Transperineal high-dose-rate interstitial radiation therapy in the management of gynecologic malignancies

Background: High-close-rate interstitial radiation therapy is a newly introduced modality, and its role in the management of gynecologic malignancies remains to be studied. Clinical experience in high-close-rate interstitial radiation therapy was retrospectively investigated. Patients and Methods: Eight patients with primary and nine with recurrent gynecologic malignancies underwent high-close-rate interstitial radiation therapy with/without external-beam irradiation. Fractional dose of the high-close-rate interstitial radiation therapy ranged between 4 and 6 Gy with total doses of 15-54 Gy. Interstitial irradiation was performed twice daily with an interval of > 6 h. Results: 2-year local control rate was 75% for primary treatment and 47% for treatment of recurrence (p = 0.46). Maximum tumor size had a statistically significant impact on local control (p < 0.002). Grade 2 and 4 Late complications were seen in five patients, and the incidence was significantly higher in patients with a Larger volume enclosed by the prescribed fractional dose of high-dose-rate interstitial radiation therapy. The incidence of grade 2 and 4 complications at 18 months was 78% and 0% with a volume > 100 cm(3) and less than or equal to 100 cm(3), respectively (p < 0.04). Conclusion: Although high-dose-rate interstitial radiation therapy is a promising modality, it must be applied cautiously to patients with bulky tumors because of the high incidence of serious complications.