What causes adrenal cortical cancers and am I at risk?
Each year, there are approximately 500 cases of adrenal cortical cancers in the United States. These most commonly occur in patients between the ages of 30 and 50; however, children under the age of 5 develop adrenal cortical cancers at a higher rate than the rest of the population. Males are more likely to develop non-functioning adrenal carcinomas, while females are more likely to develop functioning adrenal carcinomas. In general, causes of adrenal cortical cancers are unknown. They are not associated with smoking, and do not run in families. Despite this, certain genetic mutations have been associated with adrenal cortical cancers, and research is ongoing in attempt to identify the causes of these cancers.
How can I prevent adrenal cortical cancers?
Given that the causes of adrenal cortical cancers are unclear, there are no known interventions that can reduce the risk of developing them.
How are adrenal cortical cancers diagnosed, and how do you tell them apart from adrenal adenomas?
Functioning adrenal cortical cancers and adenomas are frequently diagnosed because of the symptoms caused by steroid hormones. Patients with Cushing's syndrome need to be evaluated to see if the syndrome is caused by a problem in the adrenal glands, the pituitary gland, or another tumor somewhere else in the body. The first step is measuring the amount of cortisol in the urine (called a 24-hour urinary free cortisol test). This test is sometimes performed while giving the patient an extra dose of steroids to see how the body responds. After this is done, most patients undergo a dexamethasone suppression test where patients are given a high dose of the steroid dexamethasone. In normal patients and in patients with Cushing's syndrome due to a problem in the pituitary gland, a high dose of dexamethasone will cause the levels of cortisol in the blood and urine to decrease. In patients with adrenal tumors or another tumor in the body that produces ACTH, cortisol levels remain high even after a patient receives a high dose of dexamethasone.
In patients with excess levels of aldosterone, patients should be tested for blood levels of the chemical renin. In cases of hyperaldosteronism due to a tumor in the adrenal gland, renin levels will be low. In patients who have elevated aldosterone levels due to a problem with the blood vessels of the kidney (a condition called renal artery stenosis), renin levels in the blood are high.
In addition to tests for increased steroid production, radiographic imaging is an important part of the diagnosis of adrenal tumors. Computed Tomography (CT or CAT) scans are commonly used. CT scans use x-rays to form a three-dimensional picture of the inside of the body. If the adrenal tumor is larger than 6 centimeters (cm) on CT scan, it is much more likely to be an adrenal cancer than an adrenal adenoma. In most cases, CT scans can also differentiate between a normal adrenal gland and adrenal hyperplasia.
Ultrasound is sometimes used in the diagnosis of adrenal tumors. Ultrasounds use sound waves to form a picture of the inside of the body. At times, it can be difficult to tell if an adrenal tumor is an adenoma or a cancer. For tumors that are larger than 3 cm, ultrasound is a good method of telling the difference between the two.
Another type of imaging that is used when it is unclear if an adrenal tumor is an adenoma or cancer is Magnetic Resonance Imaging (MRI). MRI uses magnets to produce a very sharp picture of the inside of the body. Certain types of changes on MRI are more commonly seen in adrenal cancers than adenomas and can be used to tell the two apart.
Positron Emission Tomography (PET) scans use radioactively labeled sugar to find rapidly growing cells within the body. When cells are dividing quickly, they require a lot of energy, and the main source of energy in the body is sugar. Areas of actively dividing tissue will require more sugar than slowly dividing tissue. Because cancer cells are rapidly dividing and growing, they take up more the radioactively sugar than the surrounding tissue and this can be detected by the PET scanner. PET scans have been very useful in detect a number of different types of cancers. Its use in adrenal cancers is still being studied.
Ultimately, the only way to tell for sure if an adrenal tumor is an adrenal adenoma or cancer, part of the tumor must be examined underneath a microscope. In most cases of tumors or cancers, this is done by obtaining a biopsy of the tumor. A small piece of the tumor is taken, usually through a needle, and examined underneath a microscope. In the case of adrenal tumors, this procedure is usually performed while the patient is undergoing a CT scan, so that the radiologist can see where the needle is going in the body. In some cases, this can also be done using an ultrasound to guide the biopsy.