Aspirin Shows No Association with Vestibular Schwannoma Growth

Comment: Several studies over the past 10 years have suggested that daily aspirin use can prevent tumor growth in some types of cancer, most notably colorectal. These studies likely prompted several groups to investigate the use of aspirin in controlling the growth of vestibular schwannomas. Between 2014 and 2017 at least four studies addressed this issue, and at least one of these shows a salutary effect. This form of therapy is very appealing due to its relatively low risk, common use, and ease of availability. The study by MacKeith and colleagues uses a case-control design, and, in a total of 437 patients did not show the ability to stem the growth of these neoplasms. —Samuel H. Selesnick, MD

Is aspirin intake is associated with reduced growth of vestibular schwannomas (VS)?

Bottom Line:
After controlling for covariates, findings did not demonstrate an association between tumor size and aspirin intake. Only tumor size at diagnosis appears to be predictive of VS growth risk.

Background: Active treatment, including microsurgery or radiotherapy/radiosurgery (both of which carry significant potential morbidity), is usually reserved for patients with larger tumors at diagnosis or those that demonstrate growth over a period of observation. Currently, there are no systemic therapies available for the treatment of sporadic VS, although bevacizumab is used within the setting of neurofibromatosis type 2 (NF2). An increasing volume of research has suggested that aspirin has antineoplastic effects in several solid tumor types, most clearly demonstrated in colorectal neoplasia.

Study design: Retrospective, observational case-control study (220 cases [patients with VS proven to have grown] and 217 controls [patients with stable VS]) through postal questionnaires and telephone interviews.

Setting: Departments of Otolaryngology, Neurosurgery, and Clinical Oncology, Addenbrooke’s Hospital, Cambridge, United Kingdom.

Synopsis: Of the 437 participants in the study, 223 were male and 86 had exposure to regular aspirin. The dose reported was 75 mg daily for almost all patients, with only four stating a higher dose of 150 or 300 mg. Combining cases and controls, the mean tumor size was 11.2 mm, but the mean tumor size of controls was significantly less than cases. Neither age, sex, nor aspirin intake were associated with tumor growth, but larger initial tumor size at diagnosis was strongly associated with tumor growth. Using propensity score matching to match patients by age, sex, and tumor size demonstrated that aspirin intake was not associated with tumor growth/stability. Only 8% of respondents stated that they were unable to take aspirin. The most common reasons given for this were gastric intolerance/dyspepsia, asthma, peptic ulcer disease, warfarin use, bleeding risk (e.g., epistaxis), and allergy. No patient reported having renal failure, and only one reported liver failure. Limitations included the retrospective study design, which is prone to bias.

Citation: MacKeith S, Wasson J, Baker C, et al. Aspirin does not prevent growth of vestibular schwannomas: a case-controlled study? Laryngoscope. 2018;128:2139–2144.