Metastatic Bone Disease

Don’t forget Multiple Myeloma.

Most common types of metastasis to bone:

• Breast, 50%
• Lung, 10%
• Renal, 10%
• Thyroid 5%
• Prostate 5% (usually osteoblastic- don’t fracture as often. DDx for Paget’s.)

In a child, usually neuroblastoma.

Approximately 10% of patients have a bone lesion as the initial presentation of their cancer. In this situation, it is very important that a careful staging evaluation be performed prior to biopsy. Rougraff and associates have outlined a very simple staging strategy consisting of a chest radiograph, CT scan of the chest and abdomen, serum protein electrophoresis, and technetium bone scan. This simple protocol, along with a good physical examination, will detect the primary site of the tumor in approximately 85% of patients. It is notable that in only about 3% of patients can the primary site of the tumour be identified by reviewing the bone biopsy alone.

Most frequent bony sites for metastasis:

• Vertebra
• Pelvis
• Ribs
• Femora
• Skull

Mets distal to elbow or knee- usually lung or renal primary (have access to arterial system)

Work-up for an aggressive lesion in an older patient: (will detect primary in 85% of cases)

• Focused history and examination
• Chest Xray
• CT chest abdo and pelvis
• Bone Scan
  • May be cold on bone scan: MM, thyroid, renal. They also can bleed alot.
• Serum IEPG, UA

Also need to test:

        Calcium

        EUC (MM causes renal failure)

        LFT, FBC, 

        ESR CRP

        ?Tumour markers eg PSA/Thyroid function

When a metastatic lesion develops in a patient who has a known primary carcinoma and no previous history of mets, biopsy is indicated for re-staging and to determine suitability for chemo or radiotherapy.

Needle or trucut biopsy is generally preferred.

Mirel’s Classification  CORR 1989

Recommend OT if 8 (33% risk of fracture in next 3 months) or more points and >3 month life expectancy.

If 7 points (1 of 41 fractured): radiotherapy and observation.

10 points- all fractured

Treatment options

Radiotherapy 

• excellent for bone pain
• usual dose is same as for HO- 6-8 gray if single dose (600-800cGy) – May occasionally do longer 5-10 day course depending on size or location

Bisphosphonates (good for bone pain - don’t effect tumour growth).

Chemotherapy / Hormone therapy

Radionuclides eg Strontium-89

Surgery

Internal Fixation +/- cement

• Try for IM (intramedullary) fixation if possible with recon options

Arthroplasty

• Esp for any neck of femur fracture- from IT (intertrochanteric) region up
• Always use a long cemented implant (for radiotherapy will effect ingrowth)

Surgical wounds in sites of previous (recent or old) Radiotherapy

If less than 45G total dose - wound should heal

If >60G- wound will probably not heal.