to practice. Conversely, if a reduction in breast cancer mortality rates is not detected in the instruction group, then we will be able to indicate the level of BSE practice activity that must be exceeded for a program to have a chance of improving breast cancer mortality This level of activity is high, thus, a negative result will suggest that public health resources should not be spent on BSE instruction programs.To our knowledge, this is the only randomized trial of BSE now in progress in the world. We believe it unlikely that additional information will become available before it is completed and thus predict no change in the opinion of the U.S. Preventive Health Services Task Force that information to recommend for or against the teaching of BSE is insufficient.
This study population has provided a rich resource for additional epidemiologic studies of possible causes of breast cancer. Dr. Steven Self, head of the program in biostatistics at the Fred Hutchinson Cancer Research Center and professor of biostatistics at the UW School of Public Health and Community Medicine, is the principal investigator for an independently funded grant from the National Cancer Institute that supports a study of genetic, hormonal, and environmental determinants of cell proliferation in benign and malignant breast tumor tissue and in adjacent normal tissue. Dr. David Hockenbery, also of the FHCRC and assistant professor in the Department of Medicine at the University of Washington, has added a study of the determinants of cell death (apoptosis) to this investigation.
Additional NCI-funded ancillary investigations in progress include a study of nutritional factors in the etiology of breast cancer and a study of the possible role of induced abortion in the development of breast cancer, which is being conducted by a doctoral student in the Department of Epidemiology, Ye Zhan. The FHCRC has provided pilot funding for a genetic study that compares white blood cells from women with breast cancer and from a sample of normal women in the study population. Dr. Elaine Ostrander recently received grant funding to support a formal study.
The grant that funds the BSE trial has been renewed for an additional five years, and we anticipate that between now and its termination in 2002 it will provide opportunities for additional joint projects between faculty and students associated with the School of Public Health and Community Medicine and colleagues in Shanghai.
Recommended Reading
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Miller AB, Baines Q, To T, Wall C: Canadian national breast screening study: 1. Breast cancer detection and death rates among women aged 40 to 49 years. Can Med Assoc J 1992; 147:1459-1476. Miller AB, Baines Q, To T, Wall C: Canadian nationatal breast screening study: 2. Breast cancer detection and death rates among women aged 50 to 59 years. Can Med Assoc J 1992; 147:1477-1488.
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Thomas DB, Gao DL, Self SG, et al: A randomized trial of breast self-examination in Shanghai: Methodology and preliminary results. J Natl Cancer Inst 199-1 , 89:355-65.Author
David B. Thomas, M.D., Dr PH., is head of the Program in Epidemiology at the Fred Hutchinson Cancer Research Center, and professor of epidemiology at the UW School of Public Health and Community Medicine. He is the principal investigator of the Shanghai BSE study.
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Created: 2/6/98 Updated: 7/15/99
