Current practice of breast cancer detection
Breast cancer detection currently entails three distinct stages. The first stage is identification of an abnormality in the breast tissue either by physical examination or by an imaging technique (most commonly, mammography). Once identified, the abnormality must be diagnosed as benign or malignant by using additional imaging modalities or by biopsy and microscopic examination of the tissue morphology (Figure 1-4).
In the third stage, abnormalities labeled as malignant must be further characterized biochemically and staged according to tumor size and extent of invasion and metastasis to determine a prognosis and an appropriate course of treatment.
Monthly breast self-examination (BSE) is a common method of identifying lumps and other abnormalities in the breast. BSE in conjunction with screening mammography is currently advocated by many organizations, but it is also recommended for younger women who are not yet being screened by mammography. BSE was first advocated in the 1940s and 1950s, before the advent of screening mammography. Breast surgeons saw many patients whose tumors were too large for surgical removal, and they believed that regular self-examination of the breasts would result in earlier detection when surgery was still an option.
Although the goal of finding smaller tumors at an earlier stage may be attained by BSE (Coleman, 1991), to date the evidence is not definitive that BSE improves the survival rate for women with breast cancer. Furthermore, BSE can lead to an increase in unnecessary biopsies, especially in younger women (Semiglazov et al., 1992, 1999; Thomas et al., 1997).
Two large, randomized trials are ongoing in Russia and China and may help to answer some of these questions more definitively.
FIGURE 1-4 Breast cancer management algorithm. SOURCE: Risk Management Foundation, Boston Massachusetts (May 23, 2000).
FIGURE 1-4 (Continued)Breast cancer management algorithm. SOURCE: Risk Management Foundation, Boston Massachusetts (May 23, 2000).
Breast physical examination by physicians is also widely practiced and advocated for women of all ages. Although clinical breast examination (CBE) has been studied in conjunction with mammography and one study has shown it to be beneficial in that context (the Health Insurance Plan of New York [HIP] trial), its use as a stand-alone screening tool has not yet been fully assessed. A large trial is being undertaken in India to determine the impact of screening by physical examination alone on breast cancer mortality (Jatoi, 1999). In Canada, a large randomized clinical trial has directly compared CBE alone with screening mammography plus CBE. The results showed no significant difference in breast cancer mortality rates between the two study arms at 7 and 13 years after the initiation of screening (Miller et al., 1993, 2000), although mammography identified smaller tumors than physical examination did. The study does not question the assertion that mammography lowers breast cancer mortality, but the results suggest that a very careful standardized physical examination (lasting an average of 10 minutes) can achieve the same reduction in mortality as screening mammography. The investigators in that study did not address the question of whether mammography led to reduced morbidity as a result of less aggressive treatment for the smaller tumors found by that screening approach. This is the only study to date to directly compare CBE to screening mammography, so there are no data to confirm or refute the findings, although the undertaking of such a confirmatory study has recently been suggested (Mittra et al., 2000). However, even if the data are sound, it might be more difficult in practice to recapitulate the benefits of CBE observed in this clinical trial (that is, more difficult than it would be for mammography) because mammography is highly standardized and regulated in the United States (see the discussion of the Mammography Quality Standards Act below), whereas CBE is not. A number of recommendations for improving the practice and standardization of CBE have been made based on a review of the literature (Barton et al., 1999).
Nevertheless, physical examination will always be important, but it is not sensitive enough to identify very small tumors. Although a pad to help women perform BSE was recently approved by the FDA and some electronic palpation devices are under development, prospects for improving physical detection methods may depend more on increasing the number of people who do it carefully and thoroughly after training and education than on technological advances.