What is sarcoma?
Sarcomas are malignant tumors that arise from musculoskeletal system tissues such as bone, muscle or connective tissue.
What is the difference between a benign tumor and a malignant tumor?
Malignant tumors ("cancers") are capable of spreading to other parts of the body whereas benign tumors cannot spread. Some benign tumors are called "aggressive" because they can destroy nearby bones and soft-tissues yet do not spread to other body sites.
What is the difference between a carcinoma and a sarcoma?
Most cancers (>90%) arise from "epithelial" tissues, such as the inside lining of the colon, breast, lung or prostate. These are referred to as carcinomas and usually affect older people.
Sarcomas are tumors that arise from "mesenchymal" tissues such as bone, muscle, connective tissue, cartilage and fat. Sarcomas occur in young people as well as in adults and comprise less than 1% of all cancers.
Sarcomas are named by the tissue of origin, for example "osteosarcoma" arises from bone, "liposarcoma" arises from fat and "chondrosarcoma" arises from cartilage.
What is tumor "grade"?
In contrast to carcinomas, sarcomas are graded "low", "intermediate" or "high-grade" by the pathologist. This corresponds to the probability of the tumor spreading to other parts of the body. Typically, only patients with high-grade tumors receive chemotherapy.
How do we make a diagnosis?
In most cases, the patient's history, examination and imaging studies will predict the diagnosis. However, a definitive diagnosis is not made until a biopsy is performed and tissue obtained for pathological examination.
What imaging studies are required?
Most patients with musculoskeletal tumors will undergo more than one type of imaging study. The various imaging studies provide complementary information. Below is a list of the imaging studies we use:
- Plain radiograph (X-ray)
- shows the overall appearance of bone tumors. Experienced Orthopaedic Oncologists and Skeletal Radiologists can predict the diagnosis of a bone tumor with the plain radiograph since most tumors have a "typical" appearance on x-ray.
- Computed tomography (CT)
- is very useful because it reveals the fine details of bone lesions.
- Magnetic Resonance Imaging (MRI)
- reveals details of normal and abnormal soft tissues. It is also good at determining the extent of tumors in inside of bones.
- Bone scan (Bone scintigraphy or Nuclear Medicine)
- is a sensitive test of bone inflammation and can screen the entire skeleton at once. It is usually used to look for evidence of tumor spread to other bones. For the test, the patient is given an intravenous injection of a radiotracer compound. Then, at intervals following the injection, a special camera is used to record uptake of this radiotracer from the skeleton. Since bone inflammation can be due to fracture and infection as well as tumors, bone scan findings must often be confirmed with other tests or a biopsy.
- PET scan (Positron Emission Tomography)
- is analogous to a bone scan in that a radiotracer is injected and that entire body is imaged, however, the level of detail in the image is finer and PET scan is more sensitive for soft tissue lesions than bone scan.
- is an imaging study that shows only the arteries (and veins) in a part of the body. It is usually used in advance of surgery to reveal precise vascular anatomy. It is also very useful in determining the amount of tumor vascularity which usually corresponds to how quickly a tumor is growing.
What is neoadjuvant chemotherapy?
"Neoadjuvant" or "Induction" chemotherapy is chemotherapy is given prior to surgical removal of a tumor. By killing all or part of the tumor, it permits a smaller operation and makes a limb-sparing surgery safer (i.e., prevents tumor recurrence). Chemotherapy is usually continued after surgery. This is essential to kill any remaining tumor cells at the surgical site as well as elsewhere in the body. Most bone sarcomas, such as osteosarcoma and Ewing's sarcomas, are treated with neoadjuvant chemotherapy and limb-sparing resection. With this combination, 95% of our patients have been able to successfully undergo limb-sparing surgery and avoid amputation.
What is radiation therapy?
Radiation therapy is the use of carefully calibrated amounts of high-intensity radiation to kill tumor cells. It is usually used after surgical resection of tumors to kill any remaining cells. It is administered by radiation oncologists and given in brief, daily, outpatient treatments over several weeks.