Pituitary Surgery:
Surgery is often required for pituitary adenomas - even those which do not produce excess hormones. Whilst they are usually benign tumours, they can cause problems due to their size and position in the head, ranging from headaches to sight loss if the tumour is putting pressure on the optic nerve. Surgical removal of a pituitary adenoma may successfully remove the entire tumour, or it may "debulk" the adenoma, reducing its mass. Although complete removal is the ideal, it may not always be possible if the pituitary adenoma is large, very hard, or situated close to major blood vessels. Debulking the tumour may also lead to a significant improvement in symptoms, including an improvement in eyesight in cases where it has been affected.
The most common type of surgery for pituitary adenomas is transsphenoidal surgery. This usually takes place through the back of the nose, or through an incision made under the lip and through the gum. Very occassionally, if the tumour is especially large or awkwardly situated, it may be necessary for the surgeon to operate transcranially, where the skull is opened to allow access to the pituitary.
Transsphenoidal surgery on the pituitary is a relatively common operation, but not without its risks. The most common risk is that of damage to the pituitary gland itself, resulting in the patient becoming unable to produce one or more pituitary hormones. Consequently, hormone replacement may be required after the surgery. Diabetes insipidus, a condition with symptoms of excessive thirst and urination, sometimes occurs after surgery due to the pituitary being unable to produce a hormone called vasopressin. It is often temporary and can be treated with medication, but is permanent in 1-2% of patients after pituitary surgery.
Other risks of transsphenoidal pituitary surgery include cerebrospinal fluid (CSF) leak, which is associated with an increased risk of meningitis, and a small risk of blindness as the pituitary is close to the optic nerve. Because the surgery is performed very close to the carotid arteries - major blood vessels supplying blood to the brain - there is also a very small risk of massive bloodloss and death.
After surgery, patients who don't experience complications are likely to be in hospital for 3 - 9 days, and the recovery period is about 4 - 6 weeks, with some people requiring longer. The liklihood that surgery will effect a total cure for the patient varies significantly according to the type and size of tumour.
But after all that doom and gloom, if you're going to have pituitary surgery - perk up! This is about the least-bad operation you can undergo and still tell everyone you've had brain surgery. No-one will ever be able to make you feel bad about being forgetful again.
If you're not the squeamish kind, you can watch a film of transsphenoidal surgery for a pituitary adenoma by clicking here.
Medication:
Whilst there are medical treatments available for certains types of pituitary adenoma which secrete hormones, they vary with regards to their effectiveness and whether or not they are suitable for long-term use. For non-functioning pituitary adenomas, and for other pituitary growths such as craniopharyngioma or Rathke's cleft cyst, there are no medical treatments available; surgery and/or radiotherapy are the options for treatment.
Prolactinoma:
Pituitary adenomas which are over-producing particular hormones may respond to medication which suppresses the body's production of these hormones. Prolactinomas, in particular, are often treated using drugs called dopamine agonists. Drugs such as bromocriptine, cabergoline or quinagolide are often very successful at controlling pituitary tumours which secrete prolactin, returning prolactin levels to normal and often shrinking the size of the tumour as well. However, although some people are able to stop taking these drugs once their hormone levels have normalised, many patients find that their prolactin levels start to rise once they stop taking their medication, and consequently may remain on treatment for life. Because medical treatment is usually effective for prolactinomas, surgery is generally only undertaken on larger tumours or those which have not responded well to medication.
Acromegaly:
Dopamine agonists may also be used to treat pituitary adenomas which produce growth hormone (acromegaly), although they tend to be less effective, and work best in patients whose pituitary tumours produce prolactin as well as growth hormone. Instead, somatostatin analogue injections such as octreotide (Sandostatin) or lanreotide (Somatuline) are the primary medical treatment for acromegaly. They are also an option for long-term treatment in patients who are too high-risk for surgery, although there is an increased risk of developing gallstones when using these medications. Sometimes, dopamine agonists and somatostatin analogues may be used in combination.
Where surgery, radiotherapy and other medications have failed, the third medication option for acromegaly sufferers is pegvisomant (Somavert). Whilst dopamine agonists and somatostatin analogues work by stopping the tumour producing the abnormal amount of hormones, pegvisomant works by preventing the hormones from acting on the body.
TSH-oma:
As with acromegaly, somatostatin analogues lanreotide and octreotide are the main medical treatment for pituitary adenomas which secrete Thyroid-Stimulating Hormone. Dopamine agonists are also sometimes used, but these are only effective in a few cases, particularly in patients whose tumours secrete prolactin as well as thyrotropin.
Cushing's Disease:
Using medication to treat pituitary adenomas that produce adrenocorticotropic hormone (Cushing's Disease) is difficult. Ketoconazole is usually the first medication used to treat Cushing's Disease; it works not by affecting the hormone production of the tumour itself, but by suppressing cortisol production in the adrenal glands. Where it is ineffective, metyrapone may be used in the long-term treatment of Cushing's, either on its own or alongside ketoconazole. Mifepristone has occassionally been used as an initial treatment for severe cases of Cushing's where surgery was not an option, as it inhibits the action of cortisol in the body, but it is difficult to adjust the dosage because mifepristone has an extremely long half-life in the body, leading to a risk of adrenal insufficiency.
Radiotherapy:
Some pituitary tumours may regrow after surgery, and surgery may not be an option for all patients. Pituitary radiotherapy is an option in these cases; it is usually effective at controlling tumour growth for a high proportion of patients.
Unlike surgery, radiotherapy is not immediately effective, but its effects are cumulative and may be felt over a number of years. Because radiotherapy does not immediately stop hormone production in the tumour, patients with secreting tumours will need to continue with medical treatment until the effects of the radiation kick in.
The major side effect from pituitary radiotherapy is that it causes delayed pituitary failure (hypopituitarism), meaning that many patients find that their pituitary ceases to produce certain hormones at some point after radiotherapy, although it may be years down the line. This can be treated with hormone replacement.
There are two possible means of treating pituitary adenomas using radiation: radiotherapy and radiosurgery.
Radiotherapy:
Radiotherapy for a pituitary adenoma is usually undertaken as a series of radiation treatments done once a day, five days a week, for about six weeks depending on circumstances. For patients who live a long way from the hospital where they're having treatment, accomodation may be available at the hospital site. The pituitary tumour will be imaged so that the radiotherapy can be targeted on it accurately. During treatment, patients usually wear a specially created mask to hold their head still while the radiation is delivered.
Radiosurgery:
Unlike radiotherapy, radiosurgery is usually a one-off treatment, in which the pituitary tumour receives a high dose of radiation all at once. The treatment lasts a day, in which the pituitary is first scanned with a CT or MRI machine; the treatment is then planned to focus the beams of radiation very precisely on the tumour, and then the treatment itself may take a couple of hours.
Useful resources:
The Pituitary Foundation have a number of useful resources and informative booklets which you can download from their website.
Cancer Research UK has information on surgery and radiotherapy for pituitary tumours.
Brain Tumour UK have a factsheet on pituitary tumours.
Channel Four did a programme in which they filmed transsphenoidal pituitary surgery live which you can watch here (UK only - but there are other films on YouTube if you search for them)
