Bone metastases in breast cancer: higher prevalence of osteosclerotic lesions

It is well known that bone metastases from breast cancer usually show osteolytic changes. We retrospectively analysed the computed tomography (CT) appearance of bone metastases to quantify the distribution of lytic, mixed and sclerotic changes in a series of patients presenting with neoplastic bone involvement from breast cancer.

Between 1996 and 2005, 468 women with a diagnosis of breast cancer were referred to our department for staging or follow-up CT examinations. Staging CT examinations detected systemic metastases in 142/468 patients, 60 of which had bone involvement. Patients with a second primary tumour or bone metabolic disorders were excluded from this retrospective analysis.

In patients with bone metastases, CT identified 18 with osteolytic lesions (30%), 32 with osteosclerotic lesions (53.3%) and ten with mixed lesions (16.7%). Analysis of the cases observed for the first time during the 1996-2000 period showed osteolytic lesions in 53.6% (15/28), osteosclerotic lesions in 32.1% (9/28) and mixed lesions in 14.3% (4/28). Results were 9.4% (3/32), 71.9% (23/32) and 18.7% (6/32), respectively, for the same groups in the 2001-2005 period. Histological analysis of all cases included 81.9% of infiltrative ductal carcinoma, 11.2% of infiltrative lobular carcinoma, 3.7% of ductal lobular mixed carcinoma and 3% of medullar carcinoma. We found no statistically significant correlation between histological type of breast cancer and radiological appearance of bone metastasis. A significant difference between patients treated with or without zoledronic acid was observed, with a higher prevalence of osteosclerotic lesions in the former group of patients (p<0.05).

We observed an increasing prevalence of osteosclerotic bone metastasis when comparing the 1996-2000 period with the 2001-2005 period. The significance of these distribution changes is not clear. However, we found a significant correlation of osteosclerotic lesions with zoledronic acid treatment. The advent of third generation bisphosphonates may have changed the CT appearance of bone metastasis from breast cancer.