E. GRUNDMANN The question as to whether cytostatic drugs might be carcinogenic has been presented and discussed in three experimental studies. The most extensive in- vestigations were by J. H. WEISBURGER and coll. (New York, Alabama, Bethesda). They started with an exact determination of rate and localization for spon- . taneous tumors in their animal strains. Thirteen cytostatic compounds current- ly in clinical use were then given in the maximally tolerated dose (MTD) to groups of 25 male and 25 female animals (rats and mice) three times weekly, in most assays over a period of 6 months. Other identical groups of animals received 0. 5 of the MTD. Each test involved 50 male and 50 female mice and the same number of rats. As positive controls, identical groups were given diethylnitrosamine, which induced tumors of liver, lungs and kidneys in the expected rates. The direct alkylating agents (Actinomycin 0, Melphalan, Mito- mycin 0, Uracil mustard, Dibromomannitol and Dibromodulcitol) induced cancer in the peritoneal cavity, the site of the injections. Rats appeared to be more susceptible than mice. Other drugs (e. g. the cyclohexamide salt of phos- phorodiamidic acid derivative, Natulan, DIC and streptozotocin) had a broad spectrum of carcinogenicity affecting a variety of organs. Several agents led to tumors in the hematopoietic and lymphatic systems in mice or rats or both. The correlation to the general immunosuppressive action is not quite clear. 6-Mercaptopurine induces lymphosarcomas in mice.

The growth and function of many tissues are influenced by hormones. Therefore it is quite understandable that hormones play a role in the development and treatment of malignant tumors. Numerous publications address this topic; however, the results of many studies are controversial and have not been unequivocally accepted. For nearly 50 years the carcinogenic effect of steroid hormones has been under debate, and their therapeutic value a matter of discussion for equally as long. The present volume concentrates on substantiated data first obtained from the study of tumors developing from hormone regulated or hormone-producing tissue, e.g., the thyroid, adrenal glands, prostate, and the female genital tract. Through a joint approach from the field of molecular biology, biochemistry, and histopathology, advances in the management of these tumors have been elaborated. Another exciting example is the endo nuclear diagnosis of adrenal tumors. Antihormones, i.e. antian drogens or GnRH analogues have proved to be important indeed since they exhibit a destructive effect on prostate carcinomas and breast cancer. Further improvements can be expected in the localization of hormones in tumor tissue by specific antibodies. A special chapter is dedicated to the diffuse endocrine cell system (DECS), the clinical significance of which has mainly become obvious in the gastroenteropancreatic tract.

Minimal neoplasia may be defined as a small cancer that has progressed beyond its site of primary origin into the surrounding tissue, but that has not yet reached the stage of deeper invasion or metastasization. The basic principles of this minimal cancer are presented in chapters on molecular, biological and experimental aspects, and, in particular, on the clinical manifestations in various organs: preleukemia, incipient lymphoma, and minimal carcinomas of the uterine cervix, breast, thyroid, larynx, lung, prostate, stomach and colon. A separate chapter is devoted to cryptic gliomas. The latest morphological methods including cytology, early clinical diagnostics and, in particular, radiodiagnostics, are considered. The reader can expect up-to-date information about prompt diagnosis of the very early manifestations of cancer, together with inferences on therapy, which, especially in tumors of the uterine cervix, breast and thyroid, differs considerably from the treatment of advanced neoplasia.

The preceding decade has seen the production of many cancer at lases. As with other techniques of descriptive epidemiology, these atlases have proved valuable in identifying areas for further re sear~h employing the methods of analytical epidemiology. How ever, the various cancer atlases produceq to date have failed to pro vide a common format of presentation, which has limited their comparability and frustrated in a large measure any attempt to compare risks across national boundaries, boundaries which in terms of environmental exposures may have little meaning. In this volume, many features of cancer atlases are presented and there are discussions on the areas where moves towards standardization could greatly increase the utility of the finished product. In contrast to topographic maps, i. e., representations of natural and man-made features on the surface of the earth, thematic maps concentrate on displaying the geographical occurrence and varia tion of a single phenomenon - the "theme" of the map. The link between thematic and base mapping is rather strong as the themat ic information to be depicted is of greater value if displayed on an accurate base map. Further, the thematic map generally uses statis tical data which are frequently related to internal administrative boundaries for enumeration. The major reason for constructing a thematic map is to discover the spatial structure of the theme of the map and to then relate the structure to some aspects of the under lying environment.