0501 - Palliation of Metastatic Bone Disease

Question 1

What are the five key steps of cancer metastases?

Answer 1

1 - Invasion (through the basement membrane if carcinoma)
2 - Neoangiogenesis via hypoxia and cytokines
3 - Intravasion either passively (shed) or actively (seek out blood vessels)
4 - Survival in bloodstream, thought to be by clumping together
5 - Extravasion - adhesion to vessel wall, invasion through, and new blood supply.

Question 2

Why does cancer metastasize to bone so commonly?

Answer 2

2 theories:
Sluggish flow through marrow allows more time for cancer cells to attach
Marrow may express markers that attract malignant cells in the bloodstream.

Question 3

What are the three ways in which bone metastases can cause hypercalcaemia?

Answer 3

Localised destruction of bone leads to release of calcium
Tumour produces Parathyroid Hormone related Peptide (PTHrP)
Rarely, ectopic production of vitamin D.

Question 4

How does a patient present with bone metastases?

Answer 4

May have hypercalcaemia and possible spinal cord compression.
Severe, worsening pain in the affected area that does not respond well to analgesics.

Question 5

What are the treatment options for bone metastases?

Answer 5

Analgesia
Surgery
Radiotherapy
Chemotherapy
Other Drugs - Bisphosphonates