Outcomes for patients with perineal and perianal rhabdomyosarcoma: A report from the Children's Oncology Group Soft Tissue Sarcoma Committee.

Purpose: To describe clinical features, risk factors, and outcomes of patients with perineal and perianal rhabdomyosarcoma.

Methods: The records of 51 patients (38 perineal and 13 perianal) enrolled on Children's Oncology Group clinical trials between 1997 and 2012 were reviewed.

Results: At presentation, 53% were female, 65% were older than 10 years of age, 76% were alveolar histology, 76% were more than 5 cm, 84% were invasive, 65% were regional node positive by imaging, 49% were metastatic, only 16% were grossly resected upfront, and 25% of patients had a delayed excision. At a median follow-up of 6.13 years, estimated 5-year event-free survival (EFS) was 38% [22.17%-53.38%], and overall survival (OS) was 42% [26.66%-58.21%]. The rates of local, regional, and distant failure were 15.6%, 13.7%, 43.1%, respectively; all failures ultimately died. By univariate analysis, only age more than 10 years negatively impacted 5-year EFS (p = .023) and OS (p = .09), and IRS Group also impacted OS (p = .043). In Cox proportional hazards model, neither of these variables were significant after adjusting for other factors.

Conclusion: Patients with perineal and perianal rhabdomyosarcoma have a poor overall prognosis, probably related to poor patient and disease characteristics at presentation.