Malignancy in a child: Osteosarcoma

Question 1

Define osteosarcoma.

Answer 1

Osteosarcoma is the most common histological form of primary bone cancer. It is most prevalent in teenagers and young adults.

Question 2

Explain the aetiology/risk factors of osteosarcoma.

Answer 2

Osteosarcomas tend to occur at the sites of bone growth, presumably because proliferation makes osteoblastic cells in this region prone to acquire mutations that could lead to transformation of cells (the RB gene and p53 gene are commonly involved)

Question 3

Summarise the epidemiology of osteosarcoma.

Answer 3

Osteosarcoma accounts for just over half of childhood bone tumours, with approximately 30 new cases each year in the UK. Although osteosarcoma can develop in any bone, it occurs most often in the bones on either side of the knee (tibia or femur) and in the upper arm. Osteosarcoma is extremely rare under the age of three years and gradually increases with age, with two thirds of childhood cases occurring in the 10-14 year age group. Incidence is similar in girls and boys up to age 14 years but a male excess emerges at around 15-16 years. This male excess arises earlier in Ewing sarcoma of bone (at 10-14 years). In addition to these childhood cases, a further 45 teenagers and young adults (15 to 24 years) are diagnosed with osteosarcoma every year in the UK.

Question 4

What are the signs and symptoms of osteosarcoma?

Answer 4

• Bone pain – this may come and go initially but then become more persistent
• Tenderness
• Redness
• Swelling
• Fracture may occur after a minor injury at the site of the weakened bone.

Many patients first complain of pain that may be worse at night, may be intermittent and of varying intensity and may have been occurring for some time. Teenagers who are active in sports often complain of pain in the lower femur, or immediately below the knee. If the tumor is large, it can present as overt localised swelling. Sometimes a sudden fracture is the first symptom, because affected bone is not as strong as normal bone and may fracture abnormally with minor trauma. In cases of more deep-seated tumors that are not as close to the skin, such as those originating in the pelvis, localised swelling may not be apparent.

Question 5

What are appropriate investigations for osteosarcoma?

Answer 5

Bloods

Imaging (Xray – CT – MRI – bones scan – PET)

• A characteristic often seen in an X-ray is Codman’s triangle, which is basically a subperiosteal lesion formed when the periosteum is raised due to the tumor. Films are suggestive, but bone biopsy is the only definitive method to determine whether a tumor is malignant or benign.
• Most times, the early signs of osteosarcoma are caught on X-rays taken during routine dental check-ups. Osteosarcoma frequently develops in the mandible (lower jaw); accordingly, Dentist are trained to look for signs that may suggest osteosarcoma.

Bone biopsy

Question 6

What is the management for osteosarcoma?

Answer 6

A complete radical, surgical, en bloc resection of the cancer, is the treatment of choice in osteosarcoma. Although about 90% of patients are able to have limb-salvage surgery, complications, particularly infection, prosthetic loosening and non-union, or local tumor recurrence may cause the need for further surgery or amputation.

Chemotherapy

Radiotherapy

Question 7

What are complications associated osteosarcoma?

Answer 7

In the short-term, treatment can cause side effects such as pain, tiredness, nausea, vomiting, infections, hair loss, bruising, and tiredness. In the longer-term, the child may be at risk of a variety of late effects of treatment. These can occur months or years after treatment finishes and can include abnormal bone growth, heart or lung effects, infertility and an increased risk of developing another cancer. There may be psychological problems associated with having a false limb, as well as the obvious physical limitations.

Question 8

What is the prognosis of osteosarcoma?

Answer 8

5 year survival: 65%