Successful treatment of feline hyperadrenocorticism with pituitary macroadenoma using radiation therapy: a case study.

A 10-year-old castrated male cat showing behavioral (irritation, prowling, and tumbling) and cutaneous abnormalities such as dermal fragility was diagnosed as hyperadrenocorticism with pituitary macroadenoma, concurrent with insulin dependent diabetes mellitus. Pituitary enlargement (18.0 mm) was observed during magnetic resonance imaging. High endogenous adrenocorticotropic hormone levels (>2,500 pg/ml) were also observed. Although trilostane treatment (5-10 mg/head, daily) was commenced, the clinical signs did not disappear. Insulin and trilostane treatment were discontinued on day 86 after first day of radiation therapy (4 Gy/12 fractions). After radiation therapy, a decreased pituitary tumor size (10.7 mm) was observed on day 301; neurological and dermatological signs exhibited remission. Radiation therapy is the treatment of choice for feline hyperadrenocorticism with pituitary macroadenoma with neurological signs.

Long-term survival with stereotactic radiotherapy for imaging-diagnosed pituitary tumors in dogs.

Published studies on the use of stereotactic radiotherapy for dogs with pituitary tumors are limited. This retrospective observational study describes results of stereotactic radiotherapy for 45 dogs with imaging-diagnosed pituitary tumors. All dogs were treated at a single hospital during the period of December 2009-2015. The stereotactic radiotherapy was delivered in one 15 Gray (Gy) fraction or in three 8 Gy fractions. At the time of analysis, 41 dogs were deceased. Four were alive and censored from all survival analyses; one dog received 8 Gy every other day and was removed from protocol analyses. The median overall survival from first treatment was 311 days (95% confidence interval 226-410 days [range 1-2134 days]). Thirty-two dogs received 15 Gy (median overall survival 311 days; 95% confidence interval [range 221-427 days]), and 12 received 24 Gy on three consecutive days (median overall survival 245 days, 95% confidence interval [range 2-626 days]). Twenty-nine dogs had hyperadrenocorticism (median overall survival 245 days), while 16 had nonfunctional masses (median overall survival 626 days). Clinical improvement was reported in 37/45 cases. Presumptive signs of acute adverse effects within 4 months of stereotactic radiotherapy were noted in 10/45, and most had improvement spontaneously or with steroids. Late effects versus tumor progression were not discernable, but posttreatment blindness (2), hypernatremia (2), and progressive neurological signs (31) were reported. There was no statistical difference in median overall survival for different protocols. Patients with nonfunctional masses had longer median overall survival than those with hyperadrenocorticism (P = 0.0003). Survival outcomes with stereotactic radiotherapy were shorter than those previously reported with definitive radiation, especially for dogs with hyperadrenocorticism.

Effects of radiotherapy on pituitary corticotroph macrotumors in dogs: a retrospective study of 12 cases.

The efficacy of low doses of radiotherapy for the treatment of pituitary corticotroph macrotumors in dogs is evaluated retrospectively. Twelve dogs with pituitary-dependent hyperadrenocorticism and a large pituitary tumor treated with 36 Gy of radiation were included. Radiation was delivered in 12 fractions of 3 Gy over a 4- to 6-week period. Effects of radiation therapy on tumor size were assessed by computed tomography scans; a decrease was observed in 11 dogs (decrease > 50% in 6 dogs). Three dogs were reirradiated due to major tumor regrowth or a lack of tumor decrease (mean total dose: 22 Gy given in 3-Gy fractions over 3 or 4 weeks). The mean and median survival times following the initiation of radiotherapy were 22.6 months (688 days) and 17.7 months (539 days), respectively. These data are consistent with previous findings, based on high-dose radiation, showing that radiotherapy is a useful option for treating pituitary corticotroph macrotumors in dogs. Furthermore, computed tomography follow-up of the treated dogs demonstrates objectively the efficacy of radiotherapy against corticotroph tumors in dogs.

Efficacy of cobalt 60 radiotherapy in dogs with pituitary-dependent hyperadrenocorticism.

OBJECTIVE: To determine efficacy of cobalt 60 radiotherapy in dogs with pituitary-dependent hyperadrenocorticism (PDH) that have detectable tumors but no neurologic abnormalities. DESIGN: Case series. ANIMALS: 6 dogs with PDH that had a detectable pituitary mass on magnetic resonance images. PROCEDURE: Radiation was delivered in 11 fractions during a 3.5-week period for a total dose of 44 Gy. Clinical signs were evaluated, a urinalysis and ACTH stimulation test were performed, and urine cortisol-to-creatinine ratio and plasma endogenous ACTH concentration were measured before, immediately after, and 1, 3, 6, 9, and 12 months after radiotherapy. Magnetic resonance imaging was repeated 1 year after radiotherapy. RESULTS: Clinical signs of hyperadrenocorticism resolved in 3 dogs but recurred in 2 of the 3. Clinical condition of 2 dogs improved but did not return to normal. One dog did not improve. Results of ACTH stimulation tests and urine cortisol-to-creatinine ratios correlated with clinical signs. Plasma endogenous ACTH concentration transiently decreased in all 6 dogs. One year after radiotherapy, size of tumors was decreased by 25% in 2 dogs; in the other 4 dogs, tumors could no longer be detected. None of the dogs developed neurologic abnormalities. Adverse effects of radiotherapy were mild. CLINICAL IMPLICATIONS: Radiotherapy did not result in adequate control of clinical signs of hyperadrenocorticism in 5 of 6 dogs, but size of pituitary tumors was dramatically reduced. Thus, it may be reasonable to recommend radiotherapy in dogs with PDH that have pituitary tumors for which greatest vertical height is 8 mm or more.

Persistent and recurrent hypercortisolism after transsphenoidal surgery for Cushing's disease.

After transnasal operations in Cushing's syndrome persisting hypercortisolism either due to negative pituitary exploration or due to subtotal tumor removal, and recurrence of the disease after successful surgery still are challenging. We report on the therapeutic failures among 310 consecutive patients who underwent primary transsphenoidal microsurgery for Cushing's disease. In 287 patients an ACTH-producing pituitary adenoma could be detected (finding rate: 92.6%). In 264 cases remission of hypercortisolism could be attained (remission rate with adenoma 92.0%, for the whole series of primary operations 85.2%). In 23 patients no adenoma could be found despite extensive pituitary exploration (7.4%). Here, we will focus on the management of the 23/287 patients with persistent hypercortisolism after transnasal tumor operation (8.0%) and those 29 cases of the 264 patients with a remission who developed a recurrence of hypercortisolism (11.0%). In recurrent hypercortisolism we recommend transsphenoidal reoperation even when no tumor is visible in MRI. Seventeen of 24 reoperations in recurrent Cushing's disease were successful (70.8%). In persistent hypercortisolism we perform a reoperation during the same hospital stay. Nine of 16 early reoperations led to remission of hypercortisolism (56.3%). If transsphenoidal reoperation fails we indicate radiation therapy of different modalities depending on the extension and location of the tumor remnants. Bilateral adrenalectomy is proposed by us only if all other therapeutic measures failed.