Changes of the DNA content of cell nuclei in mucosa and carcinoma of the rectum after application of different methods of the preoperative irradiation

Microspectrophotometric investigation of the DNA content of cell nuclei in normal mucosa and carcinoma of the rectum was performed in 47 patients before and after irradiation with doses of 20 Gy, 40 Gy, and 36 Gy plus 7 g 5-fluorouracil. Pretreatment biopsy and surgical specimens were used for the investigation. It was observed that the normal mucosa contains a homogeneous cell population with diploid DNA values. Rectal adenocarcinoma is characterized by polyploidy, augmentation of the 'DNA accumulation index' that continues to rise if the degree of differentiation decreases. After radiotherapy and combined chemo- plus radiotherapy the rectal mucosa showed signs of polyploidy and increase of the 'index of DNA accumulation'. Irradiation caused a considerable poly- and heteroploidy of cell nuclei in rectal adenocarcinomas. (author)