Californium-252 (252Cf) versus conventional gamma radiation in the brachytherapy of advanced cervical carcinoma long-term treatment results of a randomized study.

Background: When photon radiotherapy is applied to cervical carcinoma, it has been observed that, despite important progress in radiotherapy technique and quality assurance, no significant increase in curative rates has resulted. Among the reasons for this is the varying radiosensitivity of different tumor subpopulations. Treatment with californium-252 ( 252 Cf), as a source of gamma/ neutron radiation in brachytherapy, provides properties and new treatment modalities that help to overcome this factor. Patients and Methods: From January 1985 to June 1993, 227 women with stage IIB and IIIB cervical carcinoma were treated in a randomized brachytherapy study as follows: (1) 117 patients (55 with stage IIB, 62 with stage IIIB) were treated with 252 Cf during the 1st week of therapy by 6 Gy (40 Gy-eq) of the neutron component in point A. Supplementation by a 16-Gy dose with 226 Ra or 137 Cs was done in the 5th week, (2) 110 patients (50 with stage IIB, 60 with stage IIIB) were treated solely by gamma radiation ( 226 Ra or 137 Cs). A dose of 56 Gy in point A was applied in two fractions at the 3rd and 5th week, respectively. The dose of 56 Gy-equivalents was completed by external radiation with 40 Gy. The total radiation doses at points A and B amounted to 85 Gy and 59 Gy, respectively. The treatment results were compared. Results: The overall 5-year survival rate for all stages IIB and IIIB was better by 18.9% for 252 Cf patients than for patients receiving conventional treatment (75.2% vs. 56.3%, respectively; p < 0.001). In the stage IIIB 252 Cf group, it was significantly better by 22.8% than for the conventional group (66.1% vs. 43.3%, respectively; p < 0.003). The higher survival rate in 252 Cf patients was the result of significantly less local relapses compared with patients treated conventionally (12,8% vs. 31.8%; p < 0.0009). Conclusion: The importance of neutron source 252 Cf in the brachytherapy of cervical carcinoma by overcoming the tumor resistance to conventional photon irradiation has been confirmed.