Pituitary tumours develop in the pituitary gland, which is located behind your eyes. The pituitary gland is connected to the brain via the hypothalamus, and are both considered to be primary endocrine glands (glands responsible for the production and secretion of hormones) of the body.
The pituitary gland is composed of two main portions: the anterior pituitary and posterior pituitary.
The anterior pituitary is the larger, frontal portion of the pituitary gland. This portion of the gland produces and secretes hormones that control other endocrine glands, including growth hormone (also known as GH or somatotropin), thyroid-stimulating hormone (also known as TSH or thyrotropin), adrenocorticotrophic hormone (also known as ACTH or corticotropin), luteinizing hormone (also known as LH or a gonadotropin), follicle-stimulating hormone (also known as FSH or a gonadotropin), and prolactin.
The posterior pituitary is the smaller, back portion of the pituitary gland. This portion of the gland stores and secretes hormones produced by the hypothalamus, including vasopressin (also known as the antidiuretic hormone or ADH) and oxytocin.
Pituitary tumours are more common in women, and tend to develop in people between the ages of 30 and 40. However, this disease can affect anyone.
Types of Pituitary Tumours
Pituitary tumours can be classified by how the cancer cells look under the microscope, as well as whether they are functional (produce hormones) or non-functional (don’t produce hormones).
Pituitary Adenomas
Pituitary adenomas (non-cancerous or benign tumours) are the most common type of pituitary tumour. These types of tumours are slow growing, rarely metastasise and can be asymptomatic. Pituitary adenomas can be functional or non-functional, and are usually found in the anterior pituitary lobe.
Functional Pituitary Adenoma – Prolactinoma
Prolactinomas, or lactotroph adenomas, are the most common type of functional pituitary adenoma. These tumours produce excess prolactin hormone, which is responsible for milk production in females. These tumours often have a good prognosis.
Functional Pituitary Adenoma – Somatotropinomas
Somatotropinomas, or Somatotropin adenomas, are the functional pituitary tumours that produce and secrete excess growth hormone (GH). GH promotes body growth throughout childhood, and can cause giantism or acromegaly if too much is produced in children or in adults. These tumours often have a good prognosis.
Functional Pituitary Adenoma – Corticotropinoma
Corticotropinomas, or corticotroph adenomas, are the functional pituitary tumours that produce and secrete excess adrenocorticotrophic hormone (ACTH). ACTH promotes the growth of the adrenal glands, as well as steroid hormone production. Too much ACTH can cause Cushing’s disease. These tumours can have a good prognosis when caught early.
Functional Pituitary Adenoma – Gonadotropinoma
Gonadotropinomas, or gonadotroph adenomas, are the functional pituitary adenomas that produce luteinising hormone (LH) and follicle-stimulating hormone (FSH). In women, LH and FSH regulate the menstrual cycle and ovulation, and signal for the production of the female hormone’s oestrogen and progesterone. In males, LH and FSH control sperm production and signal for the production of testosterone. Excess levels of these hormones can cause severe fertility issues. These tumours are very rare.
Functional Pituitary Adenoma – Thyrotropinoma
Thyrotropinoma, or thyrotroph adenomas, are functional pituitary tumours that produce and secrete excess thyroid-stimulating hormone (TSH). TSH promotes growth of the thyroid gland, and produces thyroid hormones that regulate the body’s metabolism. Excess TSH could result in hyperthyroidism. These tumours are very rare.
Functional Pituitary Adenoma – Plurihormonal
In rare cases, a pituitary tumour may secrete two or more pituitary hormones. This is called a Plurihormonal adenoma, and may involve a combination of treatments to counteract the effects of multiple hormones in excess.
Non-functional Pituitary Adenomas
Non-functional pituitary adenomas, or null cell adenomas, do not produce or secrete hormones. They are often asymptomatic when small, but as they grow may cause symptoms. These tumours can have a good prognosis.
Plurihormonal Pituitary Adenomas
In rare cases, functional pituitary adenomas can produce more than one hormone. The most common combination is production of growth hormone and prolactin.
Pituitary Carcinomas
Pituitary carcinomas (cancer arising from cells lining tissues and organs) are incredibly rare. In many cases, they are functional tumours and act like functional pituitary adenomas. Pituitary adenomas and carcinomas are indistinguishable under the microscope, and can only be distinguished by whether or not the tumour metastasises. In most cases, pituitary carcinomas metastasise to the brain, spinal cord or bone surrounding the pituitary gland, but can spread to other parts of the body.
Treatment
As pituitary tumours are almost always adenomas (benign), there is currently no staging and grading system for these tumours. Some of the factors your doctor may consider in regard to treatment options may include:
- Tumour size.
- Metastasis (if it is not an adenoma).
- If the tumour has grown to impact portions of the brain.
- Symptoms.
- Whether it is functional or non-functional.
Your doctor may also recommend genetic testing which analyses your tumour DNA and can determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment options for pituitary tumours may include:
- Surgery, potentially including:
- Transsphenoidal surgery (removal of the tumour through an incision in the nasal cavity).
- Craniotomy (removal of the tumour through an opening in the skull).
- Radiation therapy, potentially including:
- External radiation therapy.
- Internal radiation therapy.
- Stereotactic radiation therapy.
- Chemotherapy (only used for pituitary carcinomas).
- Hormone therapy (used for functional tumours to inhibit excess hormone production).
- Watch and wait (used for asymptomatic non-functional adenomas).
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia Treatment Options page.
Risk factors
While the cause of pituitary tumours remains unknown, the following genetic conditions may increase your risk of developing the disease:
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Some of the information regarding risk factors was obtained from the Pituitary Tumors Treatment (PDQ) page published by the National Cancer Institute.
Early symptoms
The symptoms of a pituitary tumour will vary, depending on whether the tumour is functional and non-functional.
Non-functional Pituitary Tumour Symptoms
The symptoms of a non-functional pituitary tumour are related to the pressure that the tumour is putting on the brain and nearby nerves, and usually occur when the tumour reaches a certain size. This pressure can result in decreased hormone production, and may cause additional symptoms. These symptoms may include:
- Persistent headaches.
- Changes in vision, such as:
- Blurred vision.
- Double vision.
- Loss of peripheral vision.
- Blindness.
- Eye muscle weakness.
- Facial numbness and/or pain.
- Dizziness.
- Loss of consciousness.
- Loss of body hair.
- Changes in menstruation and milk production.
- Decreased sex drive.
- Delayed growth and sexual development (children).
- Seizures.
Functional Pituitary Tumour Symptoms.
The symptoms of a functioning pituitary tumour will vary based on the type of hormone being produced.
Excess Prolactin
The symptoms of excess prolactin have different effects in men and women.
Excess prolactin in women may cause the following symptoms:
- Changes in menstrual periods, such as:
- Irregular menstrual periods.
- Absence of menstrual periods.
- Less frequent menstrual periods.
- Unusually light menstrual periods.
- Abnormal breast milk production (also known as galactorrhea).
- Lowered sex drive.
- Infertility.
- Osteoporosis.
Excess prolactin in men may cause the following symptoms:
- Erectile dysfunction (also known as impotence).
- Lowered sperm count.
- Breast growth.
- Lowered sex drive.
- Infertility.
- Osteoporosis.
Excess Growth Hormone
The symptoms of excess GH have different effects in children and adults.
In children, excess GH may cause giantism, which has the following symptoms:
- Being unusually tall for age.
- Rapid growth.
- Joint pain.
- Increased sweating.
Full-grown adults cannot develop giantism, even with excess GH. However, they can develop acromegaly, which has the following symptoms:
- Growth of skull, hands and feet. This may cause an increase in hat, shoe, glove and/or ring size.
- Changes in vision and/or voice.
- Changes in facial appearance (such as wider spacing of teeth and/or jawbone growth).
- Joint pain.
- Increased sweating.
- High blood sugar.
- Kidney stones.
- Heart disease.
- Tingling and/or numbness in the hands and fingers.
Excess ACTH
Excess ACTH may cause Cushing’s disease, or hypercortisolism, which have different effects in adults and children.
In adults, the symptoms of Cushing’s disease include:
- Unexplained weight gain (particularly in face, chest and abdominal areas).
- Exaggerated facial roundness.
- Thinning of arms and legs with muscle weakness.
- Pink or purple stretch marks on the chest and/or abdomen.
- Easy bruising.
- New or increased hair growth.
- Acne.
- High blood sugar.
- High blood pressure.
- Weakening of bones, which may cause osteoporosis or easily broken bones.
- Anxiety, irritability and/or depression.
Children can develop many of the same symptoms as adults with the disease. In addition to this, they may also experience:
- Delayed growth.
- Difficulty concentrating.
Excess LH & FSH
These tumours are incredibly rare, and may appear asymptomatic in the earlier stages of the disease. In most cases, they will cause the same issues as non-functioning adenomas before excess LH and FSH are produced. If the tumour becomes large enough to produces excess hormones, you may also experience the following symptoms:
- Irregular menstrual periods (women).
- Low testosterone levels (men).
- Decreased sex drive.
Excess TSH
Excess TSH may cause hyperthyroidism, which has the following symptoms:
- Unexplained weight loss.
- Rapid or irregular heartbeat.
- Nervousness, anxiety and/or irritability.
- Tremors (shaking).
- Frequent bowel movements.
- Excessive sweating.
- A large lump in the front of the neck (enlarged thyroid gland).
Not everyone with the symptoms above will have cancer but see your GP if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have a pituitary tumour, they will order a variety of diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.
Neurological exam
A neurological examination assesses sensory and motor functions, and can generally be done in your GPs office. The doctor may check your vision, hearing, balance, coordination, strength and reflexes, depending on the signs and symptoms you have described.
Endocrine studies & blood tests
Endocrine studies involve blood and/or urine tests and imaging tests (see below) to analyse your hormone levels and detect any abnormalities. Some of these tests may include:
- General blood test to assess overall health.
- Blood tests to measure levels of:
- Glucose.
- Oestrogen.
- Testosterone.
- Prolactin.
- GH.
- ACTH.
- TSH.
- LS and FSH.
- 24-hour urine test, which measures levels of cortisol levels in your urine.
- High-dose dexamethasone suppression test.
- Low-dose dexamethasone suppression test.
Imaging tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), and/or positron emission tomography (PET scan), depending on where it is suspected the tumour is. The doctor may also look at other parts of the body and look for signs of metastasis, which can determine if you have an adenoma or a cancerous tumour.
Biopsy
Once the location of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. In most cases, this may be done by either an excision biopsy (where the lymph node is completely or partially removed), a fine needle biopsy (a fine needle is inserted into the lymph node to remove a sample), or a core needle biopsy (where a bigger needle is inserted into the lymph node to remove a sample). Both of these procedures are often performed as a day surgery.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage paragangliomas have good prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.