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 fo r re-treatment of bone metastasis after previous single-fraction radiothera py (RT). Material and Methods: Of 135 patients retreated, 109 patients were retreate d 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 a fter 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 observ ed 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 ch ance to obtain either CR or PR (P = 0.65), while previous PR influenced sub sequent response in the way of achieving more PRs than CRs (P = 0.00054). C ombined, these data showed that patients with initial CR were more likely t o respond than those with previous PR (85% vs. 67%, P = 0.037), There were no difference between the three initial treatment groups regarding the effi ciency (CR or CR + PR) of second RT. Toxicity was low and only gastrointest inal. 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.