Clinicopathologic analysis of patients with adult rhabdomyosarcoma

BACKGROUND. Rhabdomyosarcoma (RMS) in adults (age ≥ 16 years) is rare, accounting for less than 3% of adult soft tissue sarcomas. There is little information describing the disease biology or clinicopathologic factors that influence survival in adults with RMS. The objective of this study was to define the factors in patients with adult RMS that predict outcome, disease progression, and survival. METHODS. Eighty-four adult patients with a pathologic diagnosis of RMS that was confirmed by immunohistochemistry were identified by a prospective inpatient data base during the period 1982-1999 and were analyzed for disease specific survival and metastasis free survival using the Kaplan-Meier actuarial method. Statistical significance was evaluated using the log-rank test for univariate influence and a Cox regression model for multivariate influence. RESULTS. The median disease specific survival was 22 months. Patient age, extent of disease, tumor size at the time of diagnosis, and margin status after resection were significant predictors of disease specific survival. Patients who underwent a complete resection had a significantly longer median survival (105 months) compared with any other subgroup of patients. The histologic subtype did not predict patient survival but did vary with patient age. Most notably, the proportion of the pleomorphic subtype increased with advancing age, accounting for 42% of RMS in patients over the age of 40 years. CONCLUSIONS. The most important predictors of outcome in patients with adult RMS are patient age, tumor size, extent of disease, and margin status after resection. In contrast to patients with pediatric RMS, no association was noted between survival and histologic subtype in this group of patients with adult RMS. All histologic subtypes of RMS are aggressive malignancies with poor disease specific survival despite aggressive multimodality management.