Californium-252 neutron curietherapy for advanced cervical cancer

Low dose rate neutron radiotherapy using fast neutrons emitted by the radionuclide 252Cf was combined with fractionated X- or gamma rays for the radiotherapy of advanced cervicovaginal tumors. Two different implant schedules were tested to determine the response of the tumors to the scheduling of therapy with the 252CF either early or delayed in the fractionated radiotherapy course. A 90% frequency of complete local clearance of pelvic tumors was observed by the early application of 252Cf. Neutron curietherapy applied as a boost treatment at the end of fractionated radiotherapy, resulted in only 40% local control. Improved results were observed by early implantation therapy and is postulated to be the result of more effective hypoxic tumor therapy and reoxygenation of the hypoxic pelvic tumor. The two groups of patients were compared as to their general status and medical condition and were found similar in age, frequency of associated disease, body weight and tumor stage. The failures of local control by early 252Cf neutron therapy, occurred in 2 patients with high-stage tumor and severe vascular disease and suggests that tumor response was partly dependent upon the integrity and elasticity of the small vessel system.