Clinical evaluation of ²⁵²Cf neutron intracavitary therapy for primary endometrial adenocarcinoma

Background. A pilot feasibility study of the neutron‐emitting radioisotope ²⁵²Cf was done on patients with uterine adenocarcinoma and medically inoperable disease or unfavorable G3 histologic findings. Methods. ²⁵²Cf intracavitary therapy was combined with 40–45 Gy of fractionated whole‐pelvis photon therapy. In select patients, hysterectomy was performed. Results. Thirty‐one patients with Stage I–III adenocarcinoma of the corpus uteri were treated with ²⁵²Cf neutron brachytherapy. The patients treated often were in poor general medical condition and had multiple chronic medical illnesses for which conventional radiation and surgery usually would not be recommended. ²⁵²Cf allowed short implant treatment time (hours), was usable in a small number of insertions (the average number of insertions was two), and was useful for treating large volume tumors. Stage and grade of the tumor were important determinants of patient survival. The 5‐year actuarial survival was 83% for patients with Stage I disease but only 37% for those with Stage II disease (primarily adenosquamous cell carcinomas). The 5‐year survival was 100% for patients with Grade 1 tumors, 88% for those with Grade 2 tumors, and 21% for those with Grade 3 tumors. Conclusion. ²⁵²Cf neutron brachytherapy was found to be an effective and well‐tolerated therapy for endometrial carcinoma. The excellent therapeutic efficacy and good patient tolerance make it suitable for additional evaluation in future Phase II‐III trials.