Toward four-dimensional image-guided adaptive brachytherapy in locally recurrent endometrial cancer.

Abstract

To evaluate clinical outcome and feasibility of a four-dimensional image-guided adaptive brachytherapy concept in patients with locally recurrent endometrial cancer. Forty-three patients with locally recurrent endometrial cancer were included. Treatment consisted of conformal external beam radiotherapy followed by a boost using pulsed-dose-rate brachytherapy (BT). Large tumors were treated with MRI-guided interstitial BT. Small tumors were treated with CT-guided intracavitary BT. The planning aim (total external beam radiotherapy and BT) for high-risk clinical target volume was D90>80Gy, whereas constraints for organs at risk were D2cc≤90Gy for bladder and D2cc≤70Gy for rectum, sigmoid, and bowel in terms of equivalent dose in 2Gy fractions. Median high-risk clinical target volume was 18cm(3) (range, 0-91). D90 was 82Gy (range, 77-88). D2cc to bladder, rectum, and sigmoid were 67Gy (range, 50-81), 67Gy (range, 51-77), and 55Gy (range, 44-68), respectively. Median followup was 30months (6-88). Two-year local control rate was 92% (standard error [SE], 5). Disease-free survival rate and overall survival rate was 59% (SE, 8) and 78% (SE, 7), respectively. Patients with low- to intermediate-risk for recurrence had a 2-year disease-free survival rate of 72% (SE, 9) compared with 42% (SE, 12) in patients with high risk for recurrence (p=0.04). Late morbidity Grade 3 was recorded in 5 (12%) patients. Four-dimensional image-guided adaptive brachytherapy is feasible in locally recurrent endometrial cancer. Local control rate is good. Systemic control remains a problem in patients with high risk for recurrence.