What is Adrenal Metastasis?
Adrenal metastases, which are cancerous growths, are the most common harmful abnormalities found in the adrenal glands. These are second only to benign (non-cancerous) adenomas. Originally, these metastases were mostly identified during autopsies. However, as CT, MRI, and PET scans have become more common tools for diagnosing, staging, and monitoring cancers, incidental findings of adrenal metastases have become more frequent.
What Causes Adrenal Metastasis?
Despite their relatively small size, adrenal glands are the fourth most common place where cancer spreads, making it a significant site in malignant diseases. The adrenal glands can take in cancer cells originating from different body parts. In most cases, these cells come from the lung (39% of cases) or the breast (35%). Other sources of these cells include skin cancer (melanoma), the digestive system (gastrointestinal tract), pancreas, and kidney, among other places.
Risk Factors and Frequency for Adrenal Metastasis
Adrenal masses are often discovered incidentally, and in those with a history or recent diagnosis of cancer, about 30% to 70% of these growths are actually metastases, or cancer that has spread from a different area of the body. This number may actually be higher when performing autopsies. This was demonstrated in a study where they found the rate of adrenal metastases from kidney cancer was between 6% and 29% in autopsies, but only 2% to 10% in regular clinical diagnoses.
The time from the initial cancer diagnosis to finding adrenal metastases is typically around 2.5 years. However, they have been found as much as 22 years after the initial treatment of the primary cancer. Usually, the primary cancer is found before any adrenal metastases. The rates of adrenal metastases have increased with the rising incidences of breast and lung cancers, among other types.
Signs and Symptoms of Adrenal Metastasis
Adrenal metastases, or the spread of cancer to the adrenal glands, often show no symptoms. When symptoms do occur, they can include localized back or stomach pain. This pain can be caused by a large or rapidly growing tumor. This may signal either local invasion by the cancer or internal bleeding in the abdominal cavity.
It’s rare for adrenal metastases to lead to adrenal insufficiency. This usually only happens if a majority (more than 90%) of both adrenal glands are affected. When this happens, symptoms can include:
- Loss of appetite
- Weight loss
- Nausea
- Vomiting
- Stomach pain
- Weakness
- Fatigue
- Drowsiness
- Fever
- Confusion
- Abnormal levels of electrolytes due to the lack of adrenal function
These symptoms can often be mistaken for symptoms of the cancer itself. Rarely, a crisis can occur due to symptomatic bleeding into the adrenal glands that have been affected by metastatic cancer.
Testing for Adrenal Metastasis
If a patient has cancer spread to the adrenal glands (also known as metastases), this tends to influence how we manage and treat the initial cancer. We often need to conduct further evaluation, particularly if the cancer hasn’t spread to any other parts of the body except the adrenal glands.
Imaging tools we can use to detect and evaluate adrenal tumors include CT scans, MRI scans, and FDG-PET/CT scans. Currently, we don’t have a single gold standard imaging tool because no one method can determinely evaluate adrenal incidentalomas or conclusively separate benign (non-cancerous) from malignant (cancerous) adrenal masses.
CT and MRI scans mainly differentiate benign from potentially cancerous adrenal masses by assessing lipid content. FDG-PET/CT scans are mainly used to detect cancerous tumors. Still, they may also yield false positive results (detecting non-cancerous tumor as cancerous) and false negative results (failing to identify small cancer spots).
Sometimes, when imaging results are unclear, a biopsy may be necessary. For this, we use a CT-guided fine-needle aspiration, which is when a needle is used to remove cells from the tumor to be examined under a microscope. This allows us to have definitive proof of what we are dealing with. However, it’s essential to ensure that adrenal tumors called pheochromocytomas are ruled out before the biopsy is done as they can cause hypertensive crisis, a rapid increase in blood pressure that could be life-threatening.
Finally, it’s important to bear in mind that not all adrenal tumors are cancerous or cause symptoms. Doctors use biochemical evaluation or tests to rule out pheochromocytoma in individuals with potential metastatic adrenal glands. In some rare cases, adrenal metastases can cause adrenal insufficiency. In these cases, stress dose glucocorticoids should be strongly considered to prevent adrenal crisis in patients with cancer history and use of glucocorticoids as part of chemotherapy regimen or other treatment in the past year.
Treatment Options for Adrenal Metastasis
The best way to treat adrenal metastases, or cancer that has spread to the adrenal glands, is to first target the original cancer. This is typically done using chemotherapy and/or radiation therapy. Surgery to remove the adrenal tumors is an option if the patient only has adrenal metastases or other metastases that can potentially be cured.
A PET scan can be very helpful in detecting if the cancer has spread to the adrenals only and in making sure there’s no cancer spread elsewhere in the body. This will be particularly useful if a CT or MRI scan hasn’t already identified any other metastases. If the cancer hasn’t invaded nearby structures and there has been a period of at least six months since first being diagnosed with the original cancer, the odds of having a successful outcome with adrenal surgery are generally good. The results of surgery can still vary depending on where the cancer originally started. There’s no proof that doing this surgery helps if doctors don’t know where the cancer started.
Minimally invasive laparoscopic surgery can be an effective method for removing adrenal tumors. This surgical approach is associated with less postoperative pain, fewer complications, and a shorter hospital stay.
Small adrenal masses measuring less than 6 cm that aren’t invading nearby structures can also be removed through laparoscopic surgery. Other treatments like radiotherapy, radiofrequency ablation, arterial ablation, chemoablation, cryoablation, and thermal ablation guided by CT or MRI have shown variable results and can be used for curative and palliative purposes.
Approaches like radiofrequency ablation, cryoablation, and microwave ablation that use heat to destroy adrenal tumors could help control the local tumor. But there are risks involved, such as the development of severe high blood pressure and adrenal insufficiency. Using drugs called alpha blockers before the ablation has been found to reduce the high blood pressure episodes but may necessitate the use of medications called vasopressors during the procedure. It’s crucial to evaluate adrenal function after the ablation and start glucocorticoid replacement therapy if needed, to avoid serious health consequences due to adrenal insufficiency.
What else can Adrenal Metastasis be?
- Amyloidosis of the adrenal gland (A condition where abnormal proteins build up in your adrenal gland)
- Adrenal incidentaloma (An unexpected lump or tumor in the adrenal gland discovered during an imaging test for an unrelated condition)
- Adrenal hamartoma (A benign or non-cancerous growth in the adrenal gland)
- Adrenal myelolipoma (A non-cancerous tumor in the adrenal gland that’s made up of fat and bone marrow cells)
- Adrenal teratoma (A rare type of tumor in the adrenal gland made up of a mix of different types of cells)
- Imaging for Neuroblastoma (A way to visualize a type of cancer that typically affects children and originates from certain nerve cells)
- Pancreatic cancer (A type of cancer where cells in the pancreas grow uncontrollably)
- Plexiform neurofibromas (A complex, usually non-cancerous tumor associated with a genetic disorder called neurofibromatosis)
- Renal cell carcinoma (The most common type of kidney cancer)
