Ovarian ablation by radiotherapy; is it still an option for the ovarian function suppression in endocrine responsive premenopausal breast cancer patients?.

Abstract

Abstract Abstract #5137 Background; Although surgical or medical ovarian ablation is likely to be the treatment of choice at the current time, radiation ablation (RA) can be still a resonable alternative. Data regarding the use of pelvic radiotherapy (RT) for ovarian ablation is very limited and in 10thSt Gallen consensus meeting, ovarian radiation was overwhelmingly rejected. In this retrospective study we evaluated the efficacy of RT for ovarian function suppression in 118 premenopausal breast cancer patients.
 Materials and Methods; 153 breast cancer patients had RA between the years 1979 and 2002 at the single center where this study was performed. 19 patients who received chemotherapy within 12 months of RA, and 16 patients who were lost to follow-up within 6 months following RA, were not included into the analyses. All patients were premenopausal and the median age at the initiation of RA was 39 years (range, 21- 52 years). 96 of 118 patients (82%) underwent RA for metastatic disease, 17 patients (14%) received RA as the systemic treatment after locoregional recurrences and 5 patients (4%) had RA as an adjuvant treatment. 97 patients (82%) received only RA as their systemic treatment, 20 patients (17%) had RA with tamoxifen and one patient (1%) had RA with aromatase inhibitors. RT was given with either Co-60 or 15 MV photons of the linear accelerator. A modified pelvic volume was irradiated with opposing anterior and posterior fields, and the dose was prescribed to midplane. The median total dose used for RA was 15Gy in 4 fractions (range 5Gy single fraction-36Gy in 18 fractions).
 Results; As the efficacy of RA, data regarding the menstrual status were collected. Amenorrhea was noted in 113 of 118 patients (96%) in 6 months following RA. 88 patients (75%) experienced amenorrhea in 2 months after pelvic RT. 5 patients (4%) who had still normal menstrual functioning after 6 months of RA had estrodiol and follicle stimulating hormone measurements. As they were found to have premenopausal levels, 3 of them received surgical and 2 of them received medical ablation. No acute Grade 3 or 4 (according to the Radiation Therapy Oncology Group radiation morbidity scoring criteria) toxicities were noted. With a median follow-up of 24,5 months (range; 6-167 months), no late severe complications that could be attributable to RT were reported. The total RT dose (more than 15Gy) were found to be significant on the rate of ovarian ablation with Mann Whithney U-test (p=0.02).
 Conclusion: Ovarian ablation was achieved with a rate of 96% without any major acute and late toxicity using pelvic RT. It should be considered as an option for endocrine responsive premenopausal breast cancer patients and can be easily delivered when postoperative or palliative irradiation is given. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5137.