Iridium-192 transperineal interstitial brachytherapy for locally advanced or recurrent gynecological malignancies

Abstract

Purpose: To assess treatment outcome for patients with locally advanced or recurrent gynecological malignancies treated with continuous low-dose-rate (LDR) remote afterloading brachytherapy using the Martinez Universal Perineal Interstitial Template (MUPIT).

Materials and methods: Between 7/85 and 6/94, 69 patients with either locally advanced or recurrent malignancies of the cervix, endometrium, vagina, or female urethra were treated by 5 different physicians using the MUPIT with (24 patients) or without (45 patients) interstitial hyperthermia. Fifty-four patients had no prior treatment with radiation and received a combination of external beam irradiation (EBRT) and an interstitial implant. The combined median dose was 71 Gy (range 56-99 Gy), median EBRT dose was 39 Gy (range 30-74 Gy), and the median implant dose was 32 Gy (range 17-40 Gy). Fifteen patients with prior radiation treatment received an implant alone. The total median dose including previous EBRT was 91 Gy (range 70-130 Gy) and the median implant dose was 35 Gy (range 25-55 Gy).

Results: With a median follow-up of 4.7 yr in survivors, the 3-yr actuarial local control (LC), disease-specific survival (DSS), and overall survival (OS) for all patients was 60%, 55%, and 41% respectively. The clinical complete response rate was 78% and in these patients the 3-year actuarial LC, DSS, and OS was 78%, 79%, and 63% respectively. On univariate analysis for local control, disease volume and hemoglobin were found to be statistically significant. On multivariate analysis, however, only disease volume remained significant (p = 0.011). There was no statistically significant difference in local control whether patients had received any prior treatment with radiation (p = 0.34), had recurrent disease (p = 0.13), or which physician performed the implant (p = 0.45). The grade 4 complication rate (small bowel obstruction requiring surgery, fistulas, soft tissue necrosis) for all patients was 14%. With a dose rate less than 70 cGy/hour, the grade 4 complication rate was 3% vs. 24% with dose rate > or = 70 cGy/hour (p = 0.013).

Conclusion: Patients with locally advanced or recurrent gynecological malignancies treated with the remote afterloader LDR MUPIT applicator can expect reasonable rates of local control that are not operator-dependent. Complication rates with this approach are acceptable and appear to be related to the dose rate.