Musculoskeletal (MS) tumours are primary growths that arise from the bone and soft tissues of the body and limbs in the body.
They can be broadly divided into bone and soft tissue tumours. Each of these tumours can be either non-cancerous or cancerous. The medical term used for malignant MS tumour is "sarcoma ".
Cancer that start from other primary sites such as breast cancer, lung cancers, can spread to bones. These are known as bone secondaries or metastases.
What are the different types of musculoskeletal tumours?
Musculoskeletal tumours are subtyped according to the tissue from which they originate.
Primary malignant MS tumours are relatively uncommon. However, benign ones such as ganglions, sebaceous cysts, exostoses are commonly seen in the population.
There are about 700 to 800 soft tissue sarcomas and 250 bone sarcomas over a 25 year period between 1968 to 1992 in Singapore.
This works out to10 to 15 new cases of bone and 30 to 35 soft tissue sarcomas per year.
Unlike other forms of malignancies, which are common in older adults and elderly people. These sarcomas have a high incidence in childhood, adolescence and young adulthood.
The most common bone tumours seen in clinical practice are bone secondaries.
Malignant MS tumours can present with one or more of the three main features-
A particularly worrisome picture will be that of a mass in the extremity or trunk in a teenager that is persistently painful, even while at rest or at night.
Bone tumours are common around the growing regions of the skeleton, such as shoulders and knees.
Soft tissue tumours can be found in both the body or limbs ; but about 50 % of the soft tissue sarcomas are found in the thigh.
The relative rarity of primary malignant MS tumours may give rise to difficulties in their recognition and in distinguishing them from benign ones.
Most of these cases need careful clinical and radiological evaluation.
Examples of radiological evaluation are : good quality plain radiography ( X-rays ) computer-aided tomography , CAT scans, radionuclide bone scans and magnetic resonance imaging (MRI). These tests may be required in locating these tumours . If there is a suspicion of malignancy, then chest X ray and CAT scan of the chest are essential.
Usually a tissue biopsy would be required to comfirm the diagnosis of MS tumours.
The biopsy may be carried via an open biopsy which requires an operative procedure, or a needle biopsy, which is a minimally invasive procedure.
In either procedure, adequate tissues are sent for examination under a microscope , as well as for culture ( bacteriological analysis).
The results of radiological evaluation and histological examination allows the extent of the tumour to be determined, and the type of tumour, established.
The attending doctor can either choose to treat such cases or refer them to specialised centres with surgical and medical oncologists, if the tumours turned out to be malignant.
Such centres have tumour boards, which consist of multidisciplinary teams of specialists in orthopaedic oncology, medical and radiation oncology with chemotherapy upfront, followed by surgical resections by orthopaedics surgeon, and then chemotherapy again.
Treatment of sarcomas
Sarcomas are presently being treated with a combination of surgical resections, chemotherapy or radiation therapy.
Team approach is important in the treatment of osteosarcomas and Ewing's sarcoma. Such sarcomas are treated by medical oncologist , followed by surgical resections by the Orthopaedic surgeon , and then chemotherapy again.
The aim of any surgical resection is to remove the entire sarcoma without leaving any remnant tumor tissue behind. This is possible if the sarcoma has not already metastasized (i.e. spread) to the surrounding tissues or other organs. ( usually the lungs ).
In cases of sarcomas arising in limbs, careful assessments are needed before recommending surgical options.
If the sarcoma in any limb can be resected with clear margins,with reasonable residual function left in the affected limb, then limb-salvage surgery should be considered.
Treatment of Bone Metastases
In cases of bone metastases, the primary cancer and it's prognosis is taken into consideration if it is known.
If there is already a pathological fracture i.e. the bone has been weakened and broken through metastases, then surgical stablisation and radiotherapy may be required. This is also true of a bone segment or joint that has an impending fracture from metastases.
Options in Limb Salvage Surgery
Bone defects resulting from tumour resections can be filled or bridged with a variety of techniques.
Bone from the patient (autograft) or a cadaveric donor (allograft), metallic endoprosthesis( including joints) or a combination of bone and prostheses can be used to replace most bony defects nowadays.
Soft tissue defects( vessels, nerves, muscles etc) have fewer options in terms of their replacement. Apart from the patient's own limited donor sites, there is a scarcity of available techniques to address the problem.
In the past, the prognosis of sarcomas was dismal. Nowadays, with the multi-disciplinary approach and current surgical techniques, both the prognosis and surgical outcome have brightened considerably.
However, it is still true that large sarcomas in the advanced stages fared worse than smaller ones in earlier stages.
Hence, early detection and treatment are imperative in improving the survival outlook of sarcoma patients.