osteosarcoma

Osteosarcoma

A osteosarcoma (sarcoma Osteogenic) is the most common of primary bone malignant tumours, excluding myeloma and lymphoma. It has a predilection for the metaphyses region of long tubular bones. 50% of cases occur around the knee. It is a malignant (soft) connective tissue tumor whose neoplastic cells exhibit osteoblastic differentiation and form tumor bone. With the advances in oncology medicine, the osteosarcoma has a much better prognosis than a few years ago. This form of cancer is relatively rare.

Frequency
Osteosarcoma is the eighth most common form of childhood cancer, comprising 2.4% of all malignant tumours in pediatric patients, and about 20% of all primaires1 bone cancers.

The incidence of osteosarcoma is estimated at 5 cases per million inhabitants per year for the American population, with a slight variation between black, Hispanic and white ethnic groups (respectively 6.8, 6.5 and 4.6 cases per million people and per year). This is slightly more common among men (5.4 per million per year) than in women (4.0 per million per year) 1.

It most often originates in the metaphyseal region of long tubular bones, with 42% occurring in the femur, 19% in the tibia, and 10% in the humerus. About 8% of the cases occur in the skull and jaw, and 8% in the bassin1.

Prevalence
Osteosarcoma is the sixth most common cancer in children under 15 years of age. It affects 400 children under the age of 20 and 500 adults (mostly between 15 and 30 years) each year in the United States. About 300 of the 900 people die each year. A second peak of frequency occurs in the elderly, most often associated with underlying bone pathology such as Paget's bone disease. There are 150 to 200 new cases per year in France [ref. desired].

Genetic predisposition
Familial cases where the deletion of the ' 13q14 ' chromosome inactivates the retinoblastoma gene is associated with a high risk of osteosarcoma development.
Bone Dysplasias, including Paget disease, fibrous dysplasia, enchondromatosis and multiple exostoses disease, increase the risk of osteosarcoma.
Li-Fraumeni syndrome (TP53 germ line mutation) is a predisposing factor in the development of osteosarcoma.
Rothmund-Thomson syndrome (i.e. autosomal recessive transmission involving congenital bone malformations, hair and skin dysplasia, hypogonadism, cataracts) is associated with an increased risk of disease.
Mortality and survival
Deaths due to malignant bone and joint tumours represent an unknown number of childhood cancer deaths. Mortality rates due to osteosarcoma have decreased by about 1.3% per annum. Long-term survival probabilities for osteosarcoma improved considerably during the late twentieth century and approximated 68% in 20091.

Pathology

Predilections of Osteosarcoma
The tumor can be located at the end of the long bone. Most often, it affects the proximal end of the tibia or humerus, or the distal end of the femur. The osteosarcoma tends to affect the areas around the knee in 60% of cases, in 15% of cases it is around the hip, 10% in the shoulder and 8% in the jaw. The tumor is solid, hard, irregular, (described as "fir" or "Ray of Sunshine" on X-ray examinations) due to the tumor spicules of calcified bone radiating at right angles. These right angles form what is called a Codman triangle. The surrounding tissues are infiltrated.

Under the microscope the characteristic of osteosarcoma is the presence of osteoid (bone formation) in the tumor. The tumor cells are very pleomorphic (anaplastic), some are giant, many atypical mitoses. These cells produce ostéoïdes describing irregular spans (amorphous, eosinophils/roses) with or without central calcification (Hematoxylinophilic/blue, granular)-tumor bone. Tumor cells are included in the Osteoid matrix. Depending on the characteristics of the tumour cells present (whether they resemble bone cells, cartilage cells or fibroblast-like cells), the tumor may be a subclass. Osteosarcomas can present giant osteoclast onto cells as Multinucléées2

Causes

The causes of the osteosarcoma are not known. Several research groups study cancer stem cells and their potential to cause TUMEURS3. Radiation therapy for unrelated conditions can be a rare4 cause.

Symptoms

The symptoms are not obvious to identify. In general, they are in the form of slenderness in the part or in the member reached when the individual is at rest. This pain, strong and well localized, is accentuated by a pressure on the bone. Possible tendonitis (tendinitis at the elbow that does not heal: Case for the osteosarcoma of the humerus). In extreme cases, it is detected during a spontaneous fracture of the bone (in this case the tumor consumed almost all of the bone).

Signs

Persistent pain (despite anti-pains) that become insomniantes.

Treatment

A polychemotherapy (AI API Protocol) is prescribed with the surgical removal of the tumor and a possible prosthesis installation to replace the bone.

Prognosis

Depending on the speed of detection and the grade and metastatic state, the prognosis for healing is greater than 70% if the pathology is taken care of early (great improvement in recent decades) but is bad if not with Many deaths due to metastases (especially pulmonary) within two years.

Canine osteosarcoma

Osteosarcoma is the most common primary bone tumour in dogs and is characterized by particularly aggressive biological behaviour, both locally (in the affected bone) and remotely (metastatic release). Dogs of large and giant breeds are more typically achieved and among the predisposed breeds are: Rottweiler, English Greyhound, Irish Wolfhound, mountain breeds (Grand Pyrenean, Newfoundland, Leonberger), Great Dane (German Mastiff). The most frequent sites of osteosarcoma in the appendicular skeleton are, in order, the distal radius and proximal humerus (thoracic limb), and tibia (distal or proximal) and distal femur (pelvic limb). This is why it is sometimes mentioned that the most traditional locations are "far from the elbow, near the knee". In small breeds, the locations are more often found on the axial skeleton and on the skull.

Osteosarcomas are classified as central or medullary, Périostaux, Parostéaux and skeletal. The most common skeletal locations in the dog are the mammary glands and the spleen. As in humans, the WHO classification of dog and Cat recognizes several histological types: osteoblastic (non-productive, moderately productive, productive), Chondroblastique, Fibroblast, Télangiectasique, giant cell and poorly Differentiated.

The rate of progression of malignant tumours is relatively high. At the time of diagnosis, the prognosis is already reserved and the life expectancy reduced. The metastatic release of Osteosarcomas is indeed often precocious with frequent invasion of the lungs. When no metastases are detected in the diagnosis, the standard treatment of canine osteosarcoma is the amputation of the affected limb, followed by post-operative chemotherapy. The average survival prognosis of an amputee dog but not treated in chemotherapy is about 4-5 months, while it is 9-11 months when the amputation is followed by chemotherapy. The quality of life of amputee dogs is generally excellent. When amputation is not possible, a palliative therapy, aiming to improve the quality of life of the dog, is possible and may include: palliative radiation therapy, anti-inflammatory, other analgesic agents (morphine and others), Aminobisphosphonates (Drugs inhibiting bone remodeling), etc.

The Osteosarcoma appendicular (members) of the cat is more frequently encountered on the pelvic limbs, unlike the dog. Similarly, the prognosis of cats with osteosarcoma appendicular is better than that of a dog, with a median survival exceeding 18 months with surgery alone (amputation).