Demographic, clinical and treatment related predictors for event-free probability following low-dose radiotherapy for painful heel spurs - a retrospective multicenter study of 502 patients

A total of 502 patients treated between 1990 and 2002 with low-dose radiotherapy (RT) for painful heel spurs were analysed for prognostic factors for long-term treatment success. The median follow-up was 26 months, ranging from 1 to 103 months. Events were defined as (1) slightly improved or unchanged pain after therapy, or (2) recurrent pain sensations during the follow-up period. Overall 8-year event-free probability was 60.9%. Event-free probabilities of patients with one/two series (414/88) were 69.7%/32.2% (p<0.001); >58/ < or = 58 years (236/266), 81.3%/47.9% (p=0.001); high voltage/orthovoltage (341/161), 67.9%/60.6% (p=0.019); pain anamnesis < or = 6 months/ >6 months (308/194), 76.3%/43.9% (p=0.001); single dose 0.5/1.0 Gy (100/401), 86.2%/55.1% (p=0.009); without/with prior treatment (121/381), 83.1%/54.9% (p=0.023); men/women (165/337), 61.2%/61.5% (p=0.059). The multivariate Cox regression analysis with inclusion of the number of treatment series, age, photon energy, pain history, single-dose and prior treatments revealed patients with only one treatment series (p<0.001), an age >58 years (p=0.011) and therapy with high voltage photons (p=0.050) to be significant prognostic factors for pain relief. Overall low-dose RT is a very effective treatment in painful heel spurs.