Correlation between bone scan findings and collagenase activities in patients with breast cancer

RATIONALE AND OBJECTIVES. This study correlates nuclear bone scan findings and measurements of type IV collagenases for the evaluation of bony metastasis in patients with proven breast cancer. METHODS. The authors retrospectively evaluated the final diagnosis of a bone scan and the results of an immunohistochemical staining for 92 kDa and 72 kDa type IV collagenases in, respectively, 30 and 30 patients with metastatic breast cancer, and, respectively, 27 and 26 patients with primary breast cancer. The immunohistochemical staining was performed with tissue specimens obtained from a primary or metastatic breast tumor lesion. The amounts of the enzyme were graded from 0 to 4 and scored by multiplication with the percentage of tumor cells. The confidence of bone scan interpretation also was scored from 1 to 5 with increasing probability. RESULTS. There was a significant difference in enzyme scores between patients with and without metastases. Patients with <170 92 kDa (26 of 27), 72 kDa (26 of 26) type IV collagenase, showed no active bony, lung, or liver metastases. However, there were variable bone scan findings in patients with a >200 enzyme score. CONCLUSION. Bone scan provides no additional benefit in breast cancer patients with a type IV collagenase score of < 170. A bone scan is necessary to confirm, localize, or follow-up bony metastases in patients with an enzyme score of >200.