Koizumi et al. BMC Cancer 2010, 10:423 http://www.biomedcentral.com/1471-2407/10/423 detection and overall survival and quality of life [3-5]. There have been no studies addressing this topic since then. However, the diagnosis and therapy of skeletal metastasis in breast cancer have advanced considerably since the two RCTs were conducted, and SRE was not used as an endpoint in those trials. Therefore, the results of the RCTs and the present study cannot be compared. Carrying out a RCT with SRE as an end- point could be worthwhile. Research into a new method of detecting skeletal metastasis using bone metabolic markers is underway [20]. Although the sensitivity of bone metabolic markers in detecting skeletal metastasis is currently insufficient, research into new markers is ongoing [20-22]. Another new technique used to detect metastasis, including ske- letal metastasis, is positron emission tomography (PET). A number of publications conclude that PET is a good method for the detection of metastasis [23-25]. It is likely that bone surveys will be undertaken using meth- ods other than bone scans, and that the clinical impact of bone metastasis will be clarified. Conclusions Breast cancer patients who were diagnosed with skeletal metastasis without pain had fewer SREs than those with pain, and pain was a predictor of SRE. Other factors were predictors for CSD. Detection of skeletal metastasis in patients who do not have bone pain leads to a lower incidence of SREs. However, the data did not support a recommendation for bone surveys in the follow-up of breast cancer patients. These results could lead to a new randomized clinical trial to investigate whether early detection of skeletal metastasis has clinical significance. Additional material Additional file 1: Patient demographics and tumor characteristics. Additional file 1 shows patients demographics and tumor characteristics. Additional file 2: Skeletal related events and pain. Additional file 2 shows skeletal related events with and without pain. Additional file 3: Cox propotional hazard analysis as predicotors of SRE. Additional file 3 shows the results of Cox propotional hazard analysis as predicotors of SRE. Additional file 4: Cox propotional hazard analysis as predicotors of CSD. Additional file 4 shows the results of Cox propotional hazard analysis as predicotors of CSD. Additional file 5: Revised skeletal related events* and pain. Additional file 5 shows revised skeletal related events and pain. Revised skeletal related events (SREs) were the events where the first RT was not counted as events. RT at least 3 months apart from the first RT was regarded as revised SRE. Additional file 6: Cox propotional hazard analysis as predicotors of revised SRE. Additional file 6 shows the results of Cox proportional hazard analysis as predictors of revised SRE. Revised skeletal related events (SRE) were the events where the first RT was not counted as events. RT at least 3 months apart from the first RT was regarded as revised SRE. Page 8 of 9 Acknowledgements The authors thank all the members of the Departments of Nuclear Medicine and Breast Surgery at Cancer Institute Hospital, Tokyo, Japan. Author details 1Molecular Imaging Center, National Institutes of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba, 263-8555 Japan. 2Department of Nuclear Medicine, Cancer Institute Hospital, Tokyo 170-8455, Japan. 3Department of Breast Surgery, Cancer Institute Hospital, Tokyo 170-8455, Japan. 4Department of Internal Medicine, Cancer Institute Hospital, Tokyo 170-8455, Japan. 5Breast Center, IUHW Mita Hospital, Tokyo, 108-8329, Japan. 6Breast Center, Juntendo University, Tokyo 113-8431, Japan. Authors’ contributions MK carried out planning of the study, data collection, analysis and interpretation, and writing the manuscript. 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