EARLY CHANGES IN FLOW CYTOMETRIC DNA PROFILES INDUCED BY CF-252 NEUTRON BRACHYTHERAPY IN SQUAMOCELLULAR CARCINOMAS OF THE UTERINE CERVIX

Ninety-five squamocellular carcinomas of the uterine cervix, clinical Stages II and III, were treated by either four schedules combining 252 -californium neutron-gamma-radiotherapy with different proportions of a neutron component (9, 6 and 3 Gy) or gamma-irradiation alone. Flow c ytometric DNA profiles were obtainable in 72 cases before treatment an d 56 cases were monitored for DNA content by flow cytometry (FCM) in w eekly intervals by analysis of sequential microbiopsies for one month during and after radiotherapy. DNA aneuploidy was reduced from 40% (25 /63) to 19% (9/47) one week within therapy in neutron-treated groups, but not after initial gamma-radiotherapy alone. Extinction of DNA aneu ploid subpopulations occurred after neutron therapy in all remaining a neuploid tumors (9/9) during further monitoring, but only in 40% (2/5) of tumors after sole gamma-irradiation. In contrast, proliferation in dex by more than 50% was more often achieved in groups with a higher g amma-radiation component than after neutrons only. When all therapy-in duced DNA flow cytometric events are taken together for evaluation of the effects of various radiotherapy schedules, it appears that the reg imen with the maximal neutron dose may not be optimal for all tumors. It is hypothesized that the differences in the early flow cytometric D NA profiles may select the DNA aneuploid squamous cell uterine cervica l carcinomas as candidates for combined neutron-brachytherapy, while h ighly proliferating DNA near-diploid tumors may profit more from treat ment with a higher gamma-radiotherapy component. However, these early DNA flow cytometric findings need to be correlated with clinical cours e of the disease to validate this hypothesis, a process which will be completed at the end of the expected five-year clinical outcome in 200 0.