Purpose: To determine the predictive value of the mean platelet volume (MPV) and the MPV/platelet count ratio on the development of isolated bone metastasis in patients with breast cancer.

Methods: A total of 121 previously untreated female patients with isolated bone metastases from breast cancer (group 1) were included in this retrospective cohort study. The patients enrolled in this study had similar age, biological subtypes, and duration of follow-up after diagnosis. Group 1 was compared with both 71 previously untreated women with breast cancer with no metastases at all (group 2) and 39 healthy women (group 3). Demographic data, laboratory tests and histological features of all of the patients in groups 1 and 2 were recorded and the study variables from each of the three groups were compared.

Results: In group 1, the cut-off value (9.2 fL) for the MPV was determined and patients were stratified into 4 subgroups. The MPV was higher in group 1 than in either group 2 or group 3. Group 1 patients had a MPV of 8.8±3.1 fL (mean 5.1, range: 6.1-15.6) and the cut-off value for MPV was 9.2 fl. For patients in group 1, the MPV distribution was stratified into 4 groups as follows: group A included MPV values< 6.08 fL, in group B values ranged from 6.09 to 8.46 fL, group C included values from 8.47 to 10.05 fL, and group D included patients with MPV values> 10.06 fL. MPV and the presence of lymphovascular invasion were found to be independent risk factors for the development of isolated bone metastases. Conclusion: We concluded that MPV can be used to predict the development of isolated bone metastases.