Pathways of metastatic bone spread

Question 1

Where do most adult skeletal cancers metastasise from?

Answer 1

Lung, breast, prostate

Some from kidney and thyroid

Question 2

What type of prostate cancer usually metastasises to bone, and what is the main microscopic finding?

Answer 2

Metastatic prostatic adenocarcinoma

Forms malignant glands

Question 3

What are the 3 most common childhood cancers that metastasise to skeletal areas in children?

Answer 3

Wilms tumour

Neuroblastoma

Rhabdomyosarcoma

Question 4

In the process of metastasis, what is meant by direct extension/invasion?

Answer 4

Primary tumour grows into tissues or structures around it

Question 5

In the process of metastasis, what is meant by lymphatic dissemination?

Answer 5

Primary tumour travels in lymphatic vessels to distant sites

Question 6

In the process of metastasis, what is meant by haematogenous dissemination?

Answer 6

Primary tumour travels in blood vessels to distant sites

Question 7

In the process of metastasis, what is meant by intraspinal seeding?

Answer 7

Primary tumour travels through Batson plexus of veins, which drains the vertebrae and skull anastomoses with veins draining the thoracic, abdominal, and pelvic organs and breast.

Batson plexus acts as pathway for metastatic cells to the spinal column

Question 8

What generally causes lytic lesions to form in bone, due to tumours?

Answer 8

Tumours secrete substances that upregulate RANKL on osteoblasts and stromal cells, which binds to RANK and stimulates osteoclastic activity

eg. PTH-like peptide, prostaglandins, cytokines

Question 9

What generally causes blastic/sclerotic lesions to form in bone, in tumours?

Answer 9

Matrix-bound growth factors are released, which stimulate osteoblastic activity

eg. TGF beta, insulin-like growth factor 1, fibroblast growth factor, WNT proteins