Background Local control remains a challenge in pediatric parameningeal rhabdomyosarcoma (PM-RMS), and survival after local failure (LF) is poor. Identifying patients with a high risk of LF is of great interest to clinicians. In this study, we examined whether tumor response to induction chemotherapy (CT) could predict LF in embryonal PM-RMS. Methods We identified 24 patients with embryonal PM-RMS, age 2 to 18 years, with complete magnetic resonance imaging and gross residual disease after surgical resection. All patients received proton radiation therapy (RT), median dose 50.4 GyRBE (50.4-55.8 GyRBE). Tumor size was measured before initial CT and before RT. Results With a median follow-up time of 4.1 years for survivors, LF was seen in 9 patients (37.5%). The median time from the initiation of CT to the start of RT was 4.8 weeks. Patients with LF had a similar initial (pre-CT) tumor volume compared with patients with local controlled (LC) (54 cm3 vs 43 cm3, P=.9) but a greater median volume before RT (pre-RT) (40 cm3 vs 7 cm3, P=.009) and a smaller median relative percent volume reduction (RPVR) in tumor size (0.4% vs 78%, P<.001). Older age (P=.05), larger pre-RT tumor volume (P=.03), and smaller RPVR (P=.003) were significantly associated with actuarial LF on univariate Cox analysis. Conclusions Poor response to induction CT appears to be associated with an increased risk of LF in pediatric embryonal PM-RMS.
|Original language||English (US)|
|Number of pages||10|
|Journal||International Journal of Radiation Oncology Biology Physics|
|State||Published - Jun 1 2015|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cancer Research