Osteosarcoma

Incidence

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 to 14 year age group. Incidence is similar in girls and boys up to age 14 years but a male excess emerges at around 15 to 16 years. This male excess arises earlier in Ewing sarcoma of bone (at 10 to 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.

Survival

The survival rate for childhood osteosarcoma has increased in recent years to 65 per cent, thanks to recent innovations in treatment, including the use of multi-agent chemotherapy.

However, this bone cancer has amongst the lowest survival rates of all the childhood cancers, possibly due in part to late diagnosis.

The prognosis varies according to the grade, stage and response to treatment. If the tumour has spread (metastasised) to other parts of the body at the time of diagnosis, survival is drastically reduced. The estimated survival rate for patients with localised osteosarcoma is about 75 per cent compared to 30 per cent for patients with metastatic disease.

The following symptoms may be noted:

• 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.

The doctor may arrange an initial X-ray, and then refer to a cancer specialist who will usually perform a biopsy under anaesthetic (a sample of the affected bone is taken for examination under the microscope), blood tests, and scans (bone scan, CT or MRI).

These tests enable doctors to define the grade and the staging of the tumour.

Osteosarcomas can be defined as high or low grade depending on the appearance of the abnormal cells under the microscope. In high grade tumours the cells are likely to grow quickly and are more likely to spread.

The tumour is staged (1A, 1B, 2A, 2B or 3) according to its size and whether it has spread from the starting site. This system of staging will determine the treatment required.

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Great advances have been made in the treatment of osteosarcoma during the past few decades. In the 1960s the only available treatment was amputation. Only a small number of patients survived more than two years after diagnosis.

It has now been shown that giving chemotherapy before and after surgery improves the outlook for osteosarcoma patients. It also allows some people to have limb-sparing surgery rather than amputation.

Treatment varies according to the size, grading and position of the tumour. It usually involves surgery, chemotherapy and/or radiotherapy.

1. Surgery generally forms the mainstay of treatment for osteosarcoma but the extent of surgery will again depend on the site and size of the tumour. In some cases, the affected limb may need to be amputated, in which case an artificial limb will be developed by a specialist centre. Limb-sparing surgery (involving a prosthesis or bone graft) is possible in many cases.
2. Chemotherapy may be used before surgery to kill the cancer cells and shrink the tumour. It may also continue after surgery to prevent recurrence (relapse).
   A new type of chemotherapy – a biological therapy called mifamurtide – has been introduced in recent years for the treatment of non-metastasised osteosarcoma following surgery. This is given alongside conventional chemotherapy and has improved survival.
3. Radiotherapy is sometimes used in combination with the other forms of treatment.

 Commonly used terms in treatment

Side effects and complications

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.

Follow-up

The child will have regular follow-ups to check for any recurrence of the cancer and for any problems that may arise as a result of the treatment they were given (late effects).

They will be checked up on every few months for the first three years after treatment and then every six months for another two years.

If relapse occurs, it is usually within 18 months of treatment. It may be possibly to successfully treat relapsed disease.

Research

Many children have their treatment as part of a clinical trial.

Trials aim to improve our understanding of the best way to treat the cancer, usually by comparing the standard treatment with a new or modified version.

If appropriate, the child’s medical team will discuss participation in a relevant trial. Participation is optional but may offer the opportunity to receive new treatments.

Children with Cancer UK is funding a number of research projects focused on bone tumours.

Further information

More detailed information about osteosarcoma in children and its treatment is available from Macmillan Cancer Support