Predictive model for survival in patients having repeat radiation treatment for painful bone metastases.

To establish a survival prediction model in the setting of a randomized trial of re-irradiation for painful bone metastases.

Data were randomly divided into training and testing sets with an approximately 3:2 ratio.

Baseline factors of gender, primary cancer site, KPS, worst-pain score and age were included with backward variable selection to derive a model using the training set. A partial score was assigned by dividing the value of each statistically significant regression coefficient by the smallest statistically significant regression coefficient. The survival prediction score (SPS) was obtained by adding together partial scores for the variables that were statistically significant. Three risk groups were modelled.

The training set included 460 patients and the testing set 351 patients. Only KPS and primary cancer site reached the 5%-significance level. Summing up the partial scores assigned to KPS (90-100, 0; 70-80, 1; 50-60, 2) and primary cancer site (breast, 0; prostate, 1. 3; other, 2. 6; lung, 3) totalled the SPS. The 1/3 and 2/3 percentiles of the SPS were 2 and 3. 6. For the testing set, the median survival of the 3 groups was not reached, 11. 3 (95% C. I. 8. 5 - not reached) and 5. 2months (95% C. I. 3. 7-6. 5). The 3, 6 and 12month survival rates for the worst group were 64. 4% (95% C. I. 55. 3-72. 1%), 43. 0% (95% C. I. 34. 0-51. 8%) and 19. 7% (95% C. I. 12. 4-28. 1%) respectively, similar to that in the training set.

This survival prediction model will assist in choosing dose fractionation. We recommend a single 8Gy in the worst group identified.

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2015 Oct 26 [Epub ahead of print]

Edward Chow, Keyue Ding, Wendy R Parulekar, Rebecca K S Wong, Yvette M van der Linden, Daniel Roos, William F Hartsell, Peter Hoskin, Jackson S Y Wu, Abdenour Nabid, Jan Willem Leer, Ernest Vonk, Scott Babington, William F Demas, Carolyn F Wilson, Michael Brundage, Liting Zhu, Ralph M Meyer

Sunnybrook Odette Cancer Centre, University of Toronto, Canada. NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, Canada. , NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, Canada. , Princess Margaret Cancer Centre, Radiation Medicine Program, Ontario Cancer Institute, University of Toronto, Canada. , Leiden University Medical Centre, Leiden and Radiotherapy Institute Friesland, Leeuwarden, Netherlands. , Royal Adelaide Hospital, University of Adelaide, Australia. , Northwestern Medicine Central DuPage Hospital Cancer Center, Warrenville, USA. , Mount Vernon Hospital Cancer Centre, United Kingdom. , Tom Baker Cancer Centre, University of Calgary, Canada. , Centre Hospitalier Universitaire de Sherbrooke, Canada. , University Medical Center St Radboud, Nijmegen, Netherlands. , Radiation Institute Stedendriehoek en Omstreken, Deventer, Netherlands. , Christchurch Hospital, New Zealand. , Akron City Hospital, Northeast Ohio Medical University, USA. , NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, Canada. , Queen's University, Kingston, Canada. , NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, Canada. , Juravinski Hospital and Cancer Centre and McMaster University, Hamilton, Canada.

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