Changes of the DNA content of cell nuclei in mucosa and carcinoma of the rectum after replication 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 an 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 radiation therapy and combined chemo- plus radiationtherapy the rectal mucosa shows signs of polyploidy and increase of the "index of DNA accumulation". Irradiation causes a considerable poly- and heteroploidy of cell nuclei in rectal adenocarcinomas.