Management of Bone Metastasis with Radiotherapy

Management of Bone Metastasis with Radiotherapy

Introduction

In solid tumours, bone metastasis most commonly happen in prostate, breast and lung cancers.

In vertebra spine, bone metastasis can cause catastrophic compression fracture (bone fracture that compresses the spinal cord) which leads to:

  • paraplegia (paralysis of both lower legs)
  • quadriplegia (paralysis of both upper and lower limbs if compression fracture happened at higher levels; cervical spine)
  • sciatica/ neuropathic pain (severe current-like pain due to compression of nerve roots)

Bone metastasis in weight bearing limbs (legs) or pelvis, due to the heavy burden, can easily cause severe pain or pathological fracture.

Treatment Plan for Bone Metastasis

Management of bone metastasis is a team effort which includes orthopaedic surgeons, clinical oncologist, physicians, physiotherapist, occupational therapist and patient’s family members/ carer

Any impending fracture/ pathological fracture?

  • Especially in weight bearing area such as femur/ thigh bone, there is high likelihood of impending fracture.
bone mets shoulder.jpg
Bone metastasis to the proximal humerus. It is important to search for lytic lesions or areas of sclerosis. Impending fracture can be treated early with palliative radiotherapy to kill off all cancer cells at the affected area. If axial cortical bone destruction more than 30mm, there is high risk of fracture and prophylactic instrumentation can be suggested to prevent pathological fracture. (MJ Tingart, ‎2003)
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Spinal cord compression due to retropulsion of vertebra bony cortex into spinal canal. Paraplegia (loss of power both lower limbs) and caudal equine (loss of bowel and bladder functions) are possible outcomes.
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Spine instability neoplastic score (SINS Score) helps to assess tumour related instability of the vertebral column. Surgical consultation is recommended when total score is 7 and above. (Fisher, 2010)
  • It’s better to anticipate problem and refer to our orthopaedic surgeon for prophylactic instrumentation and stabilisation.
  • Unfortunately, not all patients will benefit from this procedure, especially those who are already weak and bed bound. We actually referred to orthopaedics a lot but only a few will undergo surgery (another issue is the high cost of implants).
  • In post-op patient, palliative radiotherapy is given to consolidate treatment and to kill off cancer cells from continuously weakening the bone.
  • If not operable, palliative radiotherapy will help to reduce pain, decreasing tumor mass which can relief compression of spinal nerve roots and prevention of fractures (after sterilising/ killing all cancer cells at radiated field).

How is the pain control?

Patient in bone metastasis can happened due to bone fracture(s), cord compression on nerve roots or due to expanding bony metastasis stretching bony cortex.

Pain affects patient’s daily activities, especially sleeping and movements.

Due to pain also, patient is afraid to move about/ ambulate and this will lead to another problem; deep vein thrombosis (DVT)/ blood clots in deep veins in the legs.

Starting patient on opioids derivatives (syrup morphine, oxycodone, oxynorm) and slowly increasing the dose until pain is well controlled.

Patient need to use the pain scoring system (1-3, 4-6, 7-10, mild-moderate-severe pain) to communicate with doctors.

If usage of opioids is very high (need high dosages) or patient unable to tolerate side effects of opioids (nausea, giddiness), palliative radiotherapy can also help to reduce pain caused by bone metastasis.

When pain recur, re-treatment with palliative radiotherapy is still possible.

Screenshot 2018-11-28 at 1.57.49 AM.png
Above showed gradual reduction of pain score after palliative radiotherapy for painful bone metastasis. Unlike opioids which cause immediate pain relieve, the response time for palliative radiotherapy effect (in reducing pain) is more gradual, reaching maximal effect around 1.5 – 2 months time. In the meantime, after palliative radiotherapy, opioids must still be continue and only slowly reduced after 4-6 weeks of palliative radiotherapy. (YM van der Linden, ‎2004)

Any hypercalcemia?

  • High calcium which can leads to lethargy, muscle ache, cramps, nausea, vomiting, constipation, abdominal pain and in severe derangement can cause confusion and disorientation.
  • Monthly treatment with biphosphonate or denosumab will be able to control hypercalcemia easily, plus also strengthening bones and reduce skeletal related events (SREs).

Skeletal related events (SREs): pathologic fracture, spinal cord compression, necessity for radiation to bone (for pain or impending fracture) or surgery to bone.

Strategies to optimise patient’s independence

Physiotherapist and occupational therapist referral to help patients to optimise their independence and to accomplish their daily activity.

In patient with paraplegia (weakness) of the limbs, we will refer for muscle strengthening exercise to regain ambulation/ walking.

For patients with paralysis of the limbs, the focus is on prevention of muscle contracture/ permanent shortening of muscles, which causes stiffness/ frozen joints.

Contracture.jpg
Lower limbs contracture.

Palliative Radiotherapy for Bone Metastasis

Radiotherapy for bone metastasis

  • efficacious (able to reduce painful bone metastasis, prevent fractures, consolidate treatment after surgery and reduce size of cancer mass)
  • non-invasive, convenient
  • quick treatment (around 10 minutes or less each fraction, depending on fraction size)
  • cost-effective
  • minimal to no side effects (occasional flare in pain can be controlled well with opioids or steroids)
  • re-treatment possible

Palliative radiotherapy is normally given in single fraction (8Gy x 1) or short-hypofractionation (20Gy/5#, 30Gy/10#, 40Gy/15#, etc.)

Curative Radiotherapy for Bone Metastasis

In patient with oligo-metastasis to the bone/ vertebra body and long life expectancy, advanced radiotherapy technique (stereotactic body radiotherapy, SBRT or spine stereotactic radiosurgery, SRS) can offer ‘curative’ treatment.

Oligometastases is defined by a state of limited systemic metastatic tumors for which local ablative therapy could be curative.

Another definition is disease stage with a limited number of clinically detectable metastases. (Hellman S, 1995)

By delivering highly focused and ablative dose to solitary bone metastasis at vertebra spine, all cancer cells at the irradiated area will die off and remineralisation of the vertebra will occur.

It’s ‘surgery’ without knife, without cutting anything out and without any need for expensive implants.

Screenshot 2018-11-28 at 1.37.22 PM.png
International guidelines for spinal stereotactic radiosurgery
Screenshot 2018-11-28 at 1.37.39 PM
International Spine Radiosurgery Consortium anatomic classification system for consensus target volumes for spine radiosurgery.
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Example of different radiotherapy treatment planning (Image by P Poortmans)
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Follow up after ablative/ ‘curative’ radiotherapy treatment. Remineralisation can be seen here. (Image by P Poortmans)

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