Abstract
Ideally, a measurable product of cancer cells that is shed in blood or urine would permit objective assessment of residual microscopic tumor deposits and simplify decisions about adjuvant therapy. Because the overall effects of most individual trials, particularly on survival, have been small and because of the great interest in analyses of subgroups (classified, for example, according to menopausal status and nodal status), relatively large numbers of patients are required to observe small but clinically important effects. A major area of clinical investigation is the use of more intensive chemotherapy regimens as adjuvant therapy. Since bone marrow is the dose-limiting tissue for most chemotherapeutic agents, more intensive chemotherapy regimens followed by transplantation of autologous bone marrow have recently been developed. The term "retinoids" applies to vitamin A (retinol) and its isomers, derivatives, and synthetic analogues. Since retinoids are biologic regulators of orderly epithelial-cell development, they are potentially ideal agents for controlling abnormal epithelial proliferation, such as occurs in carcinogenesis. [...]although the identification of specific genetic abnormalities will undoubtedly be of value in counseling and will improve the specificity of screening and the rate of early detection, it may also present new psychological, ethical, and legal problems.255 Conclusions The incidence of breast cancer is increasing in the United States, and the factors responsible for this increase remain uncertain.
