Adult Rhabdomyosarcoma: A Retrospective Analysis of 40 Patients Treated at a Single Institution

Abstract

Purpose/Objective(s): Rhabdomyosarcoma (RMS) is a soft tissue malignancy thought to originate from immature striated skeletal muscle cells. Nonetheless, RMS can arise in sites where skeletal muscle is not normally found. RMS is rare in adults, accounting for 2%-5% of adult soft tissue sarcomas, and most often arises in the head and neck region. Experience with treatment of adults with RMS is limited, but data suggest that adults have inferior outcomes compared with children. The purpose of this retrospective study is to review the clinical outcomes of adult patients diagnosed with primary RMS. Materials/Methods: The clinicopathologic features, treatment methods, and disease outcomes were reviewed retrospectively for 40 adults (patients ages 18 years or older) with RMS treated between 2003 and 2015 at a single institution. Overall survival (OS) and recurrence-free survival (RFS) were estimated using the Kaplan-Meier method. Results: Mean age was 45 years (range: 19-81), median follow-up time was 16.2 months, (range: 0.8-140 months), and 23 patients (57.5%) were female. Patients presented with localized (24, 60.0%), regional (4, 10.0%), distant (11, 27.5%), and undetermined (1, 2.5%) extents of disease. Tumor sites included head and neck (15, 37.5%), upper extremity/shoulder (2, 5.0%), lower extremity (6, 15.0%), thorax (1, 2.5%), trunk (2, 5.0%), spine/sacrum/bony pelvis (bone; 1, 2.5%), abdomen/pelvis/peritoneum/gastrointestinal tract (soft tissue; 7, 17.5%), retroperitoneum (2, 5.0%), gynecologic (3, 7.5%), and illdefined/not specified (1, 2.5%). RMS histology groups were alveolar (13, 32.5%), pleomorphic (9, 22.5%), embryonal (7, 17.5%), and not otherwise specified (11, 27.5%). Patients were treated according to the following treatment categories: no surgery and no radiation (RT; 3, 7.5%), surgical treatment, no RT (7, 17.5%), no surgery, RT alone (17, 42.5%), preoperative RT -> surgery (6, 15.0%), preoperative RT -> surgery ->postoperative RT (1, 2.5%), or surgery -> postoperative RT (6, 15.0%) The majority of patients received chemotherapy on presentation (33, 82.5%); vincristine, adriamycin, cyclophosphamide alternating with ifosfamide, and etoposide (VAC/IE) was the most common regimen. Five-year OS and RFS were 34.4% (95% CI: 18.1-51.3) and 31.8% (95% CI: 14.8-50.4), respectively (Table 1). Conclusion: Adult RMS is an aggressive tumor with a significant incidence of metastatic recurrence; however, there are long-term survivors. Further study is necessary to determine whether adult patients who adhere to guidelines for treatment of pediatric RMS have superior outcomes. (Table presented).