Abstract
Sarcoma is a malignancy of mesenchymal and neuroectodermal tissue, and as such, may arise in any location in the body. It is a rare tumour accounting for less than 1 in 1000 cancers and occurs with an incidence of 1.7–2 per 100000 head of population. Disease free survival following treatment of sarcoma has increased significantly over the last 20–30 years and five year survival for primary bone malignancies is approximately 75–80% and that for soft tissue sarcomas is approximately 70%.
Early attempts at limb sparing surgery was characterised by surgery with narrow margins, complicated incisions and substantial soft tissue bruising. Not surprisingly, the risk of local recurrence was high, but this was attributed to the nature of sarcoma rather than technique, and amputation became the treatment of choice for sarcoma.
In the mid 1970’s, the importance of surgical margins was recognised and guidelines were established for achieving oncologic surgical margins. Intralesional and marginal margins alone were regarded as inadequate, while wide and radical margins were acceptable for achieving local control of disease. The advent of magnetic resonance imaging improved the level of tumour delineation and allowed more accurate preoperative planning. This together with modern chemotherapy and radiotherapy increased the potential for limb sparing surgery.
Reconstruction following tumour resection is an exciting opportunity to protect the function of the limb and the mobility and independence of the patient. There have been a variety of techniques described and these involve either biological, prosthetic or a combination of these options. Reconstructions may be mobile or rigid. Mobile reconstructions frequently utilise prosthetic joints, but at other times pseudarthroses may function similarly, e.g. hip, shoulder. Osteoarticular allografts are also used to maintain joint function following tumour resection. Prosthetic joints incorporate advances in articulation and fixation to improve longevity as many of these devices are implanted into younger patients than normally anticipated for arthroplasty, and these joints are thus, exposed to an increased risk of wear and loosening. Osteoarticular allografts are prone to degenerative changes as well as graft disintegration and infection. Allograft prosthetic composites aim to reduce the articulation problems and may also assist in fixation of the construct. Biologic reconstructions using vascularised or non-vascularised bone are a useful technique for bridging defects and for replenishing bone stock. Adequate soft tissue coverage is vital following reconstruction.
The future of limb sparing surgery will depend on our ability to characterise the biological behaviour of the tumour because this will provide more information on the response of the tumour to treatment, the potential grade of the lesion and thus, its capacity to grown and spread. By understanding the process of tumour progression, we will be able to develop better strategies for treatment. Functional nuclear scanning using isotopes that are metabolised by tumours is a technique that is currently being evaluated as a complementary form of imaging. Chemotherapy has been the cornerstone in the treatment of bone sarcomas, but remains surprisingly disappointing when used for soft tissue sarcomas. Recent meta-analyses have demonstrated only a minimal improvement in disease–free survival with chemotherapy. Novel techniques or agents are required to improve the systemic role of chemotherapy. Patient selection is important and this may relate to their risk of developing systemic spread. Prognostic factors are therefore, important for identifying patients who may be candidates for novel or intensive chemotherapy. Molecular biology is providing an avenue for characterising these tumours but despite the identification of a multitude of distinctive chromosomal abnormalities with their associated gene products, only 2 abnormalities have been shown to be of prognostic significance (19p+ in MFH, and SSX/SYT in synovial sarcoma). Surgeon education is an area where significant advances may be made. Constant reiteration is required to ensure that the principles of proper diagnosis and referral are known. Successful treatment is dependent on knowledge of the criteria for and technique of biopsy, and the principle that the team that will be providing definitive treatment should perform the biopsy. Up to 30% of limbs are sacrificed each year because of inappropriate biopsy or surgery. This figure may be improved upon with greater understanding of the behaviour of sarcomas.
A regimented, multidisciplinary approach to the management of bone and soft tissue sarcomas is likely to improve the local and systemic control of this disease.
The abstracts were prepared by Professor Jegan Krishnan. Correspondence should be addressed to him at the Flinders Medical Centre, Bedford Park 5047, Australia.
