Dr Frankie Swords
St Bartholomew's Hospital, London

Stereotactic radiosurgery was pioneered in Sweden from as early as 1949. It is a highly precise, high dose Radiotherapy that is given in one session. In those early days there was not an accurate way to see the targeted tumour, so it was not considered suitable for treating pituitary tumours. More conventional neurosurgical results improved, and remained a conventional treatment for pituitary tumours.

It was not used until recent advances in pituitary imaging and radiotherapy planning software (CT and MRI scans) led to a renewed interest in this treatment for pituitary adenomas (or tumours).

The largest experience of radiosurgery is in Sweden, which has had an operational Gamma Knife unit since 1968. In the UK, the first gamma unit opened in Sheffield in 1985 and has extensive experience and impressive results in the treatment of cerebrovascular malformations and intracranial tumours. The Donner Radiation Unit at the University of California went on to develop an alternative method of delivery using heavy charged particle therapy, again requiring specialist dedicated equipment. However, over the last 18 years linear accelerators (Linacs) have been adapted for delivery of radiosurgery, allowing the same machines (which are currently used in virtually every radiotherapy department in the country) to deliver conventional fractionated radiotherapy and single visit radiosurgery routinely with the right software. The first such Linac based radiosurgery unit opened in the UK in 1989 at St Bartholomew's Hospital, and since then at least 5 other NHS facilities and 1 private clinic have opened. In this time, over 400 patients, including 22 with pituitary tumours, have received therapy at St Bartholomew's with excellent results. Furthermore, a new Gamma Knife unit has recently been purchased and so it is now possible to calculate which mode of delivery offers the best chance of results with the lowest chance of adverse effects for each individual patient.

Enthusiasm for this new technology has been high, however the published literature gives mixed results. Some groups, notably in Sweden, have reported the use of radiosurgery as a primary treatment, that is as an alternative to surgery. In one series 28% of patients with Acromegaly were 'successfully treated' compared to a cure rate of over 40% for standard transphenoidal surgery alone. Other groups have used radiosurgery as an alternative to conventional radiotherapy in patients not cured by surgery. However, although many groups describe a more rapid fall in hormone levels after radiosurgery compared to conventional radiotherapy, this is not always the case. At St Bartholomew's, radiosurgery has been used as a third wave of treatment, for 22 patients with continuing pituitary disease, despite prior surgery and conventional radiotherapy. 13 patients with acromegaly have so far received treatment; 100% of these patients had a reduction in Growth hormone levels, and 50% have been cured of disease. No side-effects have yet been reported. So far then, radiosurgery looks like a promising treatment in resistant cases of Pituitary tumour, and as experience in the field grows, so its indications will almost certainly widen. However, until more convincing data on its efficacy and more importantly its side-effects are published, its usefulness compared to the tried and tested treatments of surgery and conventional radiotherapy, will be limited.