Clinical Behavior of Acoustic Tumors: A Flow Cytometric Analysis

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Abstract
• Objective. —Recently, nonsurgical treatment of acoustic tumors has been advocated as an alternative to surgical resection. Because of the relatively short follow-up in reported series of radiation-treated acoustic tumors, the lack of growth of some tumors may merely reflect the variable biologic growth potential of these tumors and not the result of treatment. DNA flow cytometry has been used to predict biologic activity in other solid tumors. It is applied in this study to assess the variability of growth potential in a typical acoustic tumor population and to determine whether relationships exist between flow cytometric data and clinical characteristics of acoustic tumors. Design. —DNA flow cytometry techniques were used to evaluate formalin—fixed, paraffin-embedded tissue previously obtained from patients who were surgically treated for acoustic neuromas. Relationships between flow cytometry data and historical data were also statistically evaluated. Setting. —Tissue samples were from patients of a large private otologic practice. Patients. —Subjects were a convenience sample of 49 patients (26 female and 23 male) with a mean age of 59 years who had undergone surgical removal of an acoustic neuroma. None of the patients had other stigmata of neurofibromatosis or tumor recurrence. All tissue specimens were pathologically confirmed acoustic neuromas, with a range in tumor size from 1 to 6 cm. Main Outcome Measures. —The measures included DNA ploidy and S-phase fraction. Historical data included age, sex, size of tumor, presenting symptom, and symptom duration. Results. —All 49 tumors showed a diploid distribution, with S-phase values ranging from 1.07% to 20.74% (mean±SD, 6.30±4.24). The ploidy and S-phase data compare favorably with previously published data in which fresh tissue was used. There were no statistically significant relationships between S-phase value and historical data. Conclusions. —The wide range of S-phase values is consistent with a large variation in tumor growth potential and suggests caution in interpreting the results of radiation treatment of acoustic tumors when follow-up is relatively short. (Arch Otolaryngol Head Neck Surg. 1993;119:269-271)