Musculoskeletal Oncology

What are Musculoskeletal Tumors?

Musculoskeletal tumours are masses or lumps of tissue that develop in or spread to the musculoskeletal system as a result of abnormal and uncontrollable cell division. The musculoskeletal system includes the bones, joints, ligaments, muscles, and nerves.

Musculoskeletal tumours are generally classified into two groups: muscle tumours and bone tumours, and they may be considered benign if they are painful but do not spread to other parts of the body, or malignant or cancerous if the cancer cells invade and kill nearby tissue and spread to other parts of the body. If they are malignant or cancerous, your physician will determine if it is a primary cancer, where the cancer cells originate within the musculoskeletal system or a secondary cancer, which means the cancer has begun in another area of the body but the cells have spread to the system.

Both benign and malignant tumours could arise from any bony tissue or mesenchymal soft tissue of the extremities, shoulder, girdle, pelvis, or the axial skeleton. Almost all tumours originate from one of the different histologic types of tissue that involve the musculoskeletal system: bone (osteoid-forming tumours), cartilage (chondroid-forming tumours), and muscle and the fibrous connective tissue (soft tissue tumours).

Types of Musculoskeletal Tumors

Some of the common types of musculoskeletal tumors include the following:

• Ewing's sarcoma: This is a rare cancer that either begins in the soft tissues surrounding the bones or directly in the bones of children and young adults. The long bones of the body, such as the arms and legs, and the pelvis are commonly affected. Pain and swelling are the most common symptoms.
• Chondroblastoma: This is a rare benign cartilaginous tumour that characteristically occurs in the epiphysis of a long bone in young patients. Despite being rare, they are one of the most frequently encountered benign epiphyseal tumours in skeletally immature patients.
• Chondrosarcoma: This condition may occur in the pelvis, thigh areas, and shoulders of older adults. It forms in the subchondral tissue, which is the tough connective tissue between your bones. This is the second most common primary cancer involving the bones. 
• Chordoma: This is a rare type of cancerous tumour that can occur anywhere along the spine, from the base of the skull to the tailbone. Chordomas grow slowly, gradually extending into the bone and soft tissue around them. They often recur after treatment, and in about 40 per cent of cases, the cancer metastasizes (spreads) to other areas of the body, such as the lungs.
• Multiple myelomas: This is the most common type of bone cancer. This occurs when cancer cells grow in the bone marrow and cause tumours in several bones. Multiple myelomas typically display the most activity in bone marrow, which includes the marrow in the spine, pelvic bones, ribs, shoulders, and hips. Multiple myelomas usually affect older adults.
• Osteosarcoma: Osteosarcoma, or osteogenic sarcoma, generally affects children and adolescents, but it can also occur in adults. It has a tendency to originate at the tips of the long bones in the arms and legs. Osteosarcoma may also start in the hips, shoulders, or other locations. It affects the hard tissue that provides the outer layer of your bones.
• Giant cell tumour: This is a rare, aggressive non-cancerous tumour that generally occurs in adults between ages 20 and 40 when skeletal bone growth is complete. This usually develops near a joint at the end of the bone. The location of the tumour is often in the knee, but can also involve the bones of the arms and the legs. It can also affect the flat bones, such as the breastbone or pelvis.
• Adamantinoma: This is a rare type of malignant bone tumour affecting less than 1% of individuals and most often develops in the tibia. It mostly occurs in adolescents and people who are in their 20s but can occur at any age. Adamantinoma is slow-growing and often manifests with pain and palpable fullness.
• Soft tissue sarcomas: These are rare type of cancers that begin in the tissues that connect, support, and surround other body structures. This includes muscle, fat, blood vessels, nerves, tendons and the lining of your joints. Surgical removal is the most common treatment, although radiation and chemotherapy may also be recommended. Some of the common soft tissue sarcomas include liposarcoma, leiomyosarcoma, spindle cell sarcoma, and synovial sarcoma.
• Benign soft tissue tumours: These are more common than benign tumours of bone. They can occur at almost any site, including muscles, ligaments, nerves, and blood vessels. These tumours differ widely in appearance and behaviour and some tumours can be quite aggressive. The majority of the tumours in this category are benign tumours of fat called lipomas. Other benign soft tissue tumours include angiolipoma, fibroma, neurofibroma, myxoma, and hemangioma.

Risk Factors for Musculoskeletal Tumors

The causes of most musculoskeletal tumours are unknown, but some factors that increase the risk include:

• Previous radiation therapy
• Genetic factors and some inherited conditions, such as Li-Fraumeni syndrome
• Other bone conditions, such as Paget disease, fibrous dysplasia or multiple enchondromas

Symptoms of Musculoskeletal Tumors

Some of the common symptoms of musculoskeletal tumours include:

• Pain in the bones and joints
• Swelling over the affected area
• Stiffness or tenderness in the bone
• Difficulty with movement
• Loss of sensation in the affected area
• Fractured bone
• Weight loss
• Tiredness
• Fever

What Happens if Musculoskeletal Tumors are Left Untreated?

If a musculoskeletal tumour is allowed to progress without treatment, symptoms get worse and new symptoms develop over time. As a tumour grows, cancer cells multiply and spread to other parts of the body. Cancer cells invade key organs like the intestines, lungs, brain, liver, and kidneys and interfere with bodily functions that are necessary to live, ultimately leading to death.

Diagnosis of Musculoskeletal Tumors

In order to diagnose musculoskeletal tumours, your doctor may order the following diagnostic tests:

• Physical exam and review of medical history
• X-rays
• CT scan
• MRI scan
• Positron emission tomography (PET) scan
• Blood test
• Bone scan, which checks the condition of the bones
• Bone biopsy, which analyzes a small sample of tissue to diagnose cancer

Treatment for Musculoskeletal Tumors

There are 3 approaches to treat musculoskeletal tumours including surgery, radiation therapy, and chemotherapy.

Surgery: This approach aims to remove the tumour and some of the healthy bone tissue that surrounds it. If some of the cancer is left behind, it may continue to grow and eventually spread.

Limb-sparing surgery, also known as limb salvage surgery, means that surgical intervention occurs without having to amputate the limb. The surgeon may take some bone from another part of the body to replace lost bone, or an artificial bone may be fitted. In some cases, however, amputation of a limb may be necessary.

Some of the common surgeries include:

• Radical resection of soft tissue sarcoma in the extremity: This procedure involves removal of the tumour with a cuff of normal tissue which ensures complete removal of the tumor. This requires the removal of an entire muscle group, the lining of the bone and ligaments or tendons. Expertise in limb salvage promotes the best functional results for the patient. Resection is performed in a manner that maximizes both oncologic and functional outcome.
• Internal hemipelvectomy: This is a technically demanding surgical procedure performed for the treatment of pelvic tumours. During this procedure, a section of the pelvis is removed while preserving blood supply and nerve function to the limb.
• En bloc spinal resection: This is a complex surgery designed to remove tumours within the bones of the spine. The objective of an en bloc resection is to accomplish a total resection of the tumour in one piece, reducing the risk of tumour spread during removal. Multiple vertebrae may be removed. Once the tumor has been removed, spine reconstruction is performed to maintain spine stability and maximize function.
• Expandable endoprosthesis: Removal of bone tumours in children usually results in the removal of one or more of the bone's growth plates. This can lead to a significant shortening of the limb when compared with the unaffected limb that continues to grow normally. Expandable prostheses can be used to non-invasively lengthen the limb. This is achieved by lengthening the prosthesis in small increments over time. The lengthening process is performed during follow up clinic visits and is done without further surgery or anaesthesia.
• Rotationplasty: This is a surgical procedure that can be used to treat malignant bone tumours, such as osteosarcoma or Ewing sarcoma, that occur near a child’s knee. The bottom of the femur, the knee, and the upper tibia are surgically removed. The lower leg is then rotated 180 degrees and then attached to the femur. This unusual procedure preserves the lower leg, attaches it to the thighbone, then uses the ankle as a knee joint.
• Computer navigation: Computer-assisted navigation surgery is specialized surgery utilizing complex 3D imaging in real-time to help the surgeon localize the tumour and the surrounding critical structures. This helps the surgeon navigate complex anatomy often distorted by the tumour. This surgery improves the accuracy, precision, and safety of the procedure and is commonly used in spine, pelvis, and sacral tumour resections.

Radiation Therapy: Radiotherapy is commonly used in the treatment of many cancer types. It involves the use of high-energy X-rays or particles to destroy cancer cells. Radiotherapy works by damaging the DNA inside the tumour cells and preventing them from reproducing.

Radiotherapy can be used to:

• Cure the patient by completely destroying the tumour.
• Relieve pain in more advanced cancers.
• Shrink the tumour, making it easier to then surgically remove it.
• Eliminate the cancer cells that remained behind after surgery.

Combination therapy is radiotherapy combined with another type of therapy. This may be more effective in some cases.

Chemoradiation, or radiotherapy combined with chemotherapy, may also be used.

Chemotherapy: Chemotherapy involves the use of chemicals to treat disease. More specifically, it refers to the destruction of cancer cells. The possible objectives of chemotherapy include:

• Total remission: Chemotherapy aims to cure the patient. In some cases, chemotherapy alone can get rid of the cancer completely.
• Combination therapy: Chemotherapy can help other therapies, such as radiotherapy or surgery, produce better results.
• Delay or prevent recurrence: Chemotherapy, when used to prevent the return of cancer, is most often used after a tumour has been removed surgically.
• Slow down cancer progression: Chemotherapy can slow down the advancement of the cancer.

Chemotherapy may also help to relieve symptoms and is more frequently used in patients with advanced cancer.

Learn more from the American Academy of Orthopaedic Surgeons - Bone Tumor