The Role of Surgery in Metastatic Disease to the Bone

Cancer

Incidence (%)

Post-mortem incidence of bone metastases in % [2]

Multiple myeloma

100

Breast

47–85

Prostate

54–85

Thyroid

28–60

Bladder

Renal

33–40

Lung

32–40

Liver

Ovarian

G.I.

3–11

Oesophageal

5–7

Rectal

8–13

Uterine

Very rare

Breast screening has helped to decrease breast cancer mortality with earlier detection and management of the disease. In 2012, there were more than 464,000 new cases of breast cancer in Europe, with a mortality rate of approximately 25%. It is the second most common cause of death from cancer, after lung, in females in the UK [1].

With a 10-year survival of 72%, the cumulative incidence of bone metastases at any time is 8.2% at 2 years and 27.3% at 10 years [3]. Therefore, at 10 years bone metastases in breast cancer potentially pose a substantial problem with over 10,400 cases in the UK per annum.

Skeletal metastases in breast cancer patients can involve any bone, with the femur and spine the commonest. Impending bone fracture is a risk, and therefore an orthopaedic surgeon should be involved early in their management.

50.2 Clinical Presentation/Diagnosis and Investigations

Patients with bone metastases can present clinically in a number of ways:

Acute presentation with a pathological fracture or neurological involvement
Symptoms of metastatic spinal cord compression or cauda equina syndrome
Bone pain
Staging imaging tests revealing evidence of bone involvement or destruction
Acutely with biochemical disturbance, e.g. hypercalcaemia

The orthopaedic surgeon has a number of roles to play in the management of metastatic bone disease, including diagnosis, fixation and prevention of pathological fractures, and occasionally for potentially curative (en bloc) excision of solitary metastatic tumours, although this is still controversial.

The simplest diagnostic tool to assess whether patients are at risk of impending fracture is the Mirels’ scoring system (◘ Table 50.2) [4]. Patients scoring in excess of 8 should be referred urgently for an orthopaedic surgical opinion to consider prophylactic intramedullary nail fixation.

Table 50.2

Mirels’ scoring system

Variable	1	2	3
Site	Upper limb	Lower limb	Peri-trochanter
Pain	Mild	Moderate	Severe
Lesion	Blastic	Mixed	Lytic
Size/bone diameter	<1/3	1/3–2/3	>2/3

From Mirels Ref. [4] with permission from Wolters-Kluwer

Guidelines have been developed over the last decade or so, initially by the British Association of Surgical Oncology (BASO) and subsequently the British Orthopaedic Association (BOA) and the British Orthopaedic Oncology Society (BOOS) [5]. These BOA/BOOS guidelines have been recently updated (► www.boos.org.uk). Further international guidelines have been published by the Japanese Associations of Medical Oncology, Radiation Oncology and Orthopaedics [6].

The new British guidelines have declared four minimum standards of care for the orthopaedic management of patients with metastatic bone disease:

Access to an orthopaedic surgeon as part of multidisciplinary care
Access to an up-to-date oncologist’s opinion with dialogue between the oncologist and the orthopaedic surgeon
Appropriate orthopaedic follow-up whilst the patient remains symptomatic
Data collection on the outcome of skeletal metastases

In the case of many breast cancers, cases are discussed in a multidisciplinary setting; however orthopaedic surgeons are not typically part of these. Options available are to discuss cases outside of the multidisciplinary team as soon as possible or to have a dedicated separate MDT or section of the advanced breast cancer MDT where an orthopaedic surgeon can attend.

50.2.1 Biopsy

Biopsy plays a very important role in the diagnosis of bone metastases. The following points should be noted:

Not every bone metastases needs a biopsy; however, if there is doubt, then biopsy should be the default option.
A new (first) bone lesion requires a biopsy to confirm bone metastases except in the presence of visceral metastatic disease.
A biopsy should be considered if the patient has a known malignancy with pathological fracture, solitary or multiple bone lesions and is mandatory in any pathological fracture in an otherwise healthy patient.
In metastatic breast cancer, it is not uncommon for the cancer phenotype to change, e.g. ER + ve to ER –ve. Biopsy for a change of phenotype has important implications for non-surgical oncological treatment. This is a relatively a new indication for bone biopsy and is likely to increase. Biopsy for phenotypic changes can also be performed on visceral metastases, if present, which may be technically easier than bone biopsy in some cases.
A biopsy can be performed by the orthopaedic surgeon paying special attention to ensuring accurate tissue sampling, haemostasis and preferably via a surgical approach that can be utilised should future surgery need to take place.

Appropriate staging should be performed for the patient along with sufficient radiological investigation (radiographs, CT and/or MRI) of the affected bone following discussion between the orthopaedic surgeon and oncologist. This should ideally be performed prior to bone biopsy and may be necessary to exclude a primary bone tumour.

50.3 Surgical/Orthopaedic Management

The principal role of the orthopaedic surgeon in surgery for skeletal metastases is to provide pain relief to the patient. Further goals, in advanced disease surgery, may be to maintain or restore neurological function and enable functional rehabilitation particularly if the upper limb is involved. This will depend on both the current status of the bone involved in the metastases and the general health of the patient. Pathological fracture following destruction of the bone by metastatic disease may ensue following microfractures causing bone pain. This can lead to an inability to use the limb, affecting stability and weight-bearing status.

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