[Success and apparent success resulting from early cancer diagnosis (author's transl)].

Cancer screening techniques are of great value in improving the results of treatment of various tumours. Unfortunately screening and early diagnosis of cancers does not improve the prognosis in every case. Early diagnosis may lead to an apparent success without affecting the final outcome of treatment. Early diagnosis may even be harmful to the patient if the diagnostic and therapeutic methods lead to dissemination of the tumour, as has been shown by a number of authors. Consequently cancer screening and early diagnosis should be confined to those selected tumours which are not affected adversely by diagnostic methods.