Cancer rate not elevated for adults with acromegaly
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Adults treated for acromegaly at a medical center in Turkey do not have an increased risk for cancer compared with the general population, according to study findings published in Endocrine Practice.
“It is well known that insulin-like growth factor I has mitogenic and antiapoptotic activity,” Muhammed Kizilgul, MD, associate professor and clinical endocrinologist in the department of endocrinology and metabolism at University of Health Sciences, Diskapi Yildirim Beyazit Training and Research Hospital in Ankara, Turkey, told Healio. “Animals and humans with congenital growth hormone deficiency or resistance struggle to protect themselves from several types of cancer, and these models are accepted as the strongest evidence in terms of GH’s role in carcinogenesis. Despite well-described pathophysiologic mechanisms of carcinogenesis in acromegaly, the clinical importance of these findings remains controversial. There are many studies [that have] concluded that cancer risk is increased in patients with acromegaly. However, some recent studies found similar cancer rate with the general population, with which our results are concordant.”
Kizilgul and colleagues conducted a retrospective study of 280 adults with acromegaly (57% women; mean age, 51 years) who were followed after surgery at Diskapi Training and Research Hospital and Numune Training and Research Hospital between 2010 and 2019. The study cohort was split into groups with and without cancer. Standard incidence rates for cancer were calculated by dividing the number of cancer cases in the study cohort by the expected number of cases. Expected cancer cases were calculated using public health cancer data from the Ministry of Health in Turkey from 2010 to 2019. Demographics, acromegaly duration, pituitary adenoma size, treatment choice and disease status at time of diagnosis were analyzed. GH and IGF-I concentrations were measured for all participants, and serum IGF-I levels were compared with age- and sex-adjusted reference values.
Among the cohort, 19 were diagnosed with cancer. Thyroid cancer was the most common, present in nine of 19 adults with cancer. There was no significant difference in the prevalence of cancer among men or women with acromegaly compared with the general population.
Those in the cancer cohort had an older current age than those without cancer (56.7 years vs. 50.5 years; P = .048). The age at acromegaly diagnosis was similar in both groups, as was time to diagnosis, disease duration, and basal and current GH and IGF-I levels. GH and IGF-I levels were also similar in those with and without thyroid cancer. There was no significant difference in the prevalence of active disease between the group with cancer and the noncancer group.
Kizilgul said varying methods for measuring the risk for cancer in acromegaly may explain why the findings differ from previous research.
“Acromegaly and cancer risk have been evaluated from two different basic perspectives,” Kizilgul said. “Patients with acromegaly were followed for a long period and cancer rates were compared to those in the general population in the first method. In the second method, a cross-sectional analysis was used to compare a cohort of patients with acromegaly with matched controls. It is likely to encounter a considerably higher estimate of cancer risk in the second method in comparison with the first one, and the results of the many studies concluding higher cancer risk in acromegaly patients might suffer from this bias. We compared the cancer rate in our patients with the cancer rate in general population, which is consistent with the first method.”
Kizilgul said prospective, controlled longitudinal studies are needed to analyze whether there is a causal relationship in acromegaly with malignant cancer. He also said a national register of incidences of neoplasms in people with acromegaly is needed.
For more information:
Muhammed Kizilgul, MD, can be reached at muhammedkzgl@gmail.com.
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