Although the risks are low, radiotherapy and chemotherapy can produce mutations, changes in cells that can cause them to behave abnormally.
Because of the wrong diagnoses revealed in the interim report on the Birmingham bone cancer service, at least seven patients were given wrong treatment. According to Dr Bernard Crump, director of public health, South Birmingham Health Authority, three received unnecessary radiotherapy; two unnecessary chemotherapy; one unnecessary chemotherapy and surgery; and one unnecessary surgery and radiotherapy.
In some cases cytology - the examination of cells aspirated through a needle - was used, according to the leaked evidence in the surgeons' report to the interim inquiry team. According to the inquiry, this method is not adequate on its own to be sure the diagnosis is correct.
Chemotherapy is a term for drug treatment associated with very powerful and often poisonous cancer drugs. For bone cancer it is usually given before surgery to shrink the tumour and to make it less likely to spread. Radiotherapy is usually given after surgery, if it has not been possible to remove the tumour completely. Chemotherapy may also be needed.
Both have side-effects that will be experienced equally by those who have cancer and those who do not.
With chemotherapy, these may include unpleasant side-effects including hair loss, nausea, vomiting, sore mouths and low white-cell counts in blood, making the patients vulnerable to infections. Although they improve when the treatment stops, the drugs may be needed for up to a year.
Radiotherapy too has some side-effects, such as hardening of muscle tissue, but technology has rendered them less unpleasant. The risk of a patient getting another tumour, perhaps 12 to 20 years later, is increased by both types of treatment.