Single 4 Gy re-irradiation for painful bone metastasis following single fraction radiotherapy

Purpose: to investigate effectiveness of a single-fraction of 4 Gy given for re-treatment of bone metastasis after previous single-fraction radiotherapy (RT). Material and Methods: Of 135 patients retreated, 109 patients were retreated because of pain relapsing after 4 Gy (group I, n = 34), 6 Gy (group II, n = 39), or 8 Gy (group III, n = 36), while 26 patients were re-irradiated after initial non-response (group I, n = 12; group II, n = 8; group III, n = 6). Results: Of the 109 patients that were re-irradiated for pain relapse, 80 (74%) patients responded (complete response (CR) = 31%;partial response PR) = 42%). Among the 26 patients that initially did not respond, there were 12 (46%) responses. Patients with previous CR were more likely to achieve CR than were patients with previous PR (P = 0.042). No such finding was observed for obtaining PR, which was achieved in 45% each of patients previously having either CR or PR (P = 0.99). Patients with previous CR had similar chance to obtain either CR or PR (P = 0.65), while previous PR influenced subsequent response in the way of achieving more PRs than CRs (P = 0.00054). Combined, these data showed that patients with initial CR were more likely to respond than those with previous PR (85% vs. 67%, P = 0.037), There were no difference between the three initial treatment groups regarding the efficiency (CR or CR + PR) of second RT. Toxicity was low and only gastrointestinal. Conclusions: Single-fraction RT consisting of 4 Gy was effective and little toxic treatment that could be administered after previous single-fraction RT. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.