Abstract

SERRA KAMER¹, Meltem Öztürk¹, Eda Ataseven², Beril BALCI¹, Bengu KADIOGLU³, Mehmet KANTAR², Deniz KIZMAZOGLU⁴, Yavuz ANACAK¹

¹Ege University, Radiation Oncology, IZMIR, Turkey; ²Ege University, Pediatric Oncology, IZMIR, Turkey; ³Behcet Uz Childrens Hospital, Pediatric Oncology, IZMIR, Turkey; ⁴Tepecik Childrens Research Hospital, Pediatric Oncology, IZMIR, Turkey

Management of pediatric rhabdomyosarcoma (RMS) involves the use of surgery, radiotherapy and chemotherapy in an orchestrated manner.  Treatment data obtained from the large, well-organized, multicentric series of the pediatric oncology groups does not necessarily fits in the data of a single center.  In IRS studies of North America patients are classified into risk groupings to deliver optimum treatment. The aim of the present study was to evaluate the survival of pediatric RMS patients and to check the validity of IRS risk classification for the data of the Ege University Hospital.

72 patients who underwent radiotherapy between 2001-2018 were analyzed retrospectively. 29 of them were girls and 43 were boys; girl/boy ratio was 0.67; their median age was 5 (1-18). Common sites were H&N 31 cases (43.1%) – orbita 8, parameningeal 16, non-parameningeal 7; GU 20 cases (27.8%) - bladder 12 cases, other GU 8; extremities 6 (8.3%) cases and other sites 15 cases (20.8%). The most frequent histologic subtype was embryonal 45 cases (62.5%), followed by alveolar 11 (15.3%), myxoid 9 (12.5%), undifferentiated 4 (5.6%), and spindle cell 3 (4.2%). At the time of diagnosis there were lymph node metastates in 13 (18.1%) and distant metastases in 15 (20.8%); lungs were the most common site (11 cases). According to IRS risk classification 13 patients were in low-risk group (LRG), 42 in were intermediate-risk group (IRG) and 16 were high-risk group (HRG). Tumor resection was performed in 50 (69.4%), all patients received radiotherapy and chemotherapy. Radiotherapy delivered as external irradiation (ERT) in 51 (70.8%) cases, brachytherapy (BRT) in 16 (22.2%) and ERT+BRT in 5 (6.9%). ERT doses were 36 – 54 Gy with 1.8 Gy daily fractions. BRT delivered in in 6-8 twice-daily fractions in 3-4 days with 2.5-3 Gy fraction doses. 

After a median follow-up of 44.5 months (2-220), tumor recurrence occurred in 20 patients (27.8%). Median time to recurrence was 31 months. Of those recurrences 7 (9.7%) were local, 4 (5.6%) were in regional nodes and 9 (12.5%) were distant – 5 in lungs. 5-y OS was 68.0% in the whole group, and it was 90.0% in LRG, 75.8% in IRG, and 28.6% in HRG (p<0.01). 5-y DFS was 68.2% in the whole group, and it was 90.9% in LRG, 69.1% in IRG, and 37.9% in HRG (p<0.05)

Radiotherapy is an important component of the RMS treatment. In our series of 72 patients treated with radiotherapy, relapse rates and survival was not different from the previous reports. IRS risk classification perfectly estimates the prognosis of the patients and our data strongly supports the use of IRS risk grouping in the management of pediatric rhabdomyosarcoma.