Pituitary Adenoma: Staging and Treatment
What is staging for cancer?
Staging is the process of learning how much cancer is in your body and where it is. Tests like vision tests, checking your hormone levels, urine testing, biopsy, CT, and MRI scans may be done to help stage and classify your cancer. Your providers need to know about your cancer and your health so that they can plan the best treatment for you.
Staging looks at the size of the tumor and where it is, and if it has spread to other organs.
There is no official or widely used staging system for pituitary adenomas. Often, pituitary adenomas are classified as:
- Macroadenomas- Greater than or equal to 1cm in size. Can grow into the bony areas near the pituitary gland (like to the bones of the skull).
- Microadenomas- Less than 1cm in size.
Pituitary adenomas are also classified by whether they are:
- Secreting- Adenomas that make hormones, also called functional.
- Non-secreting- Adenomas that do not make hormones, also called non-functional.
Most pituitary adenomas are benign, meaning they are not cancer. Malignant (cancerous) tumors in the pituitary gland are very rare. Only about 100 cases of malignant pituitary cancer have been reported in medical literature.
Other types of tumors (both benign and malignant) can start in the pituitary gland. These include teratomas, germinomas, and choriocarcinomas.
How is pituitary adenoma cancer staged/classified?
Staging and classification of pituitary adenomas is based on:
- The size of your tumor on imaging tests and what is found after surgery.
- Any evidence of spread to other organs (metastasis).
- Whether the tumor is secreting or non-secreting.
- If it is secreting, which hormone it is releasing.
- Whether the tumor is causing any symptoms, like changes to your sight.
How are pituitary adenomas treated?
Treatment for pituitary adenomas depends on many things, like your cancer stage, age, overall health, and testing results. Your treatment may include some or all of the following:
- Radiation Therapy.
- Stereotactic Radiosurgery.
- Treatment with Medications.
- Clinical Trials.
Malignant pituitary adenomas are often treated with surgery and radiation therapy.
Surgery is the common treatment for pituitary adenomas.
- Surgery for non-secreting macroadenomas: Removes excess tissue and relieves pressure from the adenoma on nearby tissues.
- Surgery for hormone-secreting adenomas: Surgery often helps slow down the amount of hormone being made.
Surgery for pituitary tumors can be done in a few ways:
- Transsphenoidal surgery: The most common surgery for pituitary adenomas. An incision (cut) is made on the inside of the upper lip just above the teeth, or along the septum (bridge) of the nose. The surgeon makes a cut through the base of the sphenoid sinus to get to the pituitary gland.
- For microadenomas, this surgery has high cure rates with few side effects. Sometimes, this surgery can lead to less hormone being made by the pituitary gland, leaks of cerebral spinal fluid leading to meningitis, and loss of vision. These side effects are rare and happen in less than 1% of surgeries done by an experienced neurosurgeon.
- The approach is less optimal for larger tumors, particularly macroadenomas that are very fibrous or are too far towards the back of the head.
- Endoscopic surgery: Uses a fiberoptic camera (the endoscope) to make a small incision or hole. The surgeon can get to the pituitary fossa through the nostril (nose). Small instruments are passed through the small hole and used to remove the pituitary adenoma. This surgery works well for small tumors. It is less invasive than a transsphenoidal surgery, with quicker recovery time and a low rate of side effects. This procedure may not be helpful for larger tumors or tumors that are not in a good position.
- Craniotomy: This is used for larger tumors that extend beyond the normal pituitary gland. The neurosurgeon makes cuts through the bones of the skull to get to the pituitary gland. There is a higher risk of neurologic side effects and a longer recovery time as compared to the other surgeries.
Central diabetes insipidus is a common side effect of any surgery for the pituitary gland. In diabetes insipidus, the pituitary gland does not make enough anti-diuretic hormone (ADH), which leads to too much loss of water in the urine. In most cases of diabetes insipidus after surgery, the problem goes away by itself after one to two weeks. Sometimes this problem can be permanent. To treat it, you need to take an ADH replacement (also known as vasopressin), often as a nasal spray.
Radiation treatment is the use of high-energy x-rays to kill cancer cells. Pituitary tumors can be well controlled with radiation therapy, but radiation does not remove the pressure that macroadenomas place on nearby structures as surgery does, and hormone levels fall more slowly after radiation therapy than they do after surgery. In most cases, radiation therapy is only given to patients who have cancer left behind after surgery, for patients who have their pituitary adenoma come back after surgery (recurrence), for patients whose adenomas are not in a good position for surgery, or in patients who would not tolerate surgery.
Stereotactic radiosurgery delivers radiation therapy to brain tumors in a very precise way. This method treats a tumor with large doses of radiation over a few days, or even in a single treatment, rather than spreading the treatment out over a number of weeks. This technique can deliver high doses of radiation to a specific area of the brain while lowering the amount of radiation that is delivered to healthy brain tissue.
Stereotactic radiosurgery has been tested in treatment of pituitary adenomas. Stereotactic radiosurgery helps lower hormone levels of secreting adenomas quickly. However, since higher doses are delivered with each treatment, more side effects have been seen with stereotactic radiosurgery, especially damage to the optic nerves. For this reason, stereotactic radiosurgery is not often used to treat pituitary adenomas. Sometimes, stereotactic radiosurgery can be used when a pituitary adenoma has recurred (come back after treatment).
Treatment with Medications
For some pituitary adenomas that secrete hormones (functional adenomas), treatment with medication rather than surgery or radiation can be helpful. In these cases, medications are often the first treatment.
- For pituitary adenomas that make the hormone prolactin, the medications most used are bromocriptine (Parlodel) and cabergoline (Dostinex). Lisuride and pergolide mesylate have also been used. These medications are similar to a chemical made in the brain called dopamine, which normally prevents the pituitary gland from making prolactin until it is needed. The result is less prolactin being made in the pituitary adenoma. This can shrink the tumor in most patients. The shrinking takes days to months. If the medication is stopped, the adenoma will go back to making prolactin and can grow again. Medication therapy for a prolactin-secreting pituitary adenoma needs lifelong treatment.
- Pituitary adenomas that make growth hormones can be treated with drugs such as octerotide, lanreotide, pasireotide (somatostatin analogs), or pegvisomant (growth hormone antagonist). In general, these medications work to slow down or stop the production of certain hormones in the body.
You may be offered a clinical trial as part of your treatment plan. To find out more about current clinical trials, visit the OncoLink Clinical Trials Matching Services.
Making Treatment Decisions
Your care team will make sure you are included in choosing your treatment plan. This can be overwhelming as you may be given a few options to choose from. It feels like an emergency, but you can take a few weeks to meet with different providers and think about your options and what is best for you. This is a personal decision. Friends and family can help you talk through the options and the pros and cons of each, but they cannot make the decision for you. You need to be comfortable with your decision – this will help you move on to the next steps. If you ever have any questions or concerns, be sure to call your team.
You can learn more about pituitary cancer at OncoLink.org.
American Cancer Society, http://www.cancer.org/cancer/pituitarytumors/index
Cancer.Net, Pituitary Gland Tumor: Statistics, https://www.cancer.net/cancer-types/pituitary-gland-tumor/statistics
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