Zosia Chustecka
January 30, 2014
A retrospective analysis suggests a potential therapeutic role for aspirin in the management of acoustic neuromas, which arise in the internal auditory canal and account for about 8% of all intracranial tumors.
These tumors, also known as sporadic vestibular schwannomas (sVS), are unlike most other solid tumors, in that they can be stable without tumor progression for decades. When they do grow, however, the effects can be devastating; they can damage the inner ear causing hearing loss, and can lead to brainstem compression, leading to cranial neuropathies and even death.
The new research, reported in the February issue of Otology and Neurotology, found an inverse association between aspirin use and the growth of these tumors, with about half the growth seen among regular aspirin users compared with nonusers. This is the first time this finding has been reported.
“Our results suggest a potential therapeutic role for aspirin in inhibiting vestibular schwannoma growth,” said lead investigator Konstantina Stankovic, MD, PhD, an otologic surgeon at the Massachusetts Eye and Ear Infirmary, and professor of otology and laryngology at the Harvard Medical School in Boston.
“Our results are correlative but not yet sufficient to start recommending aspirin for treatment of these tumors. We really need a definitive prospective study based on our retrospective analysis,” Dr. Stankovic told Medscape Medical News. Such a study is “needed but may be tricky to perform given how prevalent aspirin intake is. We’re currently looking into alternative study designs and have promising ideas as to how to proceed,” she added.
In the study they report, aspirin was being taken for a variety of comorbidities. The most common were cardiovascular disease and hypercholesterolemia, followed by age (men over 45 and women over 55 are recommended to take aspirin as prophylaxis against myocardial infarction and stroke, respectively, the authors note). It was taken either as 81 mg daily (baby aspirin) or as 325 mg daily (regular strength).
Aspirin is easy to take, has a generally favorable adverse-effect profile, and reduces the risk for many different cancer types, as well as cardiovascular disease, the researchers comment. However, long-term use can lead to gastrointestinal bleeding and peptic ulcers, so the benefit from long-term use must be weighed against potential harm. It is not clear, at the moment, whether long-term aspirin ingestion would be needed to inhibit sVS growth, or whether it could be used intermittently to minimize its toxicity, they write.
No Approved Therapies
“Patients typically come to see us with hearing loss and tinnitus or ringing in the ears. If a hearing test shows asymmetry between the 2 ears, we typically obtain a contrast-enhanced MRI of the brain to look for these tumors,” Dr. Stankovic told Medscape Medical News.
“Management depends on age, tumor size at diagnosis, growth rate, and the patient’s overall health. Generally speaking, we tend to follow these tumors with serial MRI scans, reserving intervention for growing tumors,” she said. Intervention involves surgery (via craniotomy) or radiation, both of which are associated with serious complications, she noted.
“Currently, there are no FDA-approved drug therapies to treat these tumors,” she added.
Results Suggest Inhibition of Growth
For their review, the researchers analyzed the records of 689 patients with sVS, of whom 347 (50.3%) were followed by MRI scans.
Among the 347 patients who were followed by serial MRI scans, growth of the sVS was demonstrated in 187 patients, of whom 33 patients (18%) were regular users of aspirin, and no growth was demonstrated in 160 patients, of whom 48 patients (30%) were regular users of aspirin.
The difference in sVS growth vs no growth between aspirin users and nonusers was statistically significant (P = .0076), with an odds ratio (OR) of 0.50, and was not confounded by age or sex, the researchers report.
The researchers also conducted an age-adjusted analysis, because the age of the aspirin users (median, 68 years) was significantly different from the nonusers (median, 63 years), and also because sVS can be significantly inversely correlated with age.
This age-adjusted analysis also found a significant difference in SVS growth vs no growth between aspirin users and age-matched nonusers ( P = .0061; OR, 0.47).
However, another analysis, which analyzed the sVS growth rate “numerically as opposed to categorically” did not reach statistical significance, although it showed a trend toward less growth in aspirin users. This numerical analysis measured the amount of growth, Dr. Stankovic explained, whereas the other categorical analysis was a “yes or no” answer. In the categorical analysis, any tumor that showed any growth (i.e., 1 mm or 4 mm) would be in the “yes” category, she said.
The work was funded by grants from the National Institute on Deafness and Other Communications Disorders and by the Bertarelli Foundation. The authors have disclosed no relevant financial relationships.
Otol Neurotol. 2014:35: 353-357. Abstract