Incidence of Cushing’s disease may be increasing in Iceland: Study
17 new cases identified from 2010 to 2019
Cushing’s disease appears to be on the rise in Iceland, a study finds, underscoring the importance of an early diagnosis.
“Advances in diagnostic and treatment options is probably the strongest cause of increased incidence in the later years, but other factors such as genetics can also play a role,” the researchers wrote in the study, “Cushing’s disease may have higher incidence than previously thought: A nationwide study in Iceland 2010-2019,” which was published in Neuroendocrinology.
Cushing’s disease is caused by a pituitary tumor in the brain that drives the adrenal glands atop the kidneys to produce excessive amounts of the hormone cortisol. This results in many symptoms, from weight gain and skin changes to muscle weakness and fatigue.
A previous study in Iceland found an average of 1.5 cases of Cushing’s disease per million people each year from 1955 to 2009. The number of cases was higher in the study period’s last decade, suggesting an increase in diagnosing or reporting the disease.
Studying rising number of cases of Cushing’s disease
The number of cases was higher than that seen in other countries, however, leading researchers to conduct a follow-up study that reviewed the incidence, or the number of new cases, of Cushing’s disease in Iceland from 2010 to 2019 to see why an increase was occurring.
The researchers reviewed medical records from the country’s only university hospital, which handles all the cases of Cushing’s disease. Specialists skimmed through the records to ensure data were accurate and included details about patient demographics, diagnosis, and treatment.
From 2010 to 2019, 17 new cases of Cushing’s disease were identified (12 females, five males), for an overall incidence of 5.2 cases per million people per year. The mean age at diagnosis was 46 and ranged from 13 to 85.
“Even though the population in Iceland is relatively small compared to other reporting countries, all cases with [Cushing’s disease] are diagnosed and/or treated at the only university hospital in Iceland, making the annual incidence report very complete,” the researchers wrote.
Imaging studies showed 12 (71%) patients had a visible tumor in their pituitary gland. Almost all (94%) underwent transsphenoidal surgery to remove the tumor through the nasal passages to minimize damage to the surrounding structures.
Four (24%) patients needed additional gamma knife radiosurgery, a type of radiation therapy that uses gamma rays to eliminate tumor cells. Three (18%) had a adrenalectomy to remove the adrenal glands after transsphenoidal surgery was unsuccessful. The patients were followed for a median of 99 months, or just over eight years. Three years after the diagnosis, 13 (76%) patients showed no signs of excess cortisol and, by the end of the study, 15 (88%) had no evidence the disease had returned. Two patients died.
“The study emphasizes the importance of being alert for [Cushing’s disease] as the incidence appears to be higher than doctors have anticipated over the world,” the researchers wrote.
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