[DNA cytophotometry and diagnosis of malignant tumours (author's transl)]

By means of an integrating scanning microspectrophotometer the extinction of Feulgen-stained histological sections from normal and neoplastic epithelia (skin, larynx, cervix, stomach, colon and endometrium) was measured. The extinction was multiplied with the nucleus area area to get arbitrary units being a relative measure of the DNA content of the nuclei (small lymphocytes were used as diploid standard). A new parameter, the "DNA accumulation index", is introduced (mean value of the cell numbers multiplied with the degrees of ploidy). The results of 652 observations demonstrate the exponential character of the DNA increase in proliferating and neoplastic cells. In precancerous lesions a doubling of the DNA accumulation index was observed whereas in malignant neoplasias a second doubling of the DNA content takes place. The method is recommended for the diagnosis of neoplastic alterations in epithelia.