Second re-irradiation: Efficacy, dose and toxicity in patients who received three courses of radiotherapy with overlapping fields

Abstract

Purpose To explore the outcome, cumulative dose and toxicity in 23 patients after a third radiation treatment, with a partial or complete overlap of the previous two irradiated regions. Methods and material The dose summation of the three radiation plans was made by the planning system. For patients treated with cyberknife or brachytherapy dose summation was done by dose point calculations. Efficacy and toxicity was scored by looking at the reduction of tumor, pain and bleeding. Results Symptomatic response was observed in 81% and 73% of the patients after, respectively, the third and second radiation. The median cumulative maximum dose to the tumor and its regions was 133 Gy 3 (range: 82–496 Gy 3). The median corrected cumulative dose for the rectum, bowel and bladder resulted in 91 Gy 3, 73 Gy 3 and 79 Gy 3, respectively. Grade 3 acute skin toxicity was only seen in the third radiation course. Conclusion The constraints of 100 Gy 3 for rectum, 90 Gy 3 for bowel and 110 Gy 3 for bladder are safe and can be used as guidelines in the decision for re-irradiation. Symptomatic relieve was seen in 81% of the patients with low grade 3 and no grade 4 acute and late toxicity.