metastasis to the bone is a common complication of breast , lung , prostate , gastrointestinal , haematological , melanoma , and other tumours , , . in many patients with primary breast , prostate and lung primary tumours , bone metastases ( bom ) are signs associated with the presence of disseminated disease . these metastases to the bone will usually result in patients experiencing pain which is often palliated using single fraction radiotherapy ( sfrt ) or multiple fraction radiotherapy ( mfrt ) depending on the factors such as cancer type and presence of complication within the bone , , , . although the distribution of bom have been observed in many skeletal locations , bom that are distal to the elbow and knee joints are considered rare and therefore are infrequently reported . depending on the primary tumour histopathology , the frequency of skeletal bone metastases ranges from 10% to close to 90% and bone lesions are found more commonly within the axial skeletal versus the appendicular skeleton . although any skeletal bone may be involved with metastatic disease , the vertebral body is most commonly associated with metastatic disease ; long bone involvement or metastases distal to the elbow and knee are rare , , . this study sought to assess the incidence of distal bone metastases treated with radiotherapy in a provincial programme . all courses of rt for bone metastases from 2007 to 2011 for patients living in bc were identified in a provincial rt programme . the bc cancer agency ( bcca ) information system ( cais ) was used to identify 8008 patients who received 16,277 palliative radiotherapy courses for bone metastases from 2007 to 2011 . information retrospectively collected on these patients included : patient age , gender , primary tumour histology , fractionation schedules , and location of bone metastases . treated bom were categorized as distal if the bom was located within or distal to the elbow or knee . patients were grouped by primary tumour site as breast , lung , prostate gastrointestinal , haematological , melanoma , and other . multivariable linear regression analysis was used to determine associations between primary tumour type and incidence of distal bone metastases . p values were two - sided , and values less than.05 were considered statistically significant . we used the spss statistical software package , version 19.0 ( chicago , il ) , for data entry and statistical analysis . from 2007 to 2011 , 8008 patients in bc were treated with 16 , 277 palliative radiotherapy courses ; 425 ( 3% ) of the courses prescribed were used to treat bones located within or distal to the elbow or knee . male patients were treated more often than female patients ( 52% ) and sfrt was prescribed 49% of the time ( table 1 ) . breast and lung malignancies were observed most commonly ( 23% ) , followed by prostate ( 19% ) , other ( 15% ) , lymphoma ( 11% ) , gastrointestinal ( 8% ) and melanoma ( 1% ) ( table 1 ) . we demonstrated that melanoma malignancies resulted in the highest frequency ( 5% ) of distal bom ; followed by haematological ( 3% ) , lung ( 2% ) prostate ( 2% ) , other ( 2% ) , gastrointestinal ( 1% ) , and breast ( 1% ) . distal bom where more commonly identified in the lower extremity ( 87% , p<0.001 ) . distal bom were treated with sfrt significantly more often than non - distal bom ( p<0.001 ) ( fig . 1 ) . table 2 presents the multi - variable analysis performed to determine the associations between distal bom and patient characteristics , which demonstrated that patients with melanoma have a significant higher odds of having distal bone metastases ( p=0.004 ) . the regression analysis also showed significant correlation between having distal bone metastases treated at abbotsford centre ( odds ratio 2.37 , 95% confidence interval 1.543.64 , p<0.0001 ) ( table 2 ) . this is the first large scale study to illustrate the incidence of distal bone metastases in patients being treated with palliative radiotherapy ( rt ) . from 2007 to 2011 , 16,277 courses of palliative rt was used to treat bone metastases in 8008 patients ; 425 ( 3% ) of which were rt courses for distal bom . in addition , distal bone metastases were significantly more likely to be treated with sfrt . this population - based study demonstrates that patients with melanoma have the highest proportion of distal bom . this differs from previous reports , which only present that prostate , breast , and lung cancer have the highest absolute number of distal bom , likely because these are the most common cancers with any type of bom , , , , . here we showed that sfrt was used to treat distal bom more often than non - distal bom ( 66% versus 49% , respectively ) , likely because distal bom are located in regions that do not contain organs at risk such as the spinal cord . a weakness of this study is that untreated bom are not captured , and therefore the incidence of distal bom may be under - represented . however , it is unlikely that the proportion of distal bom is markedly different than reported . in addition , the large population - based nature of this study provides adequate power to identify correlations between distal bom and primary tumour type , while being relatively free of selection bias . this population based study identified an incidence of distal bom of 3% among patients treated with palliative rt . mb conceived of the study , participated in the data collection and statistical analysis , and designed and draughted the manuscript . xxx participated in the acquisition of data , analysis and interpretation of data and helped draughted the manuscript .