[The f-factor (fat infiltration) in breast cancer as a new indicator for predicting the occurrence of bone metastasis].

The correlation between tumor infiltration into extramammary fatty tissues (f-factor) and bone metastasis was retrospectively analyzed in 117 patients with breast cancer. Five (10.6%) and 26 (37.1%) patients developed bone metastases among 47 f-negative and 70 f-positive subjects, respectively, and the frequency of bone metastasis was significantly higher in the f-positive than in the f-negative group (p less than 0.005). Furthermore, bone metastasis was more frequent in the f-positive than in the f-negative group among patients of the same stages, lymph node involvements, or histological types. The f-factor was suggested to be a new indicator for predicting the occurrence of bone metastasis in breast cancer.