Cushing’s disease is caused by tumors in the pituitary gland, which produces many important hormones that regulate body processes. This includes the adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to produce cortisol.
When a tumor causes the pituitary gland to produce too much ACTH, the adrenal gland produces too much cortisol in response. This can lead to symptoms such as weight gain, high blood sugar, high blood pressure, and bone thinning.
The first choice of treatment for Cushing’s disease is to surgically remove the pituitary tumor via a transsphenoidal adenomectomy. Second-choice options include removing the adrenal glands, destroying tumor cells with radiation therapy, and using medications to lower cortisol levels or block cortisol’s effects in the body.
During transsphenoidal adenomectomy, the surgeon accesses the pituitary either through the nostril or upper lip. The sphenoid sinus is a hollow cavity that sits above the nose and below the pituitary gland. The surgery successfully reduces cortisol and relieves symptoms in about 70% to 90% of patients, with a higher success rate for smaller tumors. Sometimes tumors return, often because the first surgery left behind some tumor tissue, and a second surgery is necessary. Sometimes doctors need to pair surgery with another form of treatment, such as radiation therapy or medication.
Some patients need cortisol replacement following surgery, until the body can naturally maintain healthy cortisol levels.
Adrenal gland removal
Another way to bring down cortisol levels is to remove one or two of the adrenal glands. Adrenal gland removal is almost always effective, but in most cases, patients must take cortisol replacement therapy for the rest of their lives. (Although too much cortisol causes problems, the body needs cortisol to work properly).
The adrenal glands also make aldosterone, a hormone that controls the balance of salt and water in the body. Patients whose adrenal glands are removed must also take Florinef (fludrocortisone) to replace aldosterone.
Radiation therapy involves focusing high-energy X-ray beams on a tumor to destroy and shrink it. This is the first treatment for patients who are not candidates for surgery, and as a second treatment when surgery fails to completely remove the tumor. Surgeons may also use this for larger tumors before surgery, to shrink the tumor to improve the chances of successful removal.
Radiation therapy carries a higher risk than surgery of damaging other areas of the pituitary. It also takes longer — up to 10 years — to fully restore cortisol balance and reverse symptoms following radiation therapy. During this time, doctors use medications to help control cortisol production. Standard radiation therapy to treat pituitary tumors requires multiple treatments over five to six weeks.
Stereotactic radiation therapy, or stereotactic radiosurgery, is another type of radiation therapy that targets the pituitary tumor more precisely. It uses a frame to restrain the head so doctors can direct the radiation to the exact location of the tumor. Unlike conventional therapy, stereotactic therapy applies a large dose of radiation in a single treatment, reducing the risk of harming surrounding tissue.
Radiation can destroy other hormone-producing cells in the pituitary, so patients may need replacement therapy with thyroid hormones, growth hormones, sex hormones, or hormones that help control blood pressure such as vasopressin.
Medications may help to control cortisol levels, usually in combination with surgery or radiation therapy. They may also be used as a first treatment when neither surgery nor radiation are good options. Medications for Cushing’s disease may target the adrenal glands, the pituitary glands, or cortisol receptors. Treatments that use a combination of medications can improve success because the medicines target different sites to control cortisol balance.
Lysodren (mitotane) and Metopirone (metyrapone) work on the adrenal gland to lower cortisol levels. Signifor (pasireotide) and cabergoline work on the pituitary to decrease levels of ACTH. Korlym (mifepristone) blocks the effects of cortisol on tissues by blocking cortisol receptors. Isturisa (osilodrostat) inhibits one of the enzymes that is involved in making cortisol in the body, which reduces cortisol production.
Several new experimental medications are also being explored to treat Cushing’s disease.
Last updated: April 20, 2020
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