Pituitary tumors are abnormal growths that develop in the pituitary gland, which is a small pea-sized gland located at the base of the brain. The pituitary gland is responsible for producing and regulating hormones that control many bodily functions, such as growth, metabolism, reproduction, and stress response.
Types of Pituitary Tumors
There are two main types of pituitary tumors –
- Functioning Pituitary Tumors: These tumors secrete excess hormones, causing hypersecretion syndromes. Depending on the specific hormone secreted, functioning pituitary tumors can be classified into several subtypes:
- Prolactinoma: The most common type of functioning pituitary tumor, which secretes prolactin and can lead to menstrual irregularities, galactorrhea (abnormal lactation), and decreased libido in both men and women.
- Growth hormone-secreting tumor (GHoma): This type of tumor secretes growth hormone, causing gigantism or acromegaly (an enlargement of the hands, feet, and other facial features).
- Adrenocorticotropic hormone-secreting tumor (ACTHoma): This type of tumor secretes ACTH, causing Cushing’s disease (a collection of symptoms caused by excess cortisol in the body).
- Thyrotropin-secreting tumor (TSHoma): This type of tumor secretes TSH, causing hyperthyroidism.
2.Non-functioning Pituitary Tumors: These tumors do not secrete hormones, or they secrete hormones in amounts that do not cause clinical symptoms. Non-functioning pituitary tumors can be further classified into:
- Null cell adenomas: These tumors do not produce any known pituitary hormones.
- Silent gonadotroph adenomas: These tumors produce low levels of hormones such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which regulate reproductive function.
- Oncocytomas: These tumors are rare and may cause vision problems due to their size and location, but they do not produce hormones.
The symptoms of a pituitary tumor can vary depending on the size and type of the tumor. Some common symptoms of pituitary tumors include –
- Headaches: These may be severe and may not respond to typical headache remedies.
- Vision problems: The tumor can press on the optic nerve and cause vision loss, blurred vision, or double vision.
- Hormonal imbalances: Depending on the type of pituitary tumor, hormonal imbalances can cause a range of symptoms including –
- Prolactinoma: It causes excessive milk secretion from the breasts (galactorrhea), irregular periods, infertility, decreased sex drive
- Growth hormone-secreting tumor: leads to acromegaly or gigantism, enlarged hands, and feet, coarsened facial features, snoring or sleep apnea, joint pain
- Adrenocorticotropic hormone-secreting tumor: It can cause weight gain, high blood pressure, diabetes, muscle weakness, thinning skin, purple stretch marks
- Thyrotropin-secreting tumor: hyperthyroidism, weight loss, rapid heartbeat, anxiety, sweating.
- Fatigue and weakness: These can be caused by a hormonal imbalance or the physical presence of the tumor.
4. Nausea and vomiting: These can be caused by the pressure of the tumor on the brain or hormonal imbalances.
5. Mood changes: The hormonal imbalances caused by a pituitary tumor can also affect mood, causing depression, anxiety, or irritability.
These symptoms can be caused by other conditions, and having one or more of these symptoms does not necessarily mean that a person has a pituitary tumor. It is important to consult a doctor if any of these symptoms occur or persist for a long time.
Causes and Risk Factors
The causes of pituitary tumors are yet unknown, but there are several risk factors that may increase the likelihood of developing one. Some of these factors include –
- Age: Pituitary tumors are most commonly diagnosed in people over the age of 50, but they can occur at any age.
- Gender: Certain types of pituitary tumors, such as prolactinomas, are more common in women.
- Family history: Some pituitary tumors may be hereditary, and having a family member with a pituitary tumor may increase the risk of developing one.
- Genetic conditions: Certain genetic conditions, such as multiple endocrine neoplasia type 1 (MEN1), can increase the risk of developing pituitary tumors.
- Radiation exposure: Exposure to radiation, particularly to the head and neck, may increase the risk of developing a pituitary tumor.
- Hormonal imbalances: Certain hormonal imbalances, such as those associated with conditions like acromegaly and Cushing’s disease, can increase the risk of developing a pituitary tumor.
These risk factors may increase the likelihood of developing a pituitary tumor, but that does not mean people with these risk factors will develop pituitary tumors. Also, many people with pituitary tumors have no identifiable risk factors in the early stages of cancer unless it is identified through imaging tests and blood tests.
The stages of pituitary tumors are typically classified based on the tumor size and extension, and are as follows –
- Microadenomas: These are small pituitary tumors less than 1 cm in size. They are usually benign and do not spread to other parts of the body.
- Macroadenomas: These are larger tumors that are greater than 1 cm in size. They may cause symptoms such as headaches, vision problems, and hormonal imbalances. These tumors can be further classified into two categories –
a. Non-invasive macroadenomas: These tumors do not invade the surrounding tissues and are confined to the pituitary gland.
b. Invasive macroadenomas: These tumors invade the surrounding tissues, such as the bones of the skull or the cavernous sinus, a space located behind the eyes.
- Giant adenomas: These are pituitary tumors that are more than 4 cm in size. They can cause severe symptoms due to their size and may require surgical intervention.
- Carcinomas: These are rare malignant tumors of the pituitary gland that can spread to other parts of the body. They are very aggressive and can be difficult to treat.
Pituitary tumors are often diagnosed using a combination of imaging tests and hormone level measurements. Here are some common diagnostic tests for pituitary tumors –
- Blood tests: Blood tests can be used to measure hormone levels. Pituitary tumors can cause overproduction or underproduction of hormones, and measuring hormone levels can help diagnose and monitor the tumor.
- Imaging tests: Imaging tests such as magnetic resonance imaging (MRI) or computed tomography (CT) scans can provide detailed images of the pituitary gland and the surrounding tissues. These tests can help identify the size and location of the tumor, as well as any changes in the gland or surrounding tissues.
- Vision tests: Pituitary tumors can press against the optic nerve, causing vision changes. Visual field testing or a complete eye exam may be recommended to assess any changes in vision.
- Biopsy: In rare cases, a biopsy may be necessary to confirm the diagnosis of a pituitary tumor. During a biopsy, a small tissue sample is removed from the tumor and examined under a microscope.
The diagnostic tests with a healthcare provider who specializes in the diagnosis and treatment of pituitary tumors, as the best course of action will depend on individual factors.
The treatments will be determined by your healthcare provider on the basis of age, medical history, condition, and preferences. The treatments recommended by doctors for pituitary tumors are –
- Surgery – It is often the best choice for the removal of tumors. The surgery is usually performed through the nose or through a small incision in the skull.
There are 2 types of surgery performed on the basis of type, location, and size of tumor including –
- Transsphenoidal surgery – The surgery is performed through the sphenoid sinus i.e a hollow space in the skull behind the nasal passages and the brain. It is specifically used for small tumors as no part of the brain gets affected during this surgery. It also causes fewer side effects compared to craniotomy surgery.
- Craniotomy – If the pituitary tumor is large and complicated then craniotomy may be needed. The front of the skull is removed to perform this surgery. It is a complex procedure that requires an expert surgeon to better see and reach the tumor with all the nearby nerves and blood vessels.
2. Medications: Medications may be prescribed to shrink the tumor or to control hormone levels. For example, dopamine agonists may be prescribed for prolactin-secreting tumors, and somatostatin analogs may be prescribed for growth hormone-secreting tumors.
3. Radiation therapy: Radiation therapy may be used to shrink the tumor or to destroy any remaining tumor cells after surgery. It may be used as the primary treatment for some tumors that cannot be removed with surgery.
There are 2 main types of radiation therapy –
- Fractionated radiation therapy – The dose of radiation is broken into smaller doses that are usually given 5 times a week for a period of 4 to 6 weeks.
- Stereotactic radiosurgery – is a type of radiation therapy that uses a highly focused radiation beam to deliver a high dose of radiation to the location of the tumor. It is typically given in a single treatment session and may be used for smaller tumors that are not causing significant symptoms.
4. Combination therapy can also be performed by your healthcare professional if found necessary for your underlying condition. It involves using a combination of medications, surgery, and radiation therapy, which may be necessary to treat some types of pituitary tumors.
The prognosis or long-term outlook for pituitary tumors can be determined by several factors such as the type of tumor, the person’s age, and the spread of cancer cells in other parts of the body.
Based on the statistical reports, 16% of patients with non-functioning tumors will have a tumor recurrence within 10 years after receiving treatments. And 10% of patients require additional treatments or a combination approach to stop the growth of cancer cells in the body.
If you’ve been diagnosed with a pituitary tumor, it is necessary to work closely with your healthcare provider to determine the best individual treatment plan for your individual case and also to discuss your long-term outlook.