TREATMENT OF NON FUNCTIONING ADENOMAS

A. Surgery is the mainstay of treatment and the goals are to restore the visual function, prevent the further worsening of visual and other neurologic deficits and to remove or reduce the tumour bulk. As the presenting symptoms are relatively subtle, majority of these tumours are diagnosed when they have achieved a large or massive size.

Transsphenoidal route is the most appropriate approach for these tumours. A majority of these tumours are soft and can be radically removed. The surgery usually restores the visual acuity and field loss and related symptoms. Less frequently, these tumours are firm and elastic and highly vascular. Even such tumours can be resected by the trans-sphenoidal route. Extent of symptomatic recovery and the recurrence rates depend on the extent of the tumour resection. Radical and total resection of the tumour is usually curative. The long-term outcome after a successful radical tumour resection is excellent.
If a radical surgical excision is achieved, the patient can be clinically and radiologically observed.
Radiotherapy is generally indicated in cases where a significant residual disease is present after surgery (particularly in the cavernous sinus).

B. Radiotherapy
As patients with pituitary adenoma are likely to be long term survivors, high precision techniques such as three dimensional conformal radiotherapy with or without stereotactic guidance (3DCRT/SCRT) should be employed whenever possible, to reduce the late adverse effects of radiation. While IMRT may also be considered, it may not yield any further advantage and carries significant quality assurance.

PLANNING DETAILS

1. Immobilisation: Customised thermoplastic mask/stereotactic frame/mask. Patients undergo a planning CT scan with contrast. A planning MRI scan may also be considered if facilities for CT/MRI fusion are available on the planning system.

2. Volume delineation: Gross tumour volume (GTV) comprises of any visible tumour on the planning scan. A margin of 0.5 cm for possible microscopic extension is added around the GTV to generate Clinical Target Volume (CTV) and edited where no spread is possible (e.g. intact bone). Planning Target Volume (PTV) is generated 3 dimensionally over CTV to account for any errors in daily reproducibility and should ideally be generated in each department individually. In our department, a margin of 0.5 cm and 0.2 cms is given for 3DCRT and SCRT, respectively. Optic chiasm, optic nerves, temporal lobes, brainstem, eyes and lenses should be drawn and doses to these structures should also be preferably calculated, particularly to compare different plans.

3. Field arrangement: In a majority of the patients, one anterior and two lateral or a vertex and two posterior oblique beam arrangement with appropriate wedges and multileaf collimators (MLC), if available provides optimum coverage and conformity. Multiple 6-9 fields may be used for planning SRT/SCRT.
IMRT for pituitary adenomas has not yet become standard of care and should be practiced only at centres with appropriate expertise.

4. Dose: 45 Gy/25#/5 weeks. There is no definite evidence of dose escalation beyond 45 Gy irrespective of tumour size, location and functional status.