These occur in 75% of patients with advanced breast and prostate cancer and in 25% of patients with other solid tumours, e.g. lung, GI tract, thyroid, bladder or kidney.

Metastases are either osteolytic or osteoblastic with some patients having both.

Prostate cancer is predominantly osteoblastic while most patients with breast cancer have osteolytic lesions.
In multiple myeloma the lesions are purely osteolytic.

Bone is a frequent site of metastases due to:

• high blood flow
• tumour cell production of adhesins which bind them to marrow stromal cells
• growth factors in bone, including TGFβ, insulin-like growth factor (ILG)-1 and 2, platelet-derived growth factor and fibroblastic growth factors.

Osteolytic metastases

The destruction of bone is mediated by osteoclasts and not the tumour cells. Tumour cells produce parathyroid hormone-related peptide, IL-6, prostaglandin E2, TNF and macrophage colony-stimulating factor (M-CSF) which increase the expression of receptor activity of nuclear factor κB ligand (RANKL) which directly induces formation of osteoclasts and bone resorption. Bone destruction increases calcium levels, which promotes both tumour growth and the production of PTH-related peptide, which is a major factor in osteolytic bone destruction in many tumours. In multiple myeloma there is, additionally, inhibition of osteoblast activity.

Osteoblastic metastases.

The mechanism for this is less clear. It has been suggested that osteoclastic activity precedes osteoblastic activity and bone formation. It is also possible that the vicious circle (as in osteoclastic activity) may be in action, whereby the tumour induces osteoblastic activity and the release of growth factors for osteoblasts, which then increases the growth of tumours. Endothelin 1 has been shown to stimulate bone formation and its levels are increased in, for example, prostate and breast cancers.

2 Comments »

1. [...] in the US. After infection, the virus remains latent in the body for the rest of the person's life.Health Nova: Your Ultimate Medical Portal Bone metastases.Tumour cells produce parathyroid hormone-related peptide, IL-6, prostaglandin E2, TNF and macrophage [...]

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   Comment by Valeyskatrt — July 23, 2010 @ 2:00 am

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