Surgical view of an adrenal tumor within the "Bermuda Triangle" of the abdomen.
We will begin this section with the assumption that the presence of an adrenal tumor has already been confirmed with either blood testing, special imaging or both. There are two questions that must be answered next:
BENIGN VS. MALIGNANT
While only approximately 15% of canine Cushing’s syndrome patients have adrenal tumors, half of these patients will have benign tumor and half will have malignant tumors. The choice of therapy may well depend on which is present.
If imaging has not yet been performed, this is the time to do so. Chest radiographs will be important as malignant adrenal tumors tend to spread to the chest. If such spread is seen, the tumor can be assumed to be malignant. Absence of such findings does not mean the tumor is benign. Ultrasound of the abdomen, if this has not already been done, (or even CT scanning, MRI imaging, or nuclear medicine scanning) will be needed to determine the size of the tumor, and to check for invasion of local abdominal tissues (especially liver).
Between evaluation of the chest and the abdomen, it may be possible to non-invasively determine if the tumor is malignant. It should be noted that the absence of tumor spread does not mean that the tumor is benign. If there is obvious spread to other organs, medical management is the only meaningful hope for the patient. It may be necessary to consult with an oncologist for the most current medication plan.
WHAT IF IMAGING FAILS TO CONFIRM THAT THE TUMOR IS MALIGNANT?
As mentioned, it is not possible to say that the tumor is benign simply because tumor spread has not been detected. Still, no evidence of spread is about as close to determining that the tumor is benign as we can get without actually obtaining tissue samples. If the adrenal tumor is benign, there is an excellent chance for complete recovery if the tumor is surgically removed. The smaller the tumor, the easier the surgery, though the surgery involves delicate tissue in a difficult area.
WHAT IF IMAGING INDICATES THAT THE TUMOR IS MALIGNANT?
If there is obvious tumor spread, surgery may be too risky. The decision to proceed with medical therapy will depend on patient debilitation and the degree of tumor spread versus the severity of the clinical signs of Cushing’s disease. Palliation of the clinical signs may be achieved with just partial removal of the tumor. Medical management with trilostane or with high doses of lysodren would be fair alternatives.
WHAT YOU SHOULD KNOW ABOUT SURGERY
MEDICAL THERAPY FOR THE ADRENAL TUMOR
As can be seen from the above discussion, adrenalectomy is a high risk surgery. It may not be a good choice for an elderly debilitated patient, especially if the tumor is large or has evidence of spread. Further, a 24 hour specialty center is needed for this sophisticated procedure and these centers may not be accessible and there is a great deal of expense involved in a surgical adventure of this magnitude. For these reasons, medical management may be selected as an alternative.
Lysodren is a drug of chemotherapy which is able to erode the cortisol-producing layers of the adrenal gland. This ability hs made lysodren, the traditional medication for the treatment of pituitary Cushing’s disease and it turns out the adrenal tumors will respond to higher doses as well. The higher doses needed to control adrenal tumors tend to produce more lysodren reactions than are seen in the treatment of pituitary tumors. The average survival time for this type of therapy is 16 months.
For a review of the basics of lysodren therapy click here.
Trilostane can also be used for functioning adrenal tumors though it will not actually erode adrenal tissue (which could potentially erode the tumor). Trilostane acts by inactivating excess steroid hormones and thereby managing the symptoms of Cushing's disease. One would think that this would not be effective since it does not directly affect the tumor but at least one study showed a comparable survival time to that of patients on lysodren. As with lysodren, a special protocol is needed that is different from the protocols using the same drugs in the treatment of pituitary-dependent Cushing's disease.
For a review of the basics of trilostane therapy click here.
Page last updated: 5/1/2018