Tumors that metastasize to bone (mnemonic)

A mnemonic useful to remember the most common tumoursTumours that metastasize to bone. The  may be remembered using the mnemonic "Lead Kettle", spelled PBKTL (lead is PB in Pb on the Periodic Table).

• PB-KTL

Mnemonic

• P: Prostate
• B: Breast
• K: Kidney
• T: Thyroid
• L: Lung

For females, breasts and lungsbreast and lung are the most common primary sites; nearnearly 80% of cancers that spreads tospread to the bonesskeleton are from these locations. In males, prostate and lung cancers make up 80% of the carcinomas metastasizing to bone. The other 20% of primary disease sites in both sexes are: kidney, thyroid, bowelsGI and other placeslocations.

Lytic vs Blastic in the "Lead Kettle" PB-KTL mnemonic:

By knowing the typical behavior of the metastatic lesion -lytic- lytic or blastic- on the bone tissue you can rule out some types andhelp sort between the types to make the mnemonic even more useful.

• Prostate = blastic/sclerotic (induces bone growth)
• Breast = mixed pattern
• Kidney, thyroid, lung = lytic (induces bone destruction)

The spreading pathways of metastasis from the starting site to the bones are only partially understood, and some authors propose some bone metastasis via the Batson Venous Plexus, a two-way, valveless venous pathway that allows cancer cells, infection and emboli to travel freely both to cranial and caudal direction without passing through the main "tumour-catching" places: liver, lung, peritoneum and others.

Carcinoma metastases are the most common malignant tumors in the skeleton, with maybe somewhat vague symptoms or an acute onset, often with pain or pathological fractures. In people with breast and prostate cancer, the bone is often the first distant site of cancer spread. More than 2 out of 3 breast and prostate cancers that spread to other parts of the body spread to the bones.Of lung, thyroid, and kidney cancers that spread to other parts of the body, about 1 out of 3 will spread to the bones. 

Basic knowledge of a simple mnemonic about the main types of bone metastases can be a handy tip in the medical routine: with a good history taking from the patient, clinical findings and sharp eyes on the images it's possible to nail a nice and elegant diagnostic hypothesis allowing a more specific investigation.

Related articles

• Sclerotic bone metastases
• Lytic bone metastases
• Mixed lytic and sclerotic bone metastases
• Skeletal metastases