[A retrospective study of bone metastases distribution on 420 whole body scans]

420 patients with cancer of breast, prostate, lung and colon were investigated through 99mTc Methylene-diphosphonate whole body scintigraphy. The presence of pathologic radiotracer uptake was qualitatively and quantitatively analyzed in order to establish the metastases distribution. Patient selection was realized over 2455 whole body scintigraphies effectuated between 1998 and 2001 in our Nuclear Medicine Service. All selected cases were metastases with known origin primary cancer.

Using the Qui-square Test we have compared the frequency of nine well delimited skeleton regions involved like metastatic site in the different cancer types. We have found a significant statistic difference of the range of frequency only between breast and prostate cancers as well as between pulmonary and prostate cancers. The mean number of the metastatic involved skeletal regions was significantly greater in breast and prostate cancers in comparison with lung and colon cancers (p < 0.0001). The higher metastases site frequency was the rachis, than the pelvis, the ribs and the sternum. The skull metastases localization is more frequent in breast cancer in comparison with all other cancers (7.67% versus less than 4% in other cancer types). The pelvis was more involved for the metastatic process in prostate neoplasm. On the other hand, the highest mean anatomic sites number per patient was found in breast cancer (5.7) and prostate cancer (4.8) related to colon (3.3) and lung (3.0) cancers.

Even some particularities were evident, in our study, between the metastases distribution in these four cancer types, the data are not sufficient to sustain the existence of a characteristic pattern related to the primary cancer origin. Metastases localization could be, however, related to the metastazation mechanism.