Surgical management of primary bone sarcomas

Abstract

This article aims to address the principles of surgical treatment of primary bone sarcomas including chondrosarcoma, osteosarcoma and Ewing’s sarcoma of bone. This piece aims to serve as a guide to experienced orthopaedic surgeons who have limited knowledge of managing musculoskeletal tumours especially primary bone sarcomas. Important principles surrounding surgery involving bone sarcomas, principles of biopsy of such lesions and reconstruction techniques have been discussed. Limb salvage is the expectation in today’s era and though endoprosthesis replacement is an important tool in a surgeon’s armoury, biological methods of reconstruction have also shown to be effective in many settings. Chemotherapy and radiotherapy are vital adjuvant therapies associated with these sarcomas, and they have been discussed in this article.

Introduction

Musculoskeletal tumours especially primary bone sarcomas are uncommon. They account for less than 1% of all diagnosed cancers. In 2010 there were 531 new cases of bone sarcoma in the UK, in contrast to nearly 55,000 new cases of carcinoma of the breast. Surgical treatment of bone sarcomas has changed drastically over the last three decades with increased emphasis on limb salvage. Modern chemotherapy regimens coupled with refined surgical techniques and improved implant designs have drastically changed the way we deal with these sarcomas and today we are in an era of ‘functional limb salvage’ aiming at better quality of life after surgery.

Surgery remains the key to management of bone sarcoma and following proper principles is essential. Numbers of reconstruction options are available after surgery including custom-made and modular endoprosthesis, allograft, vascularized autograft, and recycled autograft via cryotherapy or extra-corporeal radiation and re-implantation of resected bones. Diagnosis and planning of treatment in a multidisciplinary tumour (MDT) board is essential and has benefits of ‘collective wisdom’. Specialists including but not limited to surgeons, radiologists, pathologists, clinical and medical oncologists aim to provide early appropriate care to patients.

Adjuvant therapies (chemotherapy and radiotherapy) are essential in osteosarcoma and Ewing’s sarcoma but less so in chondrosarcoma, where surgery is the mainstay. Timing of surgery is also of utmost importance. In this article we shall discuss the management principles of these malignant bone sarcomas in detail.

Biopsy

When tumour is the rumour, tissue is the issue.

Biopsy of any suspected lesion is important and following principles essential to ensure limb salvage and prognosis is not compromised. Biopsy determines the tumour type and grade. Wherever possible, a biopsy is undertaken under radiological control as exact desired samples are taken for histology analysis. Percutaneous image-guided biopsies ensure that there is no delay in starting any neoadjuvant treatment (which may be delayed with open biopsies as wounds need to heal) and reduce risk of biopsy tract seeding. Open biopsy is indicated when percutaneous biopsy is inconclusive. It would be prudent to get frozen section sample analysis by pathologists when an open biopsy is done to check adequacy of samples available for pathologists to make a diagnosis.

The orientation and location of the biopsy tract are critical, especially as improper biopsy can hamper limb salvage. Biopsy should be planned and performed at the unit undertaking definitive management and should factor in the future skin incisions needed for surgery. If drains are used, they should exit either from the corner of the wound or close in line with the skin incision to make resection simpler in future approaches. Transverse incisions must be avoided.

Careful attention to haemostasis is important to prevent haematoma formation. Biopsy incisions should preferably be made through muscle compartments and neurovascular structures are always avoided ( Table 1 ).

Biopsy what you culture; culture what you biopsy.

Table 1

Principles of biopsy in musculoskeletal tumours

Principle	Rationale
Longitudinal incision in line with future resection and biopsy through a single compartment	Longitudinal incision is extensile Biopsy tract can be excised with final resection remaining extensile
Avoid critical structures, i.e. neurovascular bundles	Contamination of critical structures precludes limb salvage
Biopsy the soft tissue component when present	Bone is weakened when its cortex is disrupted Bone requires decalcification for evaluation and this process may affect pathology
Maintain strict haemostasis Use a drain in line with the incision when needed	Avoid increased contamination outside of the biopsy tract by iatrogenic tumour spread
Advisable to be performed by the surgeon/in the centre where the definitive surgery is planned to be done	Helps in planning for definitive limb salvage surgery
Always culture the biopsy samples	Infection is a common tumour-mimic

Infection is one of the important mimics of tumour. All biopsy samples should be sent for microbiological culture and sensitivity in addition to histology analysis. Antibiotics should not be delivered until the cultures are obtained.

General treatment principles

The primary goal of the treatment of a malignant bone tumour is to remove the lesion with a clear margin to minimize the chances of local recurrence.

Whenever and wherever possible, limb salvage is aimed at. This is possible when the two essential criteria below are met:

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local control of the tumour must be at least equal to that of amputation
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the limb must be functional after salvage.

Surgical margins are graded according to the system of the Musculoskeletal Tumor Society.

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Intralesional margin: the plane of dissection is directly through the tumour. When the surgery involves malignant bone tumours, an intralesional margin results in 100% local recurrence. Intralesional surgeries are performed only in benign tumours, giant cell tumours (GCT) and low-grade cartilage tumors.
•

Marginal margin: a marginal line of resection goes through the reactive zone of the tumour; The reactive zone of any tumour contains inflammatory cells, fibrous tissue, and sparse areas of tumour cells. When malignant tumours are resected through the reactive zone, there is an increased chance of local recurrence (25–50%). A marginal margin may be safe and effective if the response to neoadjuvant chemotherapy has been excellent (95–100% tumour necrosis) but this is only known after definitive resection. Marginal resections are occasionally planned to save critical neurovascular structures.
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Wide margin: this is the preferred margin of resection in primary bone sarcomas. A wide line of surgical resection is accomplished when the entire tumour is removed with a cuff of normal tissue. The local recurrence rate is around 10% when such a surgical margin is achieved. A 2-cm normal margin of tissue is aimed at while planning for resections.
•

Radical margin: this is achieved when the entire tumour and the compartment it involves (surrounding muscles, ligaments, and connective tissues) are removed.

Staging of bone sarcomas is essential prior to surgery and the American Joint Committee on Cancer (AJCC) Staging system is followed routinely ( Table 2 ). Positron emission tomography (PET) scans are used to identify any distant disease but if not routinely available, other modalities of imaging such as full body MRI are employed. Dedicated chest staging should also be undertaken either as part of a PET or a separate CT .

Table 2

American Joint Committee on Cancer staging system for primary malignant tumours of bone for those tumours diagnosed on or after 1 January 2010

Adapted from reference .

Stage	Tumour grade	Tumour size
IA	Low	<8 cm
IB	Low	>8 cm
IIA	High	<8 cm
IIB	High	>8 cm
III	Any tumour grade, skip metastasis ^a
IV	Any tumour grade, any tumour size, distant metastasis

a Skip metastasis: discontinuous tumours in the primary bone site.

Table 3

Comparison of sub-types of osteosarcoma

	Classic (intramedullary)	Periosteal	Parosteal
Age (in years)	<30 and >60	<30	<45
Presentation	Pain and swelling	Pain and swelling	Painless swelling
Histology	Poorly arranged osseous trabecuale with malignant osteoblasts Atypical spindle cells	Osseous trabecuale Chondroblastic elements	Regularly arranged osseous trabeculae Minimally atypical spindle cells
Five-year survival	65%	80%	95%
Management	Chemotherapy and limb salvage surgery	Chemotherapy and limb salvage surgery	Limb salvage surgery